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From the Archives of the AFIP

Imaging of Synovial Chondromatosis with Radiologic-Pathologic Correlation¹

¹ From the Departments of Radiologic Pathology (M.D.M., J.A.V.) and Soft Tissue Pathology (J.C.F.-S.), Armed Forces Institute of Pathology, 6825 16th St NW, Building 54, Room M-133A, Washington, DC 20306; Department of Radiology and Nuclear Medicine, Uniformed Services University of the Health Sciences, Bethesda, Md (M.D.M.); and Department of Orthopedic Surgery, Walter Reed Army Medical Center, Washington, DC (D.A.G.). Received May 16, 2007; revision requested June 5 and received June 21; accepted June 22. All authors have no financial relationships to disclose. Address correspondence to M.D.M. (e-mail: murphey{at}afip.osd.mil).

	Abstract

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Clinical Characteristics Pathologic Features Imaging Features Treatment and Prognosis Malignant Transformation of... Summary References

 
Primary synovial chondromatosis represents an uncommon benign neoplastic process with hyaline cartilage nodules in the subsynovial tissue of a joint, tendon sheath, or bursa. The nodules may enlarge and detach from the synovium. The knee, followed by the hip, in male adults are the most commonly involved sites and patient population. The pathologic appearance may simulate chondrosarcoma because of significant histologic atypia, and radiologic correlation to localize the process as synovially based is vital for correct diagnosis. Radiologic findings are frequently pathognomonic. Radiographs reveal multiple intraarticular calcifications (70%–95% of cases) of similar size and shape, distributed throughout the joint, with typical "ring-and-arc" chondroid mineralization. Extrinsic erosion of bone is seen in 20%–50% of cases. Computed tomography (CT) optimally depicts the calcified intraarticular fragments and extrinsic bone erosion. Magnetic resonance (MR) imaging findings are more variable, depending on the degree of mineralization, although the most common pattern (77% of cases) reveals low to intermediate signal intensity with T1-weighting and very high signal intensity with T2-weighting with hypointense calcifications. These signal intensity characteristics on MR images and low attenuation of the nonmineralized regions on CT scans reflect the high water content of the cartilaginous lesions. CT and MR imaging depict the extent of the synovial disease (particularly surrounding soft-tissue involvement) and lobular growth. Secondary synovial chondromatosis can be distinguished from primary disease both radiologically (underlying articular disease and fewer chondral bodies of variable size and shape) and pathologically (concentric rings of growth). Treatment of primary disease is surgical synovectomy with removal of chondral fragments; recurrence rates range from 3% to 23%. Malignant transformation to chondrosarcoma is unusual (5% of cases) and, although difficult to distinguish from benign disease, is suggested by multiple recurrences and marrow invasion. Recognizing the appearances of primary synovial chondromatosis, which reflect their underlying pathologic characteristics, improves radiologic assessment and is important to optimize patient management.

	LEARNING OBJECTIVES FOR TEST 6

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Clinical Characteristics Pathologic Features Imaging Features Treatment and Prognosis Malignant Transformation of... Summary References

 
After reading this article and taking the test, the reader will be able to:

• Identify the radiologic manifestations of synovial chondromatosis.
  
• Describe the pathologic basis of the radiologic features of synovial chondromatosis.
  
• Discuss the pathologic spectrum of synovial chondromatosis, as well as the treatment options and prognosis.
  

	Introduction

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Clinical Characteristics Pathologic Features Imaging Features Treatment and Prognosis Malignant Transformation of... Summary References

 
Synovial chondromatosis was first described by Leannac in 1813 (1–3). However, its current description was not applied until 1958 by Jaffe (4). Previous terminology for this lesion includes synovial osteochondromatosis, synovial chondrometaplasia, articular ecchondrosis, and synovial chondrosis (1–9). Synovial chondromatosis has been divided into primary and secondary forms. Primary synovial chondromatosis, the focus of this article, was originally considered to represent chondroid metaplasia in the synovium of a joint with resultant formation of multiple intraarticular chondral bodies. However, current cytogenetic evaluation demonstrates that primary synovial chondromatosis is a benign neoplastic process. An identical process can also involve the synovium that extends along tendons and bursae and is frequently referred to as tenosynovial or bursal chondromatosis, respectively. Secondary synovial chondromatosis is associated with joint abnormalities, such as mechanical or arthritic conditions, that cause intraarticular chondral bodies (10). Primary synovial chondromatosis typically affects adults, predominantly men, in the third to fifth decades of life (1,2,6–9). The knee is the most commonly affected site (1,7–9).

Synovial chondromatosis is a benign, typically self-limited process that may recur locally. However, its histologic appearance may suggest a more aggressive chondroid neoplasm (chondrosarcoma) to the less experienced pathologist. True malignant transformation of synovial chondromatosis to chondrosarcoma is an unusual complication of this disease (11,12). Imaging features of synovial chondromatosis are frequently pathognomonic. Radiographic features include multiple intraarticular chondral bodies with "ring-and-arc" chondroid mineralization and extrinsic erosion of bone on both sides of the joint (2,7,9,13). Computed tomography (CT) is the optimal radiologic modality to identify and characterize these calcified intraarticular fragments and extrinsic erosion of bone (2,7,14). The magnetic resonance (MR) imaging appearance of synovial chondromatosis is variable owing to the extent of mineralization and ossification of the chondral bodies, although the extent of involvement is exquisitely depicted (1,2,5,7,15,16). The noncalcified regions of hyaline cartilage neoplasia typically demonstrate high signal intensity on T2-weighted MR images because of the high water content of this tissue. In this article, the clinical features, pathologic characteristics, spectrum of radiologic appearances, and complications and prognosis of synovial chondromatosis with emphasis on primary disease are discussed and illustrated.

	Clinical Characteristics

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Clinical Characteristics Pathologic Features Imaging Features Treatment and Prognosis Malignant Transformation of... Summary References

 
Primary synovial chondromatosis is a relatively uncommon disease that typically affects patients in the third to fifth decades of life, although the age range for clinical presentation is wide (2,7, 8,17). Men are affected two to four times more frequently than women (2,7,8,17). There are only rare reports of familial association (2% of cases) that in some cases may be related to type 2 collagen abnormalities, such as have been described for Wagner-Stickler syndrome (hereditary arthro-ophthalmopathy) (2,7,8,17,18).

Clinical symptoms typically include pain (85%–100% of cases), swelling (42%–58%), and restriction of range of motion (38%–55%) of the affected joint (19–22). Physical examination of patients with synovial chondromatosis reveals diffuse joint swelling and enlargement (42%–58% of cases), articular tenderness (20%–41%), articular crepitus (20%–33%), locking (5%–12%), and palpable nodules or a mass (3%–20%) (19–21). Associated muscle atrophy has been reported in up to 21% of cases in a Canadian series of 18 patients but in only 3% of 32 patients in another study (19,21,23). Symptoms are often insidious at disease onset and are gradually progressive, although rare spontaneous regression has been reported (22). The duration of clinical symptoms before diagnosis is often long, with an average of 5 years (18–21).

Synovial chondromatosis commonly occurs within joints. The knee is the most frequently affected articulation, with more than 50%–65% of cases occurring in that location (2,7–9) (Figs 1, 2). Other commonly involved joints are the hip, elbow, shoulder, and ankle. In our experience, the hip is the second most frequently affected joint (7–9,13) (Figs 3, 4). Less commonly involved joints include the metacarpophalangeal, inter-phalangeal, distal radioulnar, acromioclavicular, temporomandibular (Fig 5), proximal tibiofibular, and apophyseal articulations (24–32). Primary synovial chondromatosis has been reported to affect more than one joint, particularly both knees, in 5%–10% of cases (1,5). However, in our experience and in larger series, primary synovial chondromatosis is almost invariably a monoarticular disease, with only rare cases of true polyarticular involvement (18–20). We believe that many cases reported as polyarticular primary synovial chondromatosis actually represent secondary synovial chondromatosis (18). Polyarticular involvement may be more frequent in familial cases and in patients with associated syndromes (21).

View larger version (122K): [in this window] [in a new window] [Download PPT slide]   Figure 1a.  Primary synovial chondromatosis of the knee in a 73-year-old man with progressive swelling. (a, b) Oblique (a) and lateral (b) knee radiographs show only subtle abnormality of a joint effusion (*), extrinsic erosion of the anterolateral tibia (large arrowheads), and several possible minute calcifications posteriorly (small arrowheads in b). (c, d) Two axial CT images reveal a large, lobulated, low-attenuation mass about the knee (*) with several subtle calcifications (small arrows) and extrinsic erosion of the anterolateral tibia (large arrow in c). (e, f) Photographs of intraoperative open arthrotomy and débridement demonstrate multiple cartilaginous nodules (* in e) about the femur (Fe) and subsequent resection of a component containing synovium (tissue within oval in f) and embedded cartilaginous fragments (arrows in f).

View larger version (154K): [in this window] [in a new window] [Download PPT slide]   Figure 1b.  Primary synovial chondromatosis of the knee in a 73-year-old man with progressive swelling. (a, b) Oblique (a) and lateral (b) knee radiographs show only subtle abnormality of a joint effusion (*), extrinsic erosion of the anterolateral tibia (large arrowheads), and several possible minute calcifications posteriorly (small arrowheads in b). (c, d) Two axial CT images reveal a large, lobulated, low-attenuation mass about the knee (*) with several subtle calcifications (small arrows) and extrinsic erosion of the anterolateral tibia (large arrow in c). (e, f) Photographs of intraoperative open arthrotomy and débridement demonstrate multiple cartilaginous nodules (* in e) about the femur (Fe) and subsequent resection of a component containing synovium (tissue within oval in f) and embedded cartilaginous fragments (arrows in f).

View larger version (119K): [in this window] [in a new window] [Download PPT slide]   Figure 1c.  Primary synovial chondromatosis of the knee in a 73-year-old man with progressive swelling. (a, b) Oblique (a) and lateral (b) knee radiographs show only subtle abnormality of a joint effusion (*), extrinsic erosion of the anterolateral tibia (large arrowheads), and several possible minute calcifications posteriorly (small arrowheads in b). (c, d) Two axial CT images reveal a large, lobulated, low-attenuation mass about the knee (*) with several subtle calcifications (small arrows) and extrinsic erosion of the anterolateral tibia (large arrow in c). (e, f) Photographs of intraoperative open arthrotomy and débridement demonstrate multiple cartilaginous nodules (* in e) about the femur (Fe) and subsequent resection of a component containing synovium (tissue within oval in f) and embedded cartilaginous fragments (arrows in f).

View larger version (129K): [in this window] [in a new window] [Download PPT slide]   Figure 1d.  Primary synovial chondromatosis of the knee in a 73-year-old man with progressive swelling. (a, b) Oblique (a) and lateral (b) knee radiographs show only subtle abnormality of a joint effusion (*), extrinsic erosion of the anterolateral tibia (large arrowheads), and several possible minute calcifications posteriorly (small arrowheads in b). (c, d) Two axial CT images reveal a large, lobulated, low-attenuation mass about the knee (*) with several subtle calcifications (small arrows) and extrinsic erosion of the anterolateral tibia (large arrow in c). (e, f) Photographs of intraoperative open arthrotomy and débridement demonstrate multiple cartilaginous nodules (* in e) about the femur (Fe) and subsequent resection of a component containing synovium (tissue within oval in f) and embedded cartilaginous fragments (arrows in f).

View larger version (129K): [in this window] [in a new window] [Download PPT slide]   Figure 1e.  Primary synovial chondromatosis of the knee in a 73-year-old man with progressive swelling. (a, b) Oblique (a) and lateral (b) knee radiographs show only subtle abnormality of a joint effusion (*), extrinsic erosion of the anterolateral tibia (large arrowheads), and several possible minute calcifications posteriorly (small arrowheads in b). (c, d) Two axial CT images reveal a large, lobulated, low-attenuation mass about the knee (*) with several subtle calcifications (small arrows) and extrinsic erosion of the anterolateral tibia (large arrow in c). (e, f) Photographs of intraoperative open arthrotomy and débridement demonstrate multiple cartilaginous nodules (* in e) about the femur (Fe) and subsequent resection of a component containing synovium (tissue within oval in f) and embedded cartilaginous fragments (arrows in f).

View larger version (122K): [in this window] [in a new window] [Download PPT slide]   Figure 1f.  Primary synovial chondromatosis of the knee in a 73-year-old man with progressive swelling. (a, b) Oblique (a) and lateral (b) knee radiographs show only subtle abnormality of a joint effusion (*), extrinsic erosion of the anterolateral tibia (large arrowheads), and several possible minute calcifications posteriorly (small arrowheads in b). (c, d) Two axial CT images reveal a large, lobulated, low-attenuation mass about the knee (*) with several subtle calcifications (small arrows) and extrinsic erosion of the anterolateral tibia (large arrow in c). (e, f) Photographs of intraoperative open arthrotomy and débridement demonstrate multiple cartilaginous nodules (* in e) about the femur (Fe) and subsequent resection of a component containing synovium (tissue within oval in f) and embedded cartilaginous fragments (arrows in f).

View larger version (128K): [in this window] [in a new window] [Download PPT slide]   Figure 2a.  Primary synovial chondromatosis of the knee in a 23-year-old man with pain, swelling, and locking. (a) Lateral knee radiograph shows extensive areas of intraarticular calcification about the knee with typical ring-and-arc appearance of chondroid tissue in the majority of foci and a target appearance in one posterosuperiorly (arrow). Joint effusion is seen anteriorly (*). (b, c) Sagittal proton-density–weighted (b, 200/13 [repetition time msec/echo time msec]) and T2-weighted fat-suppressed (c, 5150/73) MR images reveal the extensive diffuse synovial process (*) with high signal intensity on the long repetition time (TR) image and innumerable osteochondral bodies (*). Several of these intraarticular fragments (arrows in b and c) have higher signal intensity on the proton-density image (arrows in b), findings consistent with maturation to contain elements of yellow marrow. There is subtle extrinsic erosion of the anterior tibia (arrowheads). (d) Photograph of a sagittally sectioned, whole-mounted specimen (hematoxylin-eosin [H-E] stain) from a different patient’s knee demonstrates similar features with extensive multilobular chondroid metaplasia (*), extrinsic erosion of bone (arrowheads), and extension into a popliteal cyst (P) with a bursal synovial lining (between arrows).

View larger version (178K): [in this window] [in a new window] [Download PPT slide]   Figure 2b.  Primary synovial chondromatosis of the knee in a 23-year-old man with pain, swelling, and locking. (a) Lateral knee radiograph shows extensive areas of intraarticular calcification about the knee with typical ring-and-arc appearance of chondroid tissue in the majority of foci and a target appearance in one posterosuperiorly (arrow). Joint effusion is seen anteriorly (*). (b, c) Sagittal proton-density–weighted (b, 200/13 [repetition time msec/echo time msec]) and T2-weighted fat-suppressed (c, 5150/73) MR images reveal the extensive diffuse synovial process (*) with high signal intensity on the long repetition time (TR) image and innumerable osteochondral bodies (*). Several of these intraarticular fragments (arrows in b and c) have higher signal intensity on the proton-density image (arrows in b), findings consistent with maturation to contain elements of yellow marrow. There is subtle extrinsic erosion of the anterior tibia (arrowheads). (d) Photograph of a sagittally sectioned, whole-mounted specimen (hematoxylin-eosin [H-E] stain) from a different patient’s knee demonstrates similar features with extensive multilobular chondroid metaplasia (*), extrinsic erosion of bone (arrowheads), and extension into a popliteal cyst (P) with a bursal synovial lining (between arrows).

View larger version (194K): [in this window] [in a new window] [Download PPT slide]   Figure 2c.  Primary synovial chondromatosis of the knee in a 23-year-old man with pain, swelling, and locking. (a) Lateral knee radiograph shows extensive areas of intraarticular calcification about the knee with typical ring-and-arc appearance of chondroid tissue in the majority of foci and a target appearance in one posterosuperiorly (arrow). Joint effusion is seen anteriorly (*). (b, c) Sagittal proton-density–weighted (b, 200/13 [repetition time msec/echo time msec]) and T2-weighted fat-suppressed (c, 5150/73) MR images reveal the extensive diffuse synovial process (*) with high signal intensity on the long repetition time (TR) image and innumerable osteochondral bodies (*). Several of these intraarticular fragments (arrows in b and c) have higher signal intensity on the proton-density image (arrows in b), findings consistent with maturation to contain elements of yellow marrow. There is subtle extrinsic erosion of the anterior tibia (arrowheads). (d) Photograph of a sagittally sectioned, whole-mounted specimen (hematoxylin-eosin [H-E] stain) from a different patient’s knee demonstrates similar features with extensive multilobular chondroid metaplasia (*), extrinsic erosion of bone (arrowheads), and extension into a popliteal cyst (P) with a bursal synovial lining (between arrows).

View larger version (147K): [in this window] [in a new window] [Download PPT slide]   Figure 2d.  Primary synovial chondromatosis of the knee in a 23-year-old man with pain, swelling, and locking. (a) Lateral knee radiograph shows extensive areas of intraarticular calcification about the knee with typical ring-and-arc appearance of chondroid tissue in the majority of foci and a target appearance in one posterosuperiorly (arrow). Joint effusion is seen anteriorly (*). (b, c) Sagittal proton-density–weighted (b, 200/13 [repetition time msec/echo time msec]) and T2-weighted fat-suppressed (c, 5150/73) MR images reveal the extensive diffuse synovial process (*) with high signal intensity on the long repetition time (TR) image and innumerable osteochondral bodies (*). Several of these intraarticular fragments (arrows in b and c) have higher signal intensity on the proton-density image (arrows in b), findings consistent with maturation to contain elements of yellow marrow. There is subtle extrinsic erosion of the anterior tibia (arrowheads). (d) Photograph of a sagittally sectioned, whole-mounted specimen (hematoxylin-eosin [H-E] stain) from a different patient’s knee demonstrates similar features with extensive multilobular chondroid metaplasia (*), extrinsic erosion of bone (arrowheads), and extension into a popliteal cyst (P) with a bursal synovial lining (between arrows).

View larger version (54K): [in this window] [in a new window] [Download PPT slide]   Figure 3a.  Primary synovial chondromatosis of the hip in a 73-year-old woman with hip pain for 20 years. (a) Anteroposterior radiograph of the hip shows extensive erosion of the right femoral neck (arrows) and slight widening of the hip joint but no apparent calcifications. (b) Arthogram reveals multiple circular filling defects resulting from the intraarticular chondral fragments. (c) Bone scan shows prominent but nonspecific increased radionuclide uptake about the right hip. (d) Photograph of the gross specimen demonstrates multiple chondral bodies (arrowheads) and extensive erosion of the femoral neck (arrows).

View larger version (35K): [in this window] [in a new window] [Download PPT slide]   Figure 3b.  Primary synovial chondromatosis of the hip in a 73-year-old woman with hip pain for 20 years. (a) Anteroposterior radiograph of the hip shows extensive erosion of the right femoral neck (arrows) and slight widening of the hip joint but no apparent calcifications. (b) Arthogram reveals multiple circular filling defects resulting from the intraarticular chondral fragments. (c) Bone scan shows prominent but nonspecific increased radionuclide uptake about the right hip. (d) Photograph of the gross specimen demonstrates multiple chondral bodies (arrowheads) and extensive erosion of the femoral neck (arrows).

View larger version (129K): [in this window] [in a new window] [Download PPT slide]   Figure 3c.  Primary synovial chondromatosis of the hip in a 73-year-old woman with hip pain for 20 years. (a) Anteroposterior radiograph of the hip shows extensive erosion of the right femoral neck (arrows) and slight widening of the hip joint but no apparent calcifications. (b) Arthogram reveals multiple circular filling defects resulting from the intraarticular chondral fragments. (c) Bone scan shows prominent but nonspecific increased radionuclide uptake about the right hip. (d) Photograph of the gross specimen demonstrates multiple chondral bodies (arrowheads) and extensive erosion of the femoral neck (arrows).

View larger version (127K): [in this window] [in a new window] [Download PPT slide]   Figure 3d.  Primary synovial chondromatosis of the hip in a 73-year-old woman with hip pain for 20 years. (a) Anteroposterior radiograph of the hip shows extensive erosion of the right femoral neck (arrows) and slight widening of the hip joint but no apparent calcifications. (b) Arthogram reveals multiple circular filling defects resulting from the intraarticular chondral fragments. (c) Bone scan shows prominent but nonspecific increased radionuclide uptake about the right hip. (d) Photograph of the gross specimen demonstrates multiple chondral bodies (arrowheads) and extensive erosion of the femoral neck (arrows).

View larger version (146K): [in this window] [in a new window] [Download PPT slide]   Figure 4a.  Primary synovial chondromatosis of the hip with bursal extension in a 27-year-old man with chronic hip pain. (a) Anteroposterior hip radiograph shows a widening right hip joint with subtle acetabular erosion (arrow) and calcifications (arrowheads) most apparent overlying the obturator canal. (b) Axial CT scan reveals a low-attenuation intraarticular mass about the femoral neck (*), extrinsic erosion of bone (solid arrow), and medial extension containing calcification that represents involvement of the obturator externus bursa (open arrow). (c–e) Axial contrast-enhanced T1-weighted with fat suppression (c, 600/20), axial T2-weighted (d, 2500/80), and coronal T1-weighted (e, 800/10) MR images demonstrate the synovial process diffusely involving the joint; low signal intensity is seen with T1-weighting and high signal intensity with T2-weighting (*). Bursal extensions medially and posteriorly are also seen, particularly on the contrast-enhanced image with peripheral and septal enhancement (arrowheads). Lower-signal-intensity regions within the high-signal-intensity abnormality on long TR images and small areas of rimlike enhancement represent osteochondral fragments (arrows in c and d). (f) CT scan obtained at the level of the proximal to mid-thigh reveals the prominent bursal extension posteriorly (*) from the joint; the bursa contains several calcifications. (g, h) Photographs of gross specimens show multiple chondral bodies from the joint (arrows in g) and from the bursa (* in h) with thickened, synovially lined wall (between arrows in h).

View larger version (107K): [in this window] [in a new window] [Download PPT slide]   Figure 4b.  Primary synovial chondromatosis of the hip with bursal extension in a 27-year-old man with chronic hip pain. (a) Anteroposterior hip radiograph shows a widening right hip joint with subtle acetabular erosion (arrow) and calcifications (arrowheads) most apparent overlying the obturator canal. (b) Axial CT scan reveals a low-attenuation intraarticular mass about the femoral neck (*), extrinsic erosion of bone (solid arrow), and medial extension containing calcification that represents involvement of the obturator externus bursa (open arrow). (c–e) Axial contrast-enhanced T1-weighted with fat suppression (c, 600/20), axial T2-weighted (d, 2500/80), and coronal T1-weighted (e, 800/10) MR images demonstrate the synovial process diffusely involving the joint; low signal intensity is seen with T1-weighting and high signal intensity with T2-weighting (*). Bursal extensions medially and posteriorly are also seen, particularly on the contrast-enhanced image with peripheral and septal enhancement (arrowheads). Lower-signal-intensity regions within the high-signal-intensity abnormality on long TR images and small areas of rimlike enhancement represent osteochondral fragments (arrows in c and d). (f) CT scan obtained at the level of the proximal to mid-thigh reveals the prominent bursal extension posteriorly (*) from the joint; the bursa contains several calcifications. (g, h) Photographs of gross specimens show multiple chondral bodies from the joint (arrows in g) and from the bursa (* in h) with thickened, synovially lined wall (between arrows in h).

View larger version (162K): [in this window] [in a new window] [Download PPT slide]   Figure 4c.  Primary synovial chondromatosis of the hip with bursal extension in a 27-year-old man with chronic hip pain. (a) Anteroposterior hip radiograph shows a widening right hip joint with subtle acetabular erosion (arrow) and calcifications (arrowheads) most apparent overlying the obturator canal. (b) Axial CT scan reveals a low-attenuation intraarticular mass about the femoral neck (*), extrinsic erosion of bone (solid arrow), and medial extension containing calcification that represents involvement of the obturator externus bursa (open arrow). (c–e) Axial contrast-enhanced T1-weighted with fat suppression (c, 600/20), axial T2-weighted (d, 2500/80), and coronal T1-weighted (e, 800/10) MR images demonstrate the synovial process diffusely involving the joint; low signal intensity is seen with T1-weighting and high signal intensity with T2-weighting (*). Bursal extensions medially and posteriorly are also seen, particularly on the contrast-enhanced image with peripheral and septal enhancement (arrowheads). Lower-signal-intensity regions within the high-signal-intensity abnormality on long TR images and small areas of rimlike enhancement represent osteochondral fragments (arrows in c and d). (f) CT scan obtained at the level of the proximal to mid-thigh reveals the prominent bursal extension posteriorly (*) from the joint; the bursa contains several calcifications. (g, h) Photographs of gross specimens show multiple chondral bodies from the joint (arrows in g) and from the bursa (* in h) with thickened, synovially lined wall (between arrows in h).

View larger version (130K): [in this window] [in a new window] [Download PPT slide]   Figure 4d.  Primary synovial chondromatosis of the hip with bursal extension in a 27-year-old man with chronic hip pain. (a) Anteroposterior hip radiograph shows a widening right hip joint with subtle acetabular erosion (arrow) and calcifications (arrowheads) most apparent overlying the obturator canal. (b) Axial CT scan reveals a low-attenuation intraarticular mass about the femoral neck (*), extrinsic erosion of bone (solid arrow), and medial extension containing calcification that represents involvement of the obturator externus bursa (open arrow). (c–e) Axial contrast-enhanced T1-weighted with fat suppression (c, 600/20), axial T2-weighted (d, 2500/80), and coronal T1-weighted (e, 800/10) MR images demonstrate the synovial process diffusely involving the joint; low signal intensity is seen with T1-weighting and high signal intensity with T2-weighting (*). Bursal extensions medially and posteriorly are also seen, particularly on the contrast-enhanced image with peripheral and septal enhancement (arrowheads). Lower-signal-intensity regions within the high-signal-intensity abnormality on long TR images and small areas of rimlike enhancement represent osteochondral fragments (arrows in c and d). (f) CT scan obtained at the level of the proximal to mid-thigh reveals the prominent bursal extension posteriorly (*) from the joint; the bursa contains several calcifications. (g, h) Photographs of gross specimens show multiple chondral bodies from the joint (arrows in g) and from the bursa (* in h) with thickened, synovially lined wall (between arrows in h).

View larger version (176K): [in this window] [in a new window] [Download PPT slide]   Figure 4e.  Primary synovial chondromatosis of the hip with bursal extension in a 27-year-old man with chronic hip pain. (a) Anteroposterior hip radiograph shows a widening right hip joint with subtle acetabular erosion (arrow) and calcifications (arrowheads) most apparent overlying the obturator canal. (b) Axial CT scan reveals a low-attenuation intraarticular mass about the femoral neck (*), extrinsic erosion of bone (solid arrow), and medial extension containing calcification that represents involvement of the obturator externus bursa (open arrow). (c–e) Axial contrast-enhanced T1-weighted with fat suppression (c, 600/20), axial T2-weighted (d, 2500/80), and coronal T1-weighted (e, 800/10) MR images demonstrate the synovial process diffusely involving the joint; low signal intensity is seen with T1-weighting and high signal intensity with T2-weighting (*). Bursal extensions medially and posteriorly are also seen, particularly on the contrast-enhanced image with peripheral and septal enhancement (arrowheads). Lower-signal-intensity regions within the high-signal-intensity abnormality on long TR images and small areas of rimlike enhancement represent osteochondral fragments (arrows in c and d). (f) CT scan obtained at the level of the proximal to mid-thigh reveals the prominent bursal extension posteriorly (*) from the joint; the bursa contains several calcifications. (g, h) Photographs of gross specimens show multiple chondral bodies from the joint (arrows in g) and from the bursa (* in h) with thickened, synovially lined wall (between arrows in h).

View larger version (99K): [in this window] [in a new window] [Download PPT slide]   Figure 4f.  Primary synovial chondromatosis of the hip with bursal extension in a 27-year-old man with chronic hip pain. (a) Anteroposterior hip radiograph shows a widening right hip joint with subtle acetabular erosion (arrow) and calcifications (arrowheads) most apparent overlying the obturator canal. (b) Axial CT scan reveals a low-attenuation intraarticular mass about the femoral neck (*), extrinsic erosion of bone (solid arrow), and medial extension containing calcification that represents involvement of the obturator externus bursa (open arrow). (c–e) Axial contrast-enhanced T1-weighted with fat suppression (c, 600/20), axial T2-weighted (d, 2500/80), and coronal T1-weighted (e, 800/10) MR images demonstrate the synovial process diffusely involving the joint; low signal intensity is seen with T1-weighting and high signal intensity with T2-weighting (*). Bursal extensions medially and posteriorly are also seen, particularly on the contrast-enhanced image with peripheral and septal enhancement (arrowheads). Lower-signal-intensity regions within the high-signal-intensity abnormality on long TR images and small areas of rimlike enhancement represent osteochondral fragments (arrows in c and d). (f) CT scan obtained at the level of the proximal to mid-thigh reveals the prominent bursal extension posteriorly (*) from the joint; the bursa contains several calcifications. (g, h) Photographs of gross specimens show multiple chondral bodies from the joint (arrows in g) and from the bursa (* in h) with thickened, synovially lined wall (between arrows in h).

View larger version (141K): [in this window] [in a new window] [Download PPT slide]   Figure 4g.  Primary synovial chondromatosis of the hip with bursal extension in a 27-year-old man with chronic hip pain. (a) Anteroposterior hip radiograph shows a widening right hip joint with subtle acetabular erosion (arrow) and calcifications (arrowheads) most apparent overlying the obturator canal. (b) Axial CT scan reveals a low-attenuation intraarticular mass about the femoral neck (*), extrinsic erosion of bone (solid arrow), and medial extension containing calcification that represents involvement of the obturator externus bursa (open arrow). (c–e) Axial contrast-enhanced T1-weighted with fat suppression (c, 600/20), axial T2-weighted (d, 2500/80), and coronal T1-weighted (e, 800/10) MR images demonstrate the synovial process diffusely involving the joint; low signal intensity is seen with T1-weighting and high signal intensity with T2-weighting (*). Bursal extensions medially and posteriorly are also seen, particularly on the contrast-enhanced image with peripheral and septal enhancement (arrowheads). Lower-signal-intensity regions within the high-signal-intensity abnormality on long TR images and small areas of rimlike enhancement represent osteochondral fragments (arrows in c and d). (f) CT scan obtained at the level of the proximal to mid-thigh reveals the prominent bursal extension posteriorly (*) from the joint; the bursa contains several calcifications. (g, h) Photographs of gross specimens show multiple chondral bodies from the joint (arrows in g) and from the bursa (* in h) with thickened, synovially lined wall (between arrows in h).

View larger version (134K): [in this window] [in a new window] [Download PPT slide]   Figure 4h.  Primary synovial chondromatosis of the hip with bursal extension in a 27-year-old man with chronic hip pain. (a) Anteroposterior hip radiograph shows a widening right hip joint with subtle acetabular erosion (arrow) and calcifications (arrowheads) most apparent overlying the obturator canal. (b) Axial CT scan reveals a low-attenuation intraarticular mass about the femoral neck (*), extrinsic erosion of bone (solid arrow), and medial extension containing calcification that represents involvement of the obturator externus bursa (open arrow). (c–e) Axial contrast-enhanced T1-weighted with fat suppression (c, 600/20), axial T2-weighted (d, 2500/80), and coronal T1-weighted (e, 800/10) MR images demonstrate the synovial process diffusely involving the joint; low signal intensity is seen with T1-weighting and high signal intensity with T2-weighting (*). Bursal extensions medially and posteriorly are also seen, particularly on the contrast-enhanced image with peripheral and septal enhancement (arrowheads). Lower-signal-intensity regions within the high-signal-intensity abnormality on long TR images and small areas of rimlike enhancement represent osteochondral fragments (arrows in c and d). (f) CT scan obtained at the level of the proximal to mid-thigh reveals the prominent bursal extension posteriorly (*) from the joint; the bursa contains several calcifications. (g, h) Photographs of gross specimens show multiple chondral bodies from the joint (arrows in g) and from the bursa (* in h) with thickened, synovially lined wall (between arrows in h).

View larger version (111K): [in this window] [in a new window] [Download PPT slide]   Figure 5a.  Primary synovial chondromatosis of the temporomandibular joint in a 63-year-old woman with articular crepitus and reduced range of motion. (a, b) Axial (a) and coronal (b) CT images show extensive ring-and-arc mineralization (large arrows) that represents enchondral ossification of the multiple intraarticular chondral bodies (small arrows). The joint is mildly widened. (c) Intraoperative photograph demonstrates open arthrotomy with detection of multiple intraarticular osteochondral fragments (arrowheads). (d) Photograph shows the débrided fragments (arrows). Scale is in centimeters.

View larger version (108K): [in this window] [in a new window] [Download PPT slide]   Figure 5b.  Primary synovial chondromatosis of the temporomandibular joint in a 63-year-old woman with articular crepitus and reduced range of motion. (a, b) Axial (a) and coronal (b) CT images show extensive ring-and-arc mineralization (large arrows) that represents enchondral ossification of the multiple intraarticular chondral bodies (small arrows). The joint is mildly widened. (c) Intraoperative photograph demonstrates open arthrotomy with detection of multiple intraarticular osteochondral fragments (arrowheads). (d) Photograph shows the débrided fragments (arrows). Scale is in centimeters.

View larger version (139K): [in this window] [in a new window] [Download PPT slide]   Figure 5c.  Primary synovial chondromatosis of the temporomandibular joint in a 63-year-old woman with articular crepitus and reduced range of motion. (a, b) Axial (a) and coronal (b) CT images show extensive ring-and-arc mineralization (large arrows) that represents enchondral ossification of the multiple intraarticular chondral bodies (small arrows). The joint is mildly widened. (c) Intraoperative photograph demonstrates open arthrotomy with detection of multiple intraarticular osteochondral fragments (arrowheads). (d) Photograph shows the débrided fragments (arrows). Scale is in centimeters.

View larger version (134K): [in this window] [in a new window] [Download PPT slide]   Figure 5d.  Primary synovial chondromatosis of the temporomandibular joint in a 63-year-old woman with articular crepitus and reduced range of motion. (a, b) Axial (a) and coronal (b) CT images show extensive ring-and-arc mineralization (large arrows) that represents enchondral ossification of the multiple intraarticular chondral bodies (small arrows). The joint is mildly widened. (c) Intraoperative photograph demonstrates open arthrotomy with detection of multiple intraarticular osteochondral fragments (arrowheads). (d) Photograph shows the débrided fragments (arrows). Scale is in centimeters.

View larger version (49K): [in this window] [in a new window] [Download PPT slide]   Figure 6a.  Tenosynovial chondromatosis of the flexor tendon sheath of the fifth finger in a 46-year-old man. (a) Oblique radiograph of the fifth finger shows multifocal calcification along the flexor tendon distribution that results from enchondral ossification (arrows). (b, c) Coronal contrast-enhanced, fat-suppressed T1-weighted (b, 416/13) and axial T1-weighted (c, top, 600/14) and T2-weighted with fat suppression (c, bottom, 4316/103) MR images reveal high-signal-intensity fluid about the flexor tendon (small arrowheads in c) with low-signal-intensity osteochondral fragments (large arrowhead in c) within the synovial sheath. Peripheral enhancement about the osteochondral fragments is seen following contrast material administration (arrows in b). (d) Photograph of the gross specimen demonstrates multiple chondral bodies (*) along a tenosynovial sheath (arrowheads).

View larger version (167K): [in this window] [in a new window] [Download PPT slide]   Figure 6b.  Tenosynovial chondromatosis of the flexor tendon sheath of the fifth finger in a 46-year-old man. (a) Oblique radiograph of the fifth finger shows multifocal calcification along the flexor tendon distribution that results from enchondral ossification (arrows). (b, c) Coronal contrast-enhanced, fat-suppressed T1-weighted (b, 416/13) and axial T1-weighted (c, top, 600/14) and T2-weighted with fat suppression (c, bottom, 4316/103) MR images reveal high-signal-intensity fluid about the flexor tendon (small arrowheads in c) with low-signal-intensity osteochondral fragments (large arrowhead in c) within the synovial sheath. Peripheral enhancement about the osteochondral fragments is seen following contrast material administration (arrows in b). (d) Photograph of the gross specimen demonstrates multiple chondral bodies (*) along a tenosynovial sheath (arrowheads).

View larger version (133K): [in this window] [in a new window] [Download PPT slide]   Figure 6c.  Tenosynovial chondromatosis of the flexor tendon sheath of the fifth finger in a 46-year-old man. (a) Oblique radiograph of the fifth finger shows multifocal calcification along the flexor tendon distribution that results from enchondral ossification (arrows). (b, c) Coronal contrast-enhanced, fat-suppressed T1-weighted (b, 416/13) and axial T1-weighted (c, top, 600/14) and T2-weighted with fat suppression (c, bottom, 4316/103) MR images reveal high-signal-intensity fluid about the flexor tendon (small arrowheads in c) with low-signal-intensity osteochondral fragments (large arrowhead in c) within the synovial sheath. Peripheral enhancement about the osteochondral fragments is seen following contrast material administration (arrows in b). (d) Photograph of the gross specimen demonstrates multiple chondral bodies (*) along a tenosynovial sheath (arrowheads).

View larger version (52K): [in this window] [in a new window] [Download PPT slide]   Figure 6d.  Tenosynovial chondromatosis of the flexor tendon sheath of the fifth finger in a 46-year-old man. (a) Oblique radiograph of the fifth finger shows multifocal calcification along the flexor tendon distribution that results from enchondral ossification (arrows). (b, c) Coronal contrast-enhanced, fat-suppressed T1-weighted (b, 416/13) and axial T1-weighted (c, top, 600/14) and T2-weighted with fat suppression (c, bottom, 4316/103) MR images reveal high-signal-intensity fluid about the flexor tendon (small arrowheads in c) with low-signal-intensity osteochondral fragments (large arrowhead in c) within the synovial sheath. Peripheral enhancement about the osteochondral fragments is seen following contrast material administration (arrows in b). (d) Photograph of the gross specimen demonstrates multiple chondral bodies (*) along a tenosynovial sheath (arrowheads).

View larger version (100K): [in this window] [in a new window] [Download PPT slide]   Figure 7a.  Chondromatosis involving the tenosynovium of the long head biceps tendon in a 32-year-old woman with shoulder pain. (a) Anteroposterior radiograph of the shoulder with internal rotation shows multiple small calcifications medially (arrow). (b) Coronal T1-weighted (733/15) MR image reveals a fusiform-shaped, intermediate-signal-intensity soft-tissue mass (*). (c, d) Axial proton-density–weighted (c, 4000/13) and coronal T2-weighted (d, 2000/90) MR images reveal increased signal intensity of the mass (*) with internal, small, intermediate-signal-intensity foci (arrowheads in d) representing multiple chondral bodies within the distended biceps tendon sheath. The process is seen surrounding the biceps tendon (arrow). (e) Photograph of a coronally sectioned gross specimen reveals the mass (*) representing the distended tenosynovial sheath about the biceps tendon (large arrow) extending superiorly. Innumerable chondral bodies are seen within the distended sheath (small arrows). Scale is in centimeters.

View larger version (115K): [in this window] [in a new window] [Download PPT slide]   Figure 7b.  Chondromatosis involving the tenosynovium of the long head biceps tendon in a 32-year-old woman with shoulder pain. (a) Anteroposterior radiograph of the shoulder with internal rotation shows multiple small calcifications medially (arrow). (b) Coronal T1-weighted (733/15) MR image reveals a fusiform-shaped, intermediate-signal-intensity soft-tissue mass (*). (c, d) Axial proton-density–weighted (c, 4000/13) and coronal T2-weighted (d, 2000/90) MR images reveal increased signal intensity of the mass (*) with internal, small, intermediate-signal-intensity foci (arrowheads in d) representing multiple chondral bodies within the distended biceps tendon sheath. The process is seen surrounding the biceps tendon (arrow). (e) Photograph of a coronally sectioned gross specimen reveals the mass (*) representing the distended tenosynovial sheath about the biceps tendon (large arrow) extending superiorly. Innumerable chondral bodies are seen within the distended sheath (small arrows). Scale is in centimeters.

View larger version (114K): [in this window] [in a new window] [Download PPT slide]   Figure 7c.  Chondromatosis involving the tenosynovium of the long head biceps tendon in a 32-year-old woman with shoulder pain. (a) Anteroposterior radiograph of the shoulder with internal rotation shows multiple small calcifications medially (arrow). (b) Coronal T1-weighted (733/15) MR image reveals a fusiform-shaped, intermediate-signal-intensity soft-tissue mass (*). (c, d) Axial proton-density–weighted (c, 4000/13) and coronal T2-weighted (d, 2000/90) MR images reveal increased signal intensity of the mass (*) with internal, small, intermediate-signal-intensity foci (arrowheads in d) representing multiple chondral bodies within the distended biceps tendon sheath. The process is seen surrounding the biceps tendon (arrow). (e) Photograph of a coronally sectioned gross specimen reveals the mass (*) representing the distended tenosynovial sheath about the biceps tendon (large arrow) extending superiorly. Innumerable chondral bodies are seen within the distended sheath (small arrows). Scale is in centimeters.

View larger version (111K): [in this window] [in a new window] [Download PPT slide]   Figure 7d.  Chondromatosis involving the tenosynovium of the long head biceps tendon in a 32-year-old woman with shoulder pain. (a) Anteroposterior radiograph of the shoulder with internal rotation shows multiple small calcifications medially (arrow). (b) Coronal T1-weighted (733/15) MR image reveals a fusiform-shaped, intermediate-signal-intensity soft-tissue mass (*). (c, d) Axial proton-density–weighted (c, 4000/13) and coronal T2-weighted (d, 2000/90) MR images reveal increased signal intensity of the mass (*) with internal, small, intermediate-signal-intensity foci (arrowheads in d) representing multiple chondral bodies within the distended biceps tendon sheath. The process is seen surrounding the biceps tendon (arrow). (e) Photograph of a coronally sectioned gross specimen reveals the mass (*) representing the distended tenosynovial sheath about the biceps tendon (large arrow) extending superiorly. Innumerable chondral bodies are seen within the distended sheath (small arrows). Scale is in centimeters.

View larger version (132K): [in this window] [in a new window] [Download PPT slide]   Figure 7e.  Chondromatosis involving the tenosynovium of the long head biceps tendon in a 32-year-old woman with shoulder pain. (a) Anteroposterior radiograph of the shoulder with internal rotation shows multiple small calcifications medially (arrow). (b) Coronal T1-weighted (733/15) MR image reveals a fusiform-shaped, intermediate-signal-intensity soft-tissue mass (*). (c, d) Axial proton-density–weighted (c, 4000/13) and coronal T2-weighted (d, 2000/90) MR images reveal increased signal intensity of the mass (*) with internal, small, intermediate-signal-intensity foci (arrowheads in d) representing multiple chondral bodies within the distended biceps tendon sheath. The process is seen surrounding the biceps tendon (arrow). (e) Photograph of a coronally sectioned gross specimen reveals the mass (*) representing the distended tenosynovial sheath about the biceps tendon (large arrow) extending superiorly. Innumerable chondral bodies are seen within the distended sheath (small arrows). Scale is in centimeters.

View larger version (117K): [in this window] [in a new window] [Download PPT slide]   Figure 8a.  Bursal chondromatosis involving the subscapularis bursa in a 46-year-old man who presented with an upper chest wall mass. (a) Anteroposterior radiograph of the shoulder shows an increased space between the undersurface of the clavicle and coracoid without definite calcifications. Note the extrinsic erosion of the clavicle (arrow). (b) US scan reveals the heterogeneous soft-tissue mass (large arrowheads) with small hyperechoic foci (small arrowheads), several of which demonstrate posterior acoustic shadowing, a finding consistent with calcification. (c) CT scan demonstrates the soft-tissue mass between the clavicle (cl) and coracoid (co). The mass contains multiple small foci (arrows), several of which are calcified (arrowheads). (d) Photograph of the gross specimen shows innumerable small chondral bodies, all of similar size and shape, within a portion of the smooth, thin-walled bursal sac (*) lined by synovium.

View larger version (128K): [in this window] [in a new window] [Download PPT slide]   Figure 8b.  Bursal chondromatosis involving the subscapularis bursa in a 46-year-old man who presented with an upper chest wall mass. (a) Anteroposterior radiograph of the shoulder shows an increased space between the undersurface of the clavicle and coracoid without definite calcifications. Note the extrinsic erosion of the clavicle (arrow). (b) US scan reveals the heterogeneous soft-tissue mass (large arrowheads) with small hyperechoic foci (small arrowheads), several of which demonstrate posterior acoustic shadowing, a finding consistent with calcification. (c) CT scan demonstrates the soft-tissue mass between the clavicle (cl) and coracoid (co). The mass contains multiple small foci (arrows), several of which are calcified (arrowheads). (d) Photograph of the gross specimen shows innumerable small chondral bodies, all of similar size and shape, within a portion of the smooth, thin-walled bursal sac (*) lined by synovium.

View larger version (146K): [in this window] [in a new window] [Download PPT slide]   Figure 8c.  Bursal chondromatosis involving the subscapularis bursa in a 46-year-old man who presented with an upper chest wall mass. (a) Anteroposterior radiograph of the shoulder shows an increased space between the undersurface of the clavicle and coracoid without definite calcifications. Note the extrinsic erosion of the clavicle (arrow). (b) US scan reveals the heterogeneous soft-tissue mass (large arrowheads) with small hyperechoic foci (small arrowheads), several of which demonstrate posterior acoustic shadowing, a finding consistent with calcification. (c) CT scan demonstrates the soft-tissue mass between the clavicle (cl) and coracoid (co). The mass contains multiple small foci (arrows), several of which are calcified (arrowheads). (d) Photograph of the gross specimen shows innumerable small chondral bodies, all of similar size and shape, within a portion of the smooth, thin-walled bursal sac (*) lined by synovium.

View larger version (114K): [in this window] [in a new window] [Download PPT slide]   Figure 8d.  Bursal chondromatosis involving the subscapularis bursa in a 46-year-old man who presented with an upper chest wall mass. (a) Anteroposterior radiograph of the shoulder shows an increased space between the undersurface of the clavicle and coracoid without definite calcifications. Note the extrinsic erosion of the clavicle (arrow). (b) US scan reveals the heterogeneous soft-tissue mass (large arrowheads) with small hyperechoic foci (small arrowheads), several of which demonstrate posterior acoustic shadowing, a finding consistent with calcification. (c) CT scan demonstrates the soft-tissue mass between the clavicle (cl) and coracoid (co). The mass contains multiple small foci (arrows), several of which are calcified (arrowheads). (d) Photograph of the gross specimen shows innumerable small chondral bodies, all of similar size and shape, within a portion of the smooth, thin-walled bursal sac (*) lined by synovium.

View larger version (58K): [in this window] [in a new window] [Download PPT slide]   Figure 9a.  Bursal chondromatosis involving the cervical spine in a 36-year-old man. (a) Axial CT image shows a mass (arrows) with multiple areas of calcification posteriorly at the C1–2 level. (b, c) Sagittal T1-weighted MR images before (b, left, 550/16) and after intravenous administration of contrast material (b, right, 550/14) and T2-weighted (c, left, 3000/12) and gradient-echo (c, right, 600/15; flip angle, 22°) MR images reveal a soft-tissue mass (*) between the posterior arch of C1 and C2. The mass shows intermediate signal intensity on T1-weighted images and high signal intensity on the T2-weighted and gradient-echo MR images. A focal area of low signal intensity (arrowhead) corresponds to the calcification seen at CT and is accentuated with the gradient-echo sequence (c, right). Contrast-enhanced MR image (b, right) demonstrates a peripheral and septal enhancement pattern (arrows). (d) Photograph of the gross specimen shows a multilobulated margin typical of hyaline cartilage neoplastic growth.

View larger version (75K): [in this window] [in a new window] [Download PPT slide]   Figure 9b.  Bursal chondromatosis involving the cervical spine in a 36-year-old man. (a) Axial CT image shows a mass (arrows) with multiple areas of calcification posteriorly at the C1–2 level. (b, c) Sagittal T1-weighted MR images before (b, left, 550/16) and after intravenous administration of contrast material (b, right, 550/14) and T2-weighted (c, left, 3000/12) and gradient-echo (c, right, 600/15; flip angle, 22°) MR images reveal a soft-tissue mass (*) between the posterior arch of C1 and C2. The mass shows intermediate signal intensity on T1-weighted images and high signal intensity on the T2-weighted and gradient-echo MR images. A focal area of low signal intensity (arrowhead) corresponds to the calcification seen at CT and is accentuated with the gradient-echo sequence (c, right). Contrast-enhanced MR image (b, right) demonstrates a peripheral and septal enhancement pattern (arrows). (d) Photograph of the gross specimen shows a multilobulated margin typical of hyaline cartilage neoplastic growth.

View larger version (73K): [in this window] [in a new window] [Download PPT slide]   Figure 9c.  Bursal chondromatosis involving the cervical spine in a 36-year-old man. (a) Axial CT image shows a mass (arrows) with multiple areas of calcification posteriorly at the C1–2 level. (b, c) Sagittal T1-weighted MR images before (b, left, 550/16) and after intravenous administration of contrast material (b, right, 550/14) and T2-weighted (c, left, 3000/12) and gradient-echo (c, right, 600/15; flip angle, 22°) MR images reveal a soft-tissue mass (*) between the posterior arch of C1 and C2. The mass shows intermediate signal intensity on T1-weighted images and high signal intensity on the T2-weighted and gradient-echo MR images. A focal area of low signal intensity (arrowhead) corresponds to the calcification seen at CT and is accentuated with the gradient-echo sequence (c, right). Contrast-enhanced MR image (b, right) demonstrates a peripheral and septal enhancement pattern (arrows). (d) Photograph of the gross specimen shows a multilobulated margin typical of hyaline cartilage neoplastic growth.

View larger version (136K): [in this window] [in a new window] [Download PPT slide]   Figure 9d.  Bursal chondromatosis involving the cervical spine in a 36-year-old man. (a) Axial CT image shows a mass (arrows) with multiple areas of calcification posteriorly at the C1–2 level. (b, c) Sagittal T1-weighted MR images before (b, left, 550/16) and after intravenous administration of contrast material (b, right, 550/14) and T2-weighted (c, left, 3000/12) and gradient-echo (c, right, 600/15; flip angle, 22°) MR images reveal a soft-tissue mass (*) between the posterior arch of C1 and C2. The mass shows intermediate signal intensity on T1-weighted images and high signal intensity on the T2-weighted and gradient-echo MR images. A focal area of low signal intensity (arrowhead) corresponds to the calcification seen at CT and is accentuated with the gradient-echo sequence (c, right). Contrast-enhanced MR image (b, right) demonstrates a peripheral and septal enhancement pattern (arrows). (d) Photograph of the gross specimen shows a multilobulated margin typical of hyaline cartilage neoplastic growth.

	Pathologic Features

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Clinical Characteristics Pathologic Features Imaging Features Treatment and Prognosis Malignant Transformation of... Summary References

 
The gross pathologic appearance of primary synovial chondromatosis consists of hyperplastic synovium covering bluish white, multilobulated, nodular projections of hyaline cartilage diffusely involving the entire joint surface (2,7–9,42) (Fig 10). These nodules may be very numerous and give a "cobblestone" appearance to the synovium. The subsynovial lobular nodules of hyaline cartilage may extend into adjacent soft tissues and bursae and may extrinsically erode bone. A localized, intraarticular form of this disease is extremely rarely reported, and its existence is controversial. The pathologic appearance of extraarticular (tenosynovial or bursal) chondromatosis is identical to that of intraarticular disease, but extraarticular disease involves the subsynovium that extends about bursae or along tendon sheaths (7–9,36). The subsynovial nodules of hyaline cartilage may detach from the synovium to lie within the joint, bursa, or tendon sheath. These chondral bodies may reattach to the synovium and be reabsorbed or be loose within the affected space. Because cartilage is nourished by synovial fluid, the chondral bodies may grow and gradually increase in size. The chondral bodies in the joint space, bursa, or tendon sheath are usually similar in size (ranging from a few millimeters to several centimeters) and shape, which suggests they originate within a similar time frame (Fig 10). Although the number of chondral bodies vary widely from only several to over 1000, they are most commonly numerous (2,7–9). Fusion or coalescence of multiple chondral bodies may occur, creating a "giant" or "massive" (up to 20 cm in diameter) conglomerate appearance (43).

View larger version (107K): [in this window] [in a new window] [Download PPT slide]   Figure 10a.  Pathologic appearance of primary synovial chondromatosis. (a) Photograph of a gross specimen shows innumerable white osteochondral bodies (*), all of similar size and shape, within a joint. (b) Photograph of a whole-mounted specimen (H-E stain) reveals the typical lobulated growth of all hyaline cartilage neoplastic processes (*) beneath synovial lining (small arrows) and regions of synovial hyperplasia (small arrowheads) with multiple blue chondral bodies (*), several of which are surrounded by pink enchondral bone formation (large arrowheads). The peripheral bone formation (radiopaque on radiographs) surrounding the radiolucent cartilage nodules creates the characteristic ring-and-arc calcification of chondroid neoplasms seen at radiography. (c) Photomicrograph (original magnification, x200; H-E stain) shows the synovial proliferation (arrows) with subsynovial cartilaginous nodule formation (*), the multiplicity of which is best depicted in the inset (lower left; original magnification, x300; H-E stain). (d) High-power photomicrograph (original magnification, x400; H-E stain) of one of the cartilage nodules reveals multiple binucleate cells (arrows), nuclear crowding, and atypia, findings that might suggest a more aggressive process.

View larger version (147K): [in this window] [in a new window] [Download PPT slide]   Figure 10b.  Pathologic appearance of primary synovial chondromatosis. (a) Photograph of a gross specimen shows innumerable white osteochondral bodies (*), all of similar size and shape, within a joint. (b) Photograph of a whole-mounted specimen (H-E stain) reveals the typical lobulated growth of all hyaline cartilage neoplastic processes (*) beneath synovial lining (small arrows) and regions of synovial hyperplasia (small arrowheads) with multiple blue chondral bodies (*), several of which are surrounded by pink enchondral bone formation (large arrowheads). The peripheral bone formation (radiopaque on radiographs) surrounding the radiolucent cartilage nodules creates the characteristic ring-and-arc calcification of chondroid neoplasms seen at radiography. (c) Photomicrograph (original magnification, x200; H-E stain) shows the synovial proliferation (arrows) with subsynovial cartilaginous nodule formation (*), the multiplicity of which is best depicted in the inset (lower left; original magnification, x300; H-E stain). (d) High-power photomicrograph (original magnification, x400; H-E stain) of one of the cartilage nodules reveals multiple binucleate cells (arrows), nuclear crowding, and atypia, findings that might suggest a more aggressive process.

View larger version (109K): [in this window] [in a new window] [Download PPT slide]   Figure 10c.  Pathologic appearance of primary synovial chondromatosis. (a) Photograph of a gross specimen shows innumerable white osteochondral bodies (*), all of similar size and shape, within a joint. (b) Photograph of a whole-mounted specimen (H-E stain) reveals the typical lobulated growth of all hyaline cartilage neoplastic processes (*) beneath synovial lining (small arrows) and regions of synovial hyperplasia (small arrowheads) with multiple blue chondral bodies (*), several of which are surrounded by pink enchondral bone formation (large arrowheads). The peripheral bone formation (radiopaque on radiographs) surrounding the radiolucent cartilage nodules creates the characteristic ring-and-arc calcification of chondroid neoplasms seen at radiography. (c) Photomicrograph (original magnification, x200; H-E stain) shows the synovial proliferation (arrows) with subsynovial cartilaginous nodule formation (*), the multiplicity of which is best depicted in the inset (lower left; original magnification, x300; H-E stain). (d) High-power photomicrograph (original magnification, x400; H-E stain) of one of the cartilage nodules reveals multiple binucleate cells (arrows), nuclear crowding, and atypia, findings that might suggest a more aggressive process.

View larger version (118K): [in this window] [in a new window] [Download PPT slide]   Figure 10d.  Pathologic appearance of primary synovial chondromatosis. (a) Photograph of a gross specimen shows innumerable white osteochondral bodies (*), all of similar size and shape, within a joint. (b) Photograph of a whole-mounted specimen (H-E stain) reveals the typical lobulated growth of all hyaline cartilage neoplastic processes (*) beneath synovial lining (small arrows) and regions of synovial hyperplasia (small arrowheads) with multiple blue chondral bodies (*), several of which are surrounded by pink enchondral bone formation (large arrowheads). The peripheral bone formation (radiopaque on radiographs) surrounding the radiolucent cartilage nodules creates the characteristic ring-and-arc calcification of chondroid neoplasms seen at radiography. (c) Photomicrograph (original magnification, x200; H-E stain) shows the synovial proliferation (arrows) with subsynovial cartilaginous nodule formation (*), the multiplicity of which is best depicted in the inset (lower left; original magnification, x300; H-E stain). (d) High-power photomicrograph (original magnification, x400; H-E stain) of one of the cartilage nodules reveals multiple binucleate cells (arrows), nuclear crowding, and atypia, findings that might suggest a more aggressive process.

View larger version (133K): [in this window] [in a new window] [Download PPT slide]   Figure 11a.  Recurrent primary synovial chondromatosis of the hip with secondary osteoarthritis in a 29-year-old man. (a) Anteroposterior radiograph of the hip shows multiple calcified masses about the hip (arrows) with superior joint space narrowing resulting from secondary osteoarthritis. A medial conglomerate area reveals enchondral ossification (*). At this recurrence, biopsy results were misinterpreted histologically as representing sarcomatous transformation to chondrosarcoma and led to treatment with hemipelvectomy. (b–d) Specimen radiograph (b) and photographs of coronally sectioned gross specimen (c) and whole-mounted specimen (d, H-E stain) reveal multiple chondral bodies (c), several of which are causing extrinsic erosion of the femoral neck without marrow invasion (arrowheads), enchondral ossification of the conglomerate chondral mass medially (*), and osteoarthritic changes with cartilage thinning superiorly (arrows). Pathologic re-evaluation demonstrated only recurrent synovial chondromatosis, without evidence of sarcomatous transformation.

View larger version (152K): [in this window] [in a new window] [Download PPT slide]   Figure 11b.  Recurrent primary synovial chondromatosis of the hip with secondary osteoarthritis in a 29-year-old man. (a) Anteroposterior radiograph of the hip shows multiple calcified masses about the hip (arrows) with superior joint space narrowing resulting from secondary osteoarthritis. A medial conglomerate area reveals enchondral ossification (*). At this recurrence, biopsy results were misinterpreted histologically as representing sarcomatous transformation to chondrosarcoma and led to treatment with hemipelvectomy. (b–d) Specimen radiograph (b) and photographs of coronally sectioned gross specimen (c) and whole-mounted specimen (d, H-E stain) reveal multiple chondral bodies (c), several of which are causing extrinsic erosion of the femoral neck without marrow invasion (arrowheads), enchondral ossification of the conglomerate chondral mass medially (*), and osteoarthritic changes with cartilage thinning superiorly (arrows). Pathologic re-evaluation demonstrated only recurrent synovial chondromatosis, without evidence of sarcomatous transformation.

View larger version (123K): [in this window] [in a new window] [Download PPT slide]   Figure 11c.  Recurrent primary synovial chondromatosis of the hip with secondary osteoarthritis in a 29-year-old man. (a) Anteroposterior radiograph of the hip shows multiple calcified masses about the hip (arrows) with superior joint space narrowing resulting from secondary osteoarthritis. A medial conglomerate area reveals enchondral ossification (*). At this recurrence, biopsy results were misinterpreted histologically as representing sarcomatous transformation to chondrosarcoma and led to treatment with hemipelvectomy. (b–d) Specimen radiograph (b) and photographs of coronally sectioned gross specimen (c) and whole-mounted specimen (d, H-E stain) reveal multiple chondral bodies (c), several of which are causing extrinsic erosion of the femoral neck without marrow invasion (arrowheads), enchondral ossification of the conglomerate chondral mass medially (*), and osteoarthritic changes with cartilage thinning superiorly (arrows). Pathologic re-evaluation demonstrated only recurrent synovial chondromatosis, without evidence of sarcomatous transformation.

View larger version (120K): [in this window] [in a new window] [Download PPT slide]   Figure 11d.  Recurrent primary synovial chondromatosis of the hip with secondary osteoarthritis in a 29-year-old man. (a) Anteroposterior radiograph of the hip shows multiple calcified masses about the hip (arrows) with superior joint space narrowing resulting from secondary osteoarthritis. A medial conglomerate area reveals enchondral ossification (*). At this recurrence, biopsy results were misinterpreted histologically as representing sarcomatous transformation to chondrosarcoma and led to treatment with hemipelvectomy. (b–d) Specimen radiograph (b) and photographs of coronally sectioned gross specimen (c) and whole-mounted specimen (d, H-E stain) reveal multiple chondral bodies (c), several of which are causing extrinsic erosion of the femoral neck without marrow invasion (arrowheads), enchondral ossification of the conglomerate chondral mass medially (*), and osteoarthritic changes with cartilage thinning superiorly (arrows). Pathologic re-evaluation demonstrated only recurrent synovial chondromatosis, without evidence of sarcomatous transformation.

In the past, the etiology of primary synovial chondromatosis was variably believed to range from a purely metaplastic process to a true neoplastic disease. However, on the basis of currently known molecular abnormalities, primary synovial chondromatosis is believed to be a benign neoplastic rather than metaplastic disease (27,47–50). As expected, these cytogenetic aberrations are absent in secondary synovial chondromatosis. Hedgehog signaling, measured by its target genes PTC1 and GLI1, and usually involved in development of other cartilaginous neoplasms, may play a role in development of primary synovial chondromatosis (27). In addition, growth factors, such as fibroblast growth factor –2 and –3 (47,48), have been found in primary synovial chondromatosis. The proto-oncogene C-ERBB2 was found in a familial case of two brothers with identical ankle involvement by primary synovial chondromatosis (49). Finally, chromosome 6 abnormalities, identified at cytogenetic and molecular cytogenetic analyses, have been a recurrent finding in primary synovial chondromatosis (50), results that indicate the disease is a neoplastic condition.

The pathologic differential diagnosis of primary synovial chondromatosis includes soft-tissue chondroma, secondary synovial chondromatosis, and intraosseous low-grade chondrosarcoma that extends into the joint. Soft-tissue chondroma can be distinguished from primary synovial chondromatosis on the basis of location (hands and feet predominantly and not intraarticular, intrabursal, or in a tendon sheath), composition of a solitary nodule of hyaline cartilage, and lack of a synovial lining surrounding the lesion (3,7–10,51). Secondary synovial chondromatosis (associated with mechanical or arthritic conditions) can be distinguished histologically from primary synovial chondromatosis by the reactive, proliferative chondral bodies that often have a central nidus of nonneoplastic hypocellular cartilage that grows in concentric rings (frequently multiple or with a layered effect), lack of atypia, and presence of fragments of articular hyaline cartilage (1,3,10) (Fig 12). In addition, there are a smaller number of chondral fragments with variable size. The underlying joint abnormality (typically osteoarthritis) is also usually readily apparent both clinically and radiologically (Fig 12). Chondrosarcoma arising in bone and extending into the joint can be radiologically distinguished from primary synovial chondromatosis (the histologic atypia of these two conditions may appear similar).

View larger version (148K): [in this window] [in a new window] [Download PPT slide]   Figure 12a.  Secondary synovial chondromatosis of the knee in a 70-year-old woman. (a) Lateral radiograph of the knee shows patellofemoral and tibiofemoral osteoarthritis. Several intraarticular osteochondral bodies of different sizes and shapes are seen (large arrows). The largest osteochondral fragment reveals two rings of calcification superiorly (small arrows); these features are typical of secondary chondromatosis. (b) Photomicrograph (original magnification, x100; H-E stain) of an intraarticular osteochondral fragment from a different patient demonstrates devitalized cartilage centrally (*) and several ringlike areas of mineralization more peripherally (between arrowheads), findings that correspond to the radiographic appearance.

View larger version (104K): [in this window] [in a new window] [Download PPT slide]   Figure 12b.  Secondary synovial chondromatosis of the knee in a 70-year-old woman. (a) Lateral radiograph of the knee shows patellofemoral and tibiofemoral osteoarthritis. Several intraarticular osteochondral bodies of different sizes and shapes are seen (large arrows). The largest osteochondral fragment reveals two rings of calcification superiorly (small arrows); these features are typical of secondary chondromatosis. (b) Photomicrograph (original magnification, x100; H-E stain) of an intraarticular osteochondral fragment from a different patient demonstrates devitalized cartilage centrally (*) and several ringlike areas of mineralization more peripherally (between arrowheads), findings that correspond to the radiographic appearance.

	Imaging Features

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View larger version (101K): [in this window] [in a new window] [Download PPT slide]   Figure 13a.  Primary synovial chondromatosis of the shoulder in a 19-year-old woman. (a) Anteroposterior radiograph of the shoulder shows multiple intraarticular osteochondral bodies (arrows) with a target appearance (single peripheral rim and central dot of calcification). (b) CT scan demonstrates the target appearance more clearly (arrows). (c, d) Axial T1-weighted (c, 500/20) and T2-weighted (d, 2000/90) MR images also reveal the target appearance with several rings (arrows) on the short TR image. The osteochondral bodies appear as filling defects (arrowheads) with surrounding high signal intensity on the long TR image. (e) Photograph of a whole-mounted specimen (H-E stain) demonstrates the cause of the target appearance of the intraarticular bodies: Pink areas represent cortical bone formation resulting from enchondral ossification (peripheral areas between arrowheads correspond to rim calcification); blue areas (b) are cartilage (which appears radiolucent at imaging); purple areas (c) are caused by dystrophic mineralization of cartilage centrally (and correspond to central calcification at imaging); and central marrow formation with adipose tissue (arrows) corresponds to imaging appearances better seen in Fig 2b.

View larger version (77K): [in this window] [in a new window] [Download PPT slide]   Figure 13b.  Primary synovial chondromatosis of the shoulder in a 19-year-old woman. (a) Anteroposterior radiograph of the shoulder shows multiple intraarticular osteochondral bodies (arrows) with a target appearance (single peripheral rim and central dot of calcification). (b) CT scan demonstrates the target appearance more clearly (arrows). (c, d) Axial T1-weighted (c, 500/20) and T2-weighted (d, 2000/90) MR images also reveal the target appearance with several rings (arrows) on the short TR image. The osteochondral bodies appear as filling defects (arrowheads) with surrounding high signal intensity on the long TR image. (e) Photograph of a whole-mounted specimen (H-E stain) demonstrates the cause of the target appearance of the intraarticular bodies: Pink areas represent cortical bone formation resulting from enchondral ossification (peripheral areas between arrowheads correspond to rim calcification); blue areas (b) are cartilage (which appears radiolucent at imaging); purple areas (c) are caused by dystrophic mineralization of cartilage centrally (and correspond to central calcification at imaging); and central marrow formation with adipose tissue (arrows) corresponds to imaging appearances better seen in Fig 2b.

View larger version (107K): [in this window] [in a new window] [Download PPT slide]   Figure 13c.  Primary synovial chondromatosis of the shoulder in a 19-year-old woman. (a) Anteroposterior radiograph of the shoulder shows multiple intraarticular osteochondral bodies (arrows) with a target appearance (single peripheral rim and central dot of calcification). (b) CT scan demonstrates the target appearance more clearly (arrows). (c, d) Axial T1-weighted (c, 500/20) and T2-weighted (d, 2000/90) MR images also reveal the target appearance with several rings (arrows) on the short TR image. The osteochondral bodies appear as filling defects (arrowheads) with surrounding high signal intensity on the long TR image. (e) Photograph of a whole-mounted specimen (H-E stain) demonstrates the cause of the target appearance of the intraarticular bodies: Pink areas represent cortical bone formation resulting from enchondral ossification (peripheral areas between arrowheads correspond to rim calcification); blue areas (b) are cartilage (which appears radiolucent at imaging); purple areas (c) are caused by dystrophic mineralization of cartilage centrally (and correspond to central calcification at imaging); and central marrow formation with adipose tissue (arrows) corresponds to imaging appearances better seen in Fig 2b.

View larger version (88K): [in this window] [in a new window] [Download PPT slide]   Figure 13d.  Primary synovial chondromatosis of the shoulder in a 19-year-old woman. (a) Anteroposterior radiograph of the shoulder shows multiple intraarticular osteochondral bodies (arrows) with a target appearance (single peripheral rim and central dot of calcification). (b) CT scan demonstrates the target appearance more clearly (arrows). (c, d) Axial T1-weighted (c, 500/20) and T2-weighted (d, 2000/90) MR images also reveal the target appearance with several rings (arrows) on the short TR image. The osteochondral bodies appear as filling defects (arrowheads) with surrounding high signal intensity on the long TR image. (e) Photograph of a whole-mounted specimen (H-E stain) demonstrates the cause of the target appearance of the intraarticular bodies: Pink areas represent cortical bone formation resulting from enchondral ossification (peripheral areas between arrowheads correspond to rim calcification); blue areas (b) are cartilage (which appears radiolucent at imaging); purple areas (c) are caused by dystrophic mineralization of cartilage centrally (and correspond to central calcification at imaging); and central marrow formation with adipose tissue (arrows) corresponds to imaging appearances better seen in Fig 2b.

View larger version (117K): [in this window] [in a new window] [Download PPT slide]   Figure 13e.  Primary synovial chondromatosis of the shoulder in a 19-year-old woman. (a) Anteroposterior radiograph of the shoulder shows multiple intraarticular osteochondral bodies (arrows) with a target appearance (single peripheral rim and central dot of calcification). (b) CT scan demonstrates the target appearance more clearly (arrows). (c, d) Axial T1-weighted (c, 500/20) and T2-weighted (d, 2000/90) MR images also reveal the target appearance with several rings (arrows) on the short TR image. The osteochondral bodies appear as filling defects (arrowheads) with surrounding high signal intensity on the long TR image. (e) Photograph of a whole-mounted specimen (H-E stain) demonstrates the cause of the target appearance of the intraarticular bodies: Pink areas represent cortical bone formation resulting from enchondral ossification (peripheral areas between arrowheads correspond to rim calcification); blue areas (b) are cartilage (which appears radiolucent at imaging); purple areas (c) are caused by dystrophic mineralization of cartilage centrally (and correspond to central calcification at imaging); and central marrow formation with adipose tissue (arrows) corresponds to imaging appearances better seen in Fig 2b.

View larger version (107K): [in this window] [in a new window] [Download PPT slide]   Figure 14a.  Primary synovial chondromatosis of the ankle in a 25-year-old man. (a) Sagittal CT scan shows an extensive, lobular, low-attenuation mass about the hind foot and ankle (*) with peripheral and septal enhancement (small arrowheads), deep extrinsic erosion of bone (arrows), and subluxation of the talonavicular joint (large arrowhead). (b, c) Sagittal fat-suppressed contrast-enhanced T1-weighted (b, 700/30) and T2-weighted (c, 4000/20) MR images reveal similar features of lobular growth of the neoplasm (*), deep extrinsic erosion of bone without marrow invasion (arrows), and talonavicular joint subluxation (arrowhead). There is peripheral and septal enhancement and high signal intensity on the long TR image.

View larger version (137K): [in this window] [in a new window] [Download PPT slide]   Figure 14b.  Primary synovial chondromatosis of the ankle in a 25-year-old man. (a) Sagittal CT scan shows an extensive, lobular, low-attenuation mass about the hind foot and ankle (*) with peripheral and septal enhancement (small arrowheads), deep extrinsic erosion of bone (arrows), and subluxation of the talonavicular joint (large arrowhead). (b, c) Sagittal fat-suppressed contrast-enhanced T1-weighted (b, 700/30) and T2-weighted (c, 4000/20) MR images reveal similar features of lobular growth of the neoplasm (*), deep extrinsic erosion of bone without marrow invasion (arrows), and talonavicular joint subluxation (arrowhead). There is peripheral and septal enhancement and high signal intensity on the long TR image.

View larger version (133K): [in this window] [in a new window] [Download PPT slide]   Figure 14c.  Primary synovial chondromatosis of the ankle in a 25-year-old man. (a) Sagittal CT scan shows an extensive, lobular, low-attenuation mass about the hind foot and ankle (*) with peripheral and septal enhancement (small arrowheads), deep extrinsic erosion of bone (arrows), and subluxation of the talonavicular joint (large arrowhead). (b, c) Sagittal fat-suppressed contrast-enhanced T1-weighted (b, 700/30) and T2-weighted (c, 4000/20) MR images reveal similar features of lobular growth of the neoplasm (*), deep extrinsic erosion of bone without marrow invasion (arrows), and talonavicular joint subluxation (arrowhead). There is peripheral and septal enhancement and high signal intensity on the long TR image.

Secondary synovial chondromatosis also reveals osteochondral intraarticular fragments; however, these are fewer in number and more variable in size (suggesting various times of origin), compared with the fragments observed in primary disease (1,5,10). In addition, in secondary synovial chondromatosis, several rings of calcification may be identified on radiographs, compared with the single ring seen in primary disease (Fig 12). Radiographic alterations associated with the underlying joint abnormality (most commonly, osteoarthritis) are also apparent and allow secondary disease to be distinguished from primary synovial chondromatosis (Fig 12).

Radiographic findings are normal in 5%–30% of primary intraarticular synovial chondromatosis cases (1,5,7,9,13). Arthrography (typically followed by CT or MR imaging) often reveals diagnostic features, with the multifocal intraarticular chondral bodies seen as numerous, circular filling defects (1,60) (Fig 3). The bone scintigraphic findings in synovial chondromatosis have not been extensively evaluated. However, the reported cases reveal nonspecific but prominent uptake of radionuclide, a finding that reflects the increased turnover of calcium and phosphate (16,20,61) (Fig 3).

The ultrasonographic (US) appearance of synovial chondromatosis has also not been extensively evaluated, except for isolated case reports (62–65). In our experience, US reveals a heterogeneous mass containing foci of hyperechogenicity (Fig 8). These hyperechoic foci represent either the chondral fragments within the joint, bursa, or tendon sheath or fronds of the synovium with underlying cartilage nodule formation. Posterior acoustic shadowing may also be present and related to the hyperechoic foci if there is sufficient mineralization or enchondral bone formation (62–65) (Fig 8). However, extensive mineralization may obscure more characteristic features of lobular contours and the multiplicity of the chondral bodies (5). Depending on the site involved, the intraarticular or intrabursal chondral or osteochondral fragments may change in position during dynamic US examination, a helpful sign that they are indeed loose. Power Doppler sonography has been reported to reveal an avascular process (65).

CT shows low attenuation of nonmineralized regions of synovial thickening owing to associated joint fluid and the high water content of the hyaline cartilage neoplastic process (1,2,7,14,20) (Figs 1, 14). The lobular outer contours, caused by the growth pattern of synovial chondromatosis and common to all hyaline cartilage neoplasms, aid in distinguishing this neoplastic process from synovial fluid. CT is the optimal imaging modality to both detect and characterize calcification, and the vast majority of cases of intraarticular, bursal, and tenosynovial primary synovial chondromatosis reveal this feature (Figs 1, 4, 5). CT is particularly helpful for identifying characteristic ring-and-arc or punctate mineralization and the multiplicity of nodules in cases for which radiographic findings are normal or equivocal due to complex osseous anatomy, such as in the hip or temporomandibular joint (Figs 1, 4, 5). The target appearance observed at radiography may also be seen at CT, and ossification with central yellow marrow (fat attenuation) can also be detected (1,5,66) (Fig 13). Extrinsic erosion of bone is also optimally evaluated with CT, owing to its cross-sectional imaging capabilities. CT may reveal subtle extrinsic erosion not seen or not confidently detected at radiography, even in capacious joints such as the knee (Fig 1). As with radiography, CT does not show marrow invasion (Figs 1, 14). CT may be combined with arthrography to document the location of the chondral nodules as intraarticular, bursal, or tenosynovial (1,5,67). Peripheral and septal enhancement may be seen following intravenous administration of contrast material (Fig 14). This finding represents enhancement of the vascularized synovium and fibrous septations between the relatively avascular cartilaginous nodules.

The MR imaging appearance of primary synovial chondromatosis occurs in three distinct patterns, as described by Kramer and co-workers (68). The most frequent pattern (77% of 21 cases) was characterized as lobulated, homogeneous, intermediate, intraarticular signal intensity similar to that of muscle on T1-weighted images, with high signal intensity on T2-weighted images and focal areas of low signal intensity with all pulse sequences (correlates to Milgram phase 2 lesions) (68) (Figs 6, 7, 9, 13). The areas of signal void corresponded to regions of calcification on radiographs or CT scans and became more conspicuous on gradient-echo MR images owing to magnetic susceptibility effects (68) (Fig 9). The second most common pattern (14% of cases) was similar to the first, but no focal intraarticular areas of low signal intensity (correlates to Milgram phase 1 lesions) and no calcifications were seen on corresponding radiographs or CT scans (68) (Fig 14). The third and final pattern (9% of cases) had features similar to those of the other patterns but also included high-signal-intensity foci isointense relative to fat with a peripheral rim of low signal intensity (68) (Fig 2). This pattern corresponded to foci of enchondral ossification on radiographs or CT (Fig 2). Our experience is similar to that reported by Kramer and colleagues, but with several variations. The signal intensity on T1-weighted images of the nonmineralized regions is frequently lower than that of muscle and similar to that of fluid, rather than intermediate signal intensity; this appearance corresponds to the high water content of the hyaline cartilage neoplastic process seen histologically (69) (Figs 4, 14). We also believe that, in many cases in which radiographs or CT scans show no calcification, close inspection of long TR images reveals small foci (circular or slightly elongated) of slightly lower signal within the overall high signal intensity. We believe these foci correspond to the chondral bodies and refer to this pattern as the "grain of sand" appearance (Figs 4, 7). Similar features are seen in bursal and tenosynovial chondromatosis, and MR imaging is optimal to demonstrate typical bursal location or intimate relationship of the process within the tendon sheath (Figs 6, 7, 9). MR imaging can also depict bursal extension of intraarticular primary synovial chondromatosis (70). This finding is particularly prevalent in the hip and has been detected in 40%–71% of cases with extension into the iliopsoas and obturator externus bursa (71,72) (Fig 4). We have also noted extension along bursae for prominent distances away from the intraarticular component that, if not recognized and treated appropriately, could lead to local recurrence (Fig 4). Additional MR imaging features of primary synovial chondromatosis that were recognized by Kim and colleagues (71) in 15 cases involving the hip include synovial thickening (87%), bone erosion (73% of hip lesions), and conglomeration of intraarticular lesions (73%) (Figs 2, 4, 14). Extrinsic erosion of bone, as seen with other imaging modalities, may be deep, simulating the manifestations of a more aggressive disease process, and MR imaging is optimal for excluding true marrow invasion (Fig 14). As with CT, MR imaging may reveal subtle extrinsic erosion not seen or confidently detected at radiography, even in capacious joints such as the knee (Fig 2). The contrast material enhancement of primary synovial chondromatosis is typical of hyaline cartilage neoplasms, which have a characteristic peripheral and septal pattern (Figs 4, 6, 9). The nonenhancing regions represent the multilobulated areas of hyaline cartilage nodules that are often highlighted following intravenous administration of contrast material (16,55,68,71,72) (Figs 4, 6).

	Treatment and Prognosis

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The treatment of choice for primary synovial chondromatosis, either intraarticular or extraarticular (bursal or tenosynovial), is surgical resection (44,45). The overall recurrence rate for intraarticular disease in larger series appears to range from 3% to 23%, and recurrence may be related to incomplete resection in many cases (19,20,44, 45). However, controversy exists regarding the extent of surgical treatment required for primary synovial chondromatosis, specifically, whether removal of chondral bodies alone is sufficient or whether associated synovectomy is also necessary. Shpitzer and co-workers (73) found no difference in prognosis after a 6-year follow-up for 26 patients who underwent either removal of chondral bodies only or synovectomy as well as chondral fragment removal for primary intraarticular synovial chondromatosis of the knee. Maurice and colleagues (45) showed similar results in a study of 53 patients. However, other researchers have shown that the recurrence rate is higher among patients who undergo chondral body removal only (46,74). Ogilvie-Harris and Saleh (46) reported a 60% recurrence rate among patients managed with loose body removal alone. In contradistinction, patients who underwent associated synovectomy had no recurrences (46,74). These conflicting results may be explained by the differing phases of primary intraarticular synovial chondromatosis as defined by Milgram (44). Milgram advocated synovectomy to treat active phase 1 disease (intrasynovial disease without chondral bodies), synovectomy with removal of chondral fragments for phase 2 disease (transitional form with intrasynovial disease and chondral bodies), and removal of the multiple chondral bodies alone and no synovectomy for phase 3 disease (late inactive disease with chondral bodies but no synovial abnormality) (44). In the study by Milgram (44), no recurrences were seen in 11 cases of phase 3 disease. However, only one case of phase 1 and one case of phase 2 disease had local recurrence, and Milgram’s theory has not been shown to correlate well with prognosis (44). Synovectomy and removal of the chondral bodies are generally regarded as the optimal treatment of intraarticular primary synovial chondromatosis (45,46,74).

The recurrence rate reported for extraarticular primary synovial chondromatosis has varied widely. In the studies by Maurice et al (45) (11 cases) and Roulot and Le Viet (20) (10 cases), there were no local recurrences following surgical resection. However, in a larger series, Fetsch et al (36) showed a local recurrence rate of 88% (14 of 16 patients with follow-up information, or 38% of all patients [14 of 37]) following surgical resection. In this study, seven patients had multiple recurrences (36). Local recurrence is typically seen within 5 years after the initial resection with both intraarticular and extraarticular forms of the disease and can be effectively treated with surgical reexcision (46,75).

With advancement in arthroscopic techniques, there is recent interest in the arthroscopic treatment of this disease. Although arthroscopy can be technically demanding, its use helps avoid the patient morbidity caused by a large, open procedure, easing postoperative rehabilitation. Arthroscopic treatment has been shown to be successful in the knee, hip, shoulder, elbow, and the sub-acromial bursa with very low recurrence rates (2,46,76,77). However, this approach does have limitations and is not free of complications. Extraarticular disease (either primary or due to secondary extension of intraarticular disease), which has been noted in 21%–80% of cases (45,73), is important to detect at imaging evaluation because it cannot be treated through arthroscopic techniques. The success of arthroscopy is also very operator dependent, and iatrogenic damage to the articular cartilage may occur, which can substantially alter the outcome. Local recurrences can be treated effectively with additional surgical intervention (46).

	Malignant Transformation of Primary Synovial Chondromatosis

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Chondrosarcoma arising from primary synovial chondromatosis has been considered an extremely rare event, particularly considering that primary synovial chondromatosis itself is an infrequent condition. However, in 1998 Davis and colleagues (12) reviewed a series of 53 cases of primary synovial chondromatosis and identified three instances of malignant transformation, representing a 5% prevalence. Additional reports in the literature on this process consist primarily of case reports and small series (11,13,78–86). Although synovial chondrosarcoma may arise as the primary condition, the vast majority of cases are related to preexisting primary synovial chondromatosis (11) (Fig 15). These patients present with pain and swelling, clinical symptoms similar to those accompanying primary synovial chondromatosis. The joints commonly affected with synovial chondrosarcoma are the knee, hip, ankle, and elbow in decreasing order of frequency (87,88). The majority of patients with malignant transformation of primary synovial chondromatosis have long-standing disease with multiple local recurrences. Because local recurrence of primary synovial chondromatosis is not infrequent, distinguishing recurrent disease from malignant transformation can be difficult (11–13,78–86). However, rapid increase in the size of the lesion in a patient with known primary synovial chondromatosis or a rapidly deteriorating clinical course should prompt suspicion of malignant transformation and biopsy of the lesion (11,12,79). Metastases to the lungs are a clear sign of malignancy and unfortunately may represent the clinical feature that is convincing evidence of the diagnosis.

View larger version (57K): [in this window] [in a new window] [Download PPT slide]   Figure 15a.  Malignant transformation of primary synovial chondromatosis to chondrosarcoma involving the foot and ankle in a 24-year-old woman. (a) Anteroposterior radiograph of the foot shows recurrent synovial chondromatosis with multiple calcifications (arrowheads) affecting the mid to hind foot 1 year after the initial resection. Extrinsic erosion of the third metatarsal is also seen (arrow). Lesion was subsequently re-resected. (b, c) Sagittal (b, 500/12) and short-axis (c, 700/12) T1-weighted MR images reveal extensive recurrence of the lesion with multiple areas of marrow invasion and replacement involving the mid and hind foot (*) and low to intermediate signal intensity. (d) Short-axis T2-weighted MR image (7500/120) with fat suppression demonstrates high signal intensity and lobular growth of the lesion (*). (e) Oblique radiograph of the foot obtained 8 months after the MR images shows extensive bone destruction throughout the mid foot and metatarsals (*) with only small areas of calcification (arrowheads). (f, g) Photographs of the gross specimen, coronally sectioned at the mid foot (f) and sagittally sectioned centered at the ankle (g) following below-the-knee amputation, reveal extensive recurrence of synovial chondromatosis (*) with marrow invasion of the talus (ta), tarsal navicular (na), and osseous structures of the mid foot (m). (h) Photomicrograph (original magnification, x125; HE stain) demonstrates histologic features of malignant transformation, with lobules of cartilage (*), binucleate cells (arrowheads), and a more cellular spindled area centrally (circle and inset in right lower corner; original magnification, x350; H-E stain). Different area of this lesion demonstrated decreased cellularity and necrosis (not shown).

View larger version (102K): [in this window] [in a new window] [Download PPT slide]   Figure 15b.  Malignant transformation of primary synovial chondromatosis to chondrosarcoma involving the foot and ankle in a 24-year-old woman. (a) Anteroposterior radiograph of the foot shows recurrent synovial chondromatosis with multiple calcifications (arrowheads) affecting the mid to hind foot 1 year after the initial resection. Extrinsic erosion of the third metatarsal is also seen (arrow). Lesion was subsequently re-resected. (b, c) Sagittal (b, 500/12) and short-axis (c, 700/12) T1-weighted MR images reveal extensive recurrence of the lesion with multiple areas of marrow invasion and replacement involving the mid and hind foot (*) and low to intermediate signal intensity. (d) Short-axis T2-weighted MR image (7500/120) with fat suppression demonstrates high signal intensity and lobular growth of the lesion (*). (e) Oblique radiograph of the foot obtained 8 months after the MR images shows extensive bone destruction throughout the mid foot and metatarsals (*) with only small areas of calcification (arrowheads). (f, g) Photographs of the gross specimen, coronally sectioned at the mid foot (f) and sagittally sectioned centered at the ankle (g) following below-the-knee amputation, reveal extensive recurrence of synovial chondromatosis (*) with marrow invasion of the talus (ta), tarsal navicular (na), and osseous structures of the mid foot (m). (h) Photomicrograph (original magnification, x125; HE stain) demonstrates histologic features of malignant transformation, with lobules of cartilage (*), binucleate cells (arrowheads), and a more cellular spindled area centrally (circle and inset in right lower corner; original magnification, x350; H-E stain). Different area of this lesion demonstrated decreased cellularity and necrosis (not shown).

View larger version (155K): [in this window] [in a new window] [Download PPT slide]   Figure 15c.  Malignant transformation of primary synovial chondromatosis to chondrosarcoma involving the foot and ankle in a 24-year-old woman. (a) Anteroposterior radiograph of the foot shows recurrent synovial chondromatosis with multiple calcifications (arrowheads) affecting the mid to hind foot 1 year after the initial resection. Extrinsic erosion of the third metatarsal is also seen (arrow). Lesion was subsequently re-resected. (b, c) Sagittal (b, 500/12) and short-axis (c, 700/12) T1-weighted MR images reveal extensive recurrence of the lesion with multiple areas of marrow invasion and replacement involving the mid and hind foot (*) and low to intermediate signal intensity. (d) Short-axis T2-weighted MR image (7500/120) with fat suppression demonstrates high signal intensity and lobular growth of the lesion (*). (e) Oblique radiograph of the foot obtained 8 months after the MR images shows extensive bone destruction throughout the mid foot and metatarsals (*) with only small areas of calcification (arrowheads). (f, g) Photographs of the gross specimen, coronally sectioned at the mid foot (f) and sagittally sectioned centered at the ankle (g) following below-the-knee amputation, reveal extensive recurrence of synovial chondromatosis (*) with marrow invasion of the talus (ta), tarsal navicular (na), and osseous structures of the mid foot (m). (h) Photomicrograph (original magnification, x125; HE stain) demonstrates histologic features of malignant transformation, with lobules of cartilage (*), binucleate cells (arrowheads), and a more cellular spindled area centrally (circle and inset in right lower corner; original magnification, x350; H-E stain). Different area of this lesion demonstrated decreased cellularity and necrosis (not shown).

View larger version (154K): [in this window] [in a new window] [Download PPT slide]   Figure 15d.  Malignant transformation of primary synovial chondromatosis to chondrosarcoma involving the foot and ankle in a 24-year-old woman. (a) Anteroposterior radiograph of the foot shows recurrent synovial chondromatosis with multiple calcifications (arrowheads) affecting the mid to hind foot 1 year after the initial resection. Extrinsic erosion of the third metatarsal is also seen (arrow). Lesion was subsequently re-resected. (b, c) Sagittal (b, 500/12) and short-axis (c, 700/12) T1-weighted MR images reveal extensive recurrence of the lesion with multiple areas of marrow invasion and replacement involving the mid and hind foot (*) and low to intermediate signal intensity. (d) Short-axis T2-weighted MR image (7500/120) with fat suppression demonstrates high signal intensity and lobular growth of the lesion (*). (e) Oblique radiograph of the foot obtained 8 months after the MR images shows extensive bone destruction throughout the mid foot and metatarsals (*) with only small areas of calcification (arrowheads). (f, g) Photographs of the gross specimen, coronally sectioned at the mid foot (f) and sagittally sectioned centered at the ankle (g) following below-the-knee amputation, reveal extensive recurrence of synovial chondromatosis (*) with marrow invasion of the talus (ta), tarsal navicular (na), and osseous structures of the mid foot (m). (h) Photomicrograph (original magnification, x125; HE stain) demonstrates histologic features of malignant transformation, with lobules of cartilage (*), binucleate cells (arrowheads), and a more cellular spindled area centrally (circle and inset in right lower corner; original magnification, x350; H-E stain). Different area of this lesion demonstrated decreased cellularity and necrosis (not shown).

View larger version (76K): [in this window] [in a new window] [Download PPT slide]   Figure 15e.  Malignant transformation of primary synovial chondromatosis to chondrosarcoma involving the foot and ankle in a 24-year-old woman. (a) Anteroposterior radiograph of the foot shows recurrent synovial chondromatosis with multiple calcifications (arrowheads) affecting the mid to hind foot 1 year after the initial resection. Extrinsic erosion of the third metatarsal is also seen (arrow). Lesion was subsequently re-resected. (b, c) Sagittal (b, 500/12) and short-axis (c, 700/12) T1-weighted MR images reveal extensive recurrence of the lesion with multiple areas of marrow invasion and replacement involving the mid and hind foot (*) and low to intermediate signal intensity. (d) Short-axis T2-weighted MR image (7500/120) with fat suppression demonstrates high signal intensity and lobular growth of the lesion (*). (e) Oblique radiograph of the foot obtained 8 months after the MR images shows extensive bone destruction throughout the mid foot and metatarsals (*) with only small areas of calcification (arrowheads). (f, g) Photographs of the gross specimen, coronally sectioned at the mid foot (f) and sagittally sectioned centered at the ankle (g) following below-the-knee amputation, reveal extensive recurrence of synovial chondromatosis (*) with marrow invasion of the talus (ta), tarsal navicular (na), and osseous structures of the mid foot (m). (h) Photomicrograph (original magnification, x125; HE stain) demonstrates histologic features of malignant transformation, with lobules of cartilage (*), binucleate cells (arrowheads), and a more cellular spindled area centrally (circle and inset in right lower corner; original magnification, x350; H-E stain). Different area of this lesion demonstrated decreased cellularity and necrosis (not shown).

View larger version (121K): [in this window] [in a new window] [Download PPT slide]   Figure 15f.  Malignant transformation of primary synovial chondromatosis to chondrosarcoma involving the foot and ankle in a 24-year-old woman. (a) Anteroposterior radiograph of the foot shows recurrent synovial chondromatosis with multiple calcifications (arrowheads) affecting the mid to hind foot 1 year after the initial resection. Extrinsic erosion of the third metatarsal is also seen (arrow). Lesion was subsequently re-resected. (b, c) Sagittal (b, 500/12) and short-axis (c, 700/12) T1-weighted MR images reveal extensive recurrence of the lesion with multiple areas of marrow invasion and replacement involving the mid and hind foot (*) and low to intermediate signal intensity. (d) Short-axis T2-weighted MR image (7500/120) with fat suppression demonstrates high signal intensity and lobular growth of the lesion (*). (e) Oblique radiograph of the foot obtained 8 months after the MR images shows extensive bone destruction throughout the mid foot and metatarsals (*) with only small areas of calcification (arrowheads). (f, g) Photographs of the gross specimen, coronally sectioned at the mid foot (f) and sagittally sectioned centered at the ankle (g) following below-the-knee amputation, reveal extensive recurrence of synovial chondromatosis (*) with marrow invasion of the talus (ta), tarsal navicular (na), and osseous structures of the mid foot (m). (h) Photomicrograph (original magnification, x125; HE stain) demonstrates histologic features of malignant transformation, with lobules of cartilage (*), binucleate cells (arrowheads), and a more cellular spindled area centrally (circle and inset in right lower corner; original magnification, x350; H-E stain). Different area of this lesion demonstrated decreased cellularity and necrosis (not shown).

View larger version (120K): [in this window] [in a new window] [Download PPT slide]   Figure 15g.  Malignant transformation of primary synovial chondromatosis to chondrosarcoma involving the foot and ankle in a 24-year-old woman. (a) Anteroposterior radiograph of the foot shows recurrent synovial chondromatosis with multiple calcifications (arrowheads) affecting the mid to hind foot 1 year after the initial resection. Extrinsic erosion of the third metatarsal is also seen (arrow). Lesion was subsequently re-resected. (b, c) Sagittal (b, 500/12) and short-axis (c, 700/12) T1-weighted MR images reveal extensive recurrence of the lesion with multiple areas of marrow invasion and replacement involving the mid and hind foot (*) and low to intermediate signal intensity. (d) Short-axis T2-weighted MR image (7500/120) with fat suppression demonstrates high signal intensity and lobular growth of the lesion (*). (e) Oblique radiograph of the foot obtained 8 months after the MR images shows extensive bone destruction throughout the mid foot and metatarsals (*) with only small areas of calcification (arrowheads). (f, g) Photographs of the gross specimen, coronally sectioned at the mid foot (f) and sagittally sectioned centered at the ankle (g) following below-the-knee amputation, reveal extensive recurrence of synovial chondromatosis (*) with marrow invasion of the talus (ta), tarsal navicular (na), and osseous structures of the mid foot (m). (h) Photomicrograph (original magnification, x125; HE stain) demonstrates histologic features of malignant transformation, with lobules of cartilage (*), binucleate cells (arrowheads), and a more cellular spindled area centrally (circle and inset in right lower corner; original magnification, x350; H-E stain). Different area of this lesion demonstrated decreased cellularity and necrosis (not shown).

View larger version (165K): [in this window] [in a new window] [Download PPT slide]   Figure 15h.  Malignant transformation of primary synovial chondromatosis to chondrosarcoma involving the foot and ankle in a 24-year-old woman. (a) Anteroposterior radiograph of the foot shows recurrent synovial chondromatosis with multiple calcifications (arrowheads) affecting the mid to hind foot 1 year after the initial resection. Extrinsic erosion of the third metatarsal is also seen (arrow). Lesion was subsequently re-resected. (b, c) Sagittal (b, 500/12) and short-axis (c, 700/12) T1-weighted MR images reveal extensive recurrence of the lesion with multiple areas of marrow invasion and replacement involving the mid and hind foot (*) and low to intermediate signal intensity. (d) Short-axis T2-weighted MR image (7500/120) with fat suppression demonstrates high signal intensity and lobular growth of the lesion (*). (e) Oblique radiograph of the foot obtained 8 months after the MR images shows extensive bone destruction throughout the mid foot and metatarsals (*) with only small areas of calcification (arrowheads). (f, g) Photographs of the gross specimen, coronally sectioned at the mid foot (f) and sagittally sectioned centered at the ankle (g) following below-the-knee amputation, reveal extensive recurrence of synovial chondromatosis (*) with marrow invasion of the talus (ta), tarsal navicular (na), and osseous structures of the mid foot (m). (h) Photomicrograph (original magnification, x125; HE stain) demonstrates histologic features of malignant transformation, with lobules of cartilage (*), binucleate cells (arrowheads), and a more cellular spindled area centrally (circle and inset in right lower corner; original magnification, x350; H-E stain). Different area of this lesion demonstrated decreased cellularity and necrosis (not shown).

Recurrent primary synovial chondromatosis and malignant transformation to chondrosarcoma may have radiologically similar appearances, with an extensive calcified soft-tissue mass about and within the joint. Extension into the adjacent soft tissues (particularly into bursae) may be seen both with and without malignant transformation and is therefore not an adequate distinguishing imaging feature (11,13,78,87). Similarly, extrinsic erosion of bone, which can be quite deep and suggestive of a more aggressive process, may be seen in both conditions. However, in our experience and in agreement with Bertoni and colleagues (11), true cortical destruction with bone marrow invasion and permeation is a feature that should be considered a sign of malignancy (Fig 15). Because of its superior contrast resolution (particularly with T1-weighted pulse sequences), MR imaging is optimal for detecting true marrow invasion and for differentiating this feature from deep extrinsic erosion. Periosteal reaction may also be seen associated with the bone destruction (86).

Treatment of patients with malignant transformation of primary synovial chondromatosis usually requires amputation. Despite this aggressive therapy, metastases to the lung are common and were reported in 56% of patients with follow-up in the series of Bertoni et al (11). Patient death was reported in 44% and 67% of patients in the studies of Bertoni et al (11) and Davis et al (12), respectively. As with other chondrosarcomas, synovial chondrosarcoma is typically not effectively treated with chemotherapy and radiation therapy, and these methods are not employed as adjunct treatment.

	Summary

Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Clinical Characteristics Pathologic Features Imaging Features Treatment and Prognosis Malignant Transformation of... Summary References

 
Primary synovial chondromatosis represents an uncommon benign neoplastic process in which hyaline cartilage nodules form in subsynovial tissue of the joint, tendon sheath, or bursa. These nodules may subsequently enlarge and detach to lie within the joint space. We have reviewed, illustrated, and correlated the clinical, pathologic, and radiologic features of primary synovial chondromatosis and discussed its treatment and prognosis. Primary synovial chondromatosis most frequently affects the knee in men, followed by the hip. The radiologic appearance of primary synovial chondromatosis is frequently pathognomonic. Radiography demonstrates innumerable calcified intraarticular chondral bodies of similar size and shape. CT is the optimal imaging modality to detect and characterize the calcified intraarticular bodies, particularly in complex areas of anatomy such as the hip. MR imaging demonstrates variable intrinsic appearances, depending on the degree of calcification, although the extent of disease (particularly soft-tissue or bursal involvement) is optimally depicted. Secondary synovial chondromatosis can be distinguished from primary disease both pathologically and radiologically by its association with underlying joint abnormality (typically osteoarthritis), fewer chondral bodies of variable size and shape, and concentric rings of growth. Treatment of choice for primary synovial chondromatosis is surgical synovectomy with removal of chondral fragments. Malignant transformation of primary synovial chondromatosis to chondrosarcoma is unusual and can be difficult to distinguish from benign disease, both pathologically and radiologically. However, multiple recurrences with development of marrow invasion should be viewed as representing malignant transformation. Understanding and recognizing the spectrum of radiologic appearances and their pathologic basis allow improved patient assessment and are important to optimize clinical management.

	Acknowledgments

 
The authors gratefully acknowledge the support of Janice Danqing Liu and Anika Torruella for manuscript preparation and the residents who attend the radiologic pathology courses (past, present, and future) of the Armed Forces Institute of Pathology for their contributions to our series of patients. Without them, this project would not have been possible.

	Footnotes

 

Abbreviations: H-E = hematoxylin-eosin, TR = repetition time

The opinions or assertions contained herein are the private views of the authors and are not to be construed as official nor as reflecting the views of the Departments of the Army, Navy, or Defense.

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Top Abstract LEARNING OBJECTIVES FOR TEST... Introduction Clinical Characteristics Pathologic Features Imaging Features Treatment and Prognosis Malignant Transformation of... Summary References

 

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