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Imaging Findings in Musculoskeletal Complications of AIDS¹

¹ From the Department of Radiology, Louisiana State University Health Sciences Center, 1542 Tulane Ave, Rm 212, New Orleans, LA 70112. Presented as an education exhibit at the 2002 RSNA scientific assembly. Received June 17, 2003; revision requested July 17 and final revision received January 16, 2004; accepted January 16. All authors have no financial relationships to disclose. Address correspondence to C.S.R. (e-mail: crestr@lsuhsc.edu).

View larger version (130K): [in a new window]   Figure 1.  Superficial and deep cellulitis and myositis in a 42-year-old man. Axial CT scan obtained at the level of the middle third of the leg shows inflammatory changes in the subcutaneous soft tissues, with fluid collections surrounding the intramuscular compartments in the lateral aspect of the leg adjacent to the tibialis anterior muscle and in the medial compartment adjacent to the soleus muscle (solid arrows). Inflammatory changes consistent with myositis are also seen within the soleus muscle (open arrow).

View larger version (118K): [in a new window]   Figure 2a.  Necrotizing fasciitis in a 45-year-old male intravenous drug abuser. Coronal (a) and axial (b) fat-suppressed T2-weighted MR images show high-signal-intensity inflammatory changes involving both the subcutaneous fat in the medial surface (arrow in a) and the gastrocnemius and soleus muscles (arrows in b) of the left leg. This hyperintensity is consistent with deep-seated infection or necrotizing fasciitis.

View larger version (87K): [in a new window]   Figure 2b.  Necrotizing fasciitis in a 45-year-old male intravenous drug abuser. Coronal (a) and axial (b) fat-suppressed T2-weighted MR images show high-signal-intensity inflammatory changes involving both the subcutaneous fat in the medial surface (arrow in a) and the gastrocnemius and soleus muscles (arrows in b) of the left leg. This hyperintensity is consistent with deep-seated infection or necrotizing fasciitis.

View larger version (97K): [in a new window]   Figure 3a.  Soft-tissue abscess in a 21-year-old man with a history of intravenous drug abuse. Axial unenhanced (a) and contrast-enhanced (b) fat-suppressed T1-weighted MR images of the hand show extensive inflammatory changes and abscess formation within the muscles and soft tissues of the thenar and palmar region. An abscess is seen within the first dorsal interosseous and adductor pollicis muscles (arrow). This fluid collection has low signal intensity on the unenhanced image and peripheral ring enhancement with central low signal intensity on the contrast-enhanced image. The absence of tendon sheath and bursal involvement helped rule out the presence of horseshoe abscess formation.

View larger version (104K): [in a new window]   Figure 3b.  Soft-tissue abscess in a 21-year-old man with a history of intravenous drug abuse. Axial unenhanced (a) and contrast-enhanced (b) fat-suppressed T1-weighted MR images of the hand show extensive inflammatory changes and abscess formation within the muscles and soft tissues of the thenar and palmar region. An abscess is seen within the first dorsal interosseous and adductor pollicis muscles (arrow). This fluid collection has low signal intensity on the unenhanced image and peripheral ring enhancement with central low signal intensity on the contrast-enhanced image. The absence of tendon sheath and bursal involvement helped rule out the presence of horseshoe abscess formation.

View larger version (97K): [in a new window]   Figure 4.  Pyomyositis in a 25-year-old woman. Axial contrast-enhanced CT scan of the lower neck demonstrates multiple abscesses in the soft tissues and muscles of the supraclavicular space and neck (arrows). Results of aspiration confirmed M tuberculosis myositis and lymph node involvement.

View larger version (90K): [in a new window]   Figure 5a.  Pyomyositis in a 35-year-old man. (a) Axial contrast-enhanced fat-suppressed T1-weighted MR image demonstrates extensive inflammatory changes involving the deep muscles of the right midthigh, with enhancement within the vastus intermedius muscle that extends into the adductor muscles (arrows). Note the increased diameter of the right thigh compared with the left thigh. (b) On an axial fat-suppressed T2-weighted MR image, there is extensive cellulitis of the superficial and deep compartments with diffuse myositis of almost all the right-sided muscles, with less diffuse involvement of the left thigh. Note also the bilateral fluid collections superficial to the vastus lateralis muscles (arrows).

View larger version (94K): [in a new window]   Figure 5b.  Pyomyositis in a 35-year-old man. (a) Axial contrast-enhanced fat-suppressed T1-weighted MR image demonstrates extensive inflammatory changes involving the deep muscles of the right midthigh, with enhancement within the vastus intermedius muscle that extends into the adductor muscles (arrows). Note the increased diameter of the right thigh compared with the left thigh. (b) On an axial fat-suppressed T2-weighted MR image, there is extensive cellulitis of the superficial and deep compartments with diffuse myositis of almost all the right-sided muscles, with less diffuse involvement of the left thigh. Note also the bilateral fluid collections superficial to the vastus lateralis muscles (arrows).

View larger version (162K): [in a new window]   Figure 6a.  Pyomyositis with myonecrosis in a 38-year-old man. (a) Coronal T1-weighted MR image shows extensive myonecrosis affecting the medial compartments of the lower extremities, with bilateral hypointense fluid collections (arrows). (b) On a coronal fat-suppressed T2-weighted MR image, the bilateral fluid collections demonstrate high signal intensity. The multiple round, ill-defined low-signal-intensity areas within the necrotic collection on the left side (arrows) represent abnormal gas bubbles. (c) Axial contrast-enhanced fat-suppressed T1-weighted MR image shows intense peripheral rim enhancement surrounding the bilateral fluid collections (arrows) and the gas bubbles within the necrotic tissue on the left side.

View larger version (149K): [in a new window]   Figure 6b.  Pyomyositis with myonecrosis in a 38-year-old man. (a) Coronal T1-weighted MR image shows extensive myonecrosis affecting the medial compartments of the lower extremities, with bilateral hypointense fluid collections (arrows). (b) On a coronal fat-suppressed T2-weighted MR image, the bilateral fluid collections demonstrate high signal intensity. The multiple round, ill-defined low-signal-intensity areas within the necrotic collection on the left side (arrows) represent abnormal gas bubbles. (c) Axial contrast-enhanced fat-suppressed T1-weighted MR image shows intense peripheral rim enhancement surrounding the bilateral fluid collections (arrows) and the gas bubbles within the necrotic tissue on the left side.

View larger version (60K): [in a new window]   Figure 6c.  Pyomyositis with myonecrosis in a 38-year-old man. (a) Coronal T1-weighted MR image shows extensive myonecrosis affecting the medial compartments of the lower extremities, with bilateral hypointense fluid collections (arrows). (b) On a coronal fat-suppressed T2-weighted MR image, the bilateral fluid collections demonstrate high signal intensity. The multiple round, ill-defined low-signal-intensity areas within the necrotic collection on the left side (arrows) represent abnormal gas bubbles. (c) Axial contrast-enhanced fat-suppressed T1-weighted MR image shows intense peripheral rim enhancement surrounding the bilateral fluid collections (arrows) and the gas bubbles within the necrotic tissue on the left side.

View larger version (90K): [in a new window]   Figure 7.  Pyomyositis in a 23-year-old man with AIDS and a history of intravenous drug abuse. Radiograph demonstrates multiple gas collections (arrows) within the soft tissues of the medial and posterior left thigh.

View larger version (96K): [in a new window]   Figure 8a.  Chronic osteomyelitis in a 41-year-old man. Anteroposterior (a) and lateral (b) radiographs show extensive soft-tissue ulceration of the distal forearm associated with periosteal reaction of the distal ulna and, to a lesser extent, of the distal radius projecting into the interosseous space. Results of pathologic analysis proved extensive necrotic changes, but no definitive bacteria or infectious agent could be identified.

View larger version (63K): [in a new window]   Figure 8b.  Chronic osteomyelitis in a 41-year-old man. Anteroposterior (a) and lateral (b) radiographs show extensive soft-tissue ulceration of the distal forearm associated with periosteal reaction of the distal ulna and, to a lesser extent, of the distal radius projecting into the interosseous space. Results of pathologic analysis proved extensive necrotic changes, but no definitive bacteria or infectious agent could be identified.

View larger version (121K): [in a new window]   Figure 9.  Osteomyelitis in a 41-year-old woman. Coronal contrast-enhanced fat-suppressed T1-weighted MR image demonstrates osteomyelitis of the right wing of the sacrum and septic arthritis of the right sacroiliac joint. Abscesses with peripheral rim enhancement are seen within the right iliac and gluteal muscles and the sacrum. Aspiration and culture demonstrated M tuberculosis infection.

View larger version (150K): [in a new window]   Figure 10.  Osteomyelitis and septic sacroiliitis in a 46-year-old female intravenous drug abuser with septic endocarditis. Axial T1-weighted MR image demonstrates a hypointense lesion in the right sacroiliac joint (arrow) with extension into the right iliac bone and sacrum. Pathologic analysis demonstrated S pyogenes.

View larger version (187K): [in a new window]   Figure 11a.  Acute spondylodiskitis and vertebral osteomyelitis in a 46-year-old woman. (a) Sagittal T1-weighted MR image shows acute spondylodiskitis and vertebral osteomyelitis with epidural collections (open arrow) and dural enhancement (solid arrows) at the C5-C6 level. These inflammatory findings are nonspecific and can be observed in a variety of granulomatous, fungal, and bacterial infections. One week later, the patient developed extensive wedge deformity and collapse of C5 and C6. (b) Axial contrast-enhanced T1-weighted MR image demonstrates abnormal dural enhancement and cord compression secondary to the epidural fluid collections (arrows).

View larger version (118K): [in a new window]   Figure 11b.  Acute spondylodiskitis and vertebral osteomyelitis in a 46-year-old woman. (a) Sagittal T1-weighted MR image shows acute spondylodiskitis and vertebral osteomyelitis with epidural collections (open arrow) and dural enhancement (solid arrows) at the C5-C6 level. These inflammatory findings are nonspecific and can be observed in a variety of granulomatous, fungal, and bacterial infections. One week later, the patient developed extensive wedge deformity and collapse of C5 and C6. (b) Axial contrast-enhanced T1-weighted MR image demonstrates abnormal dural enhancement and cord compression secondary to the epidural fluid collections (arrows).

View larger version (114K): [in a new window]   Figure 12a.  Septic arthritis and bursitis in a 42-year-old woman. (a) Coronal fat-suppressed T2-weighted MR image shows extensive fluid collections within the bursae around the shoulder, especially the subacromial (subdeltoid) bursa (arrows). (b) On a sagittal contrast-enhanced fat-suppressed T1-weighted MR image, the fluid collections (arrows) exhibit low signal intensity with no enhancement.

View larger version (124K): [in a new window]   Figure 12b.  Septic arthritis and bursitis in a 42-year-old woman. (a) Coronal fat-suppressed T2-weighted MR image shows extensive fluid collections within the bursae around the shoulder, especially the subacromial (subdeltoid) bursa (arrows). (b) On a sagittal contrast-enhanced fat-suppressed T1-weighted MR image, the fluid collections (arrows) exhibit low signal intensity with no enhancement.

View larger version (144K): [in a new window]   Figure 13a.  NHL in a 40-year-old man. (a) Radiograph of the pelvis shows an ill-defined lytic lesion in the right iliac bone (arrows). (b) Axial contrast-enhanced CT scan helps confirm the lytic lesion, demonstrating cortical disruption of the iliac bone (solid arrows) with an associated enhancing soft-tissue mass involving the right iliacus muscle (open arrow).

View larger version (97K): [in a new window]   Figure 13b.  NHL in a 40-year-old man. (a) Radiograph of the pelvis shows an ill-defined lytic lesion in the right iliac bone (arrows). (b) Axial contrast-enhanced CT scan helps confirm the lytic lesion, demonstrating cortical disruption of the iliac bone (solid arrows) with an associated enhancing soft-tissue mass involving the right iliacus muscle (open arrow).

View larger version (136K): [in a new window]   Figure 14a.  Multicentric B-cell NHL in a 44-year-old man. (a) Anteroposterior chest radiograph shows multiple osteolytic lesions (arrows) involving the right humerus, the right and left scapulae, the medial third of the right clavicle, and multiple left ribs. (b) Follow-up chest radiograph obtained 3 months later demonstrates progression of the disease, with diffuse lymphomatous involvement of both lungs and more prominent multiple osteolytic lesions (arrows). (c) Sagittal T1-weighted brain MR image shows a soft-tissue tumor with both extradural involvement (solid arrow) and subgaleal extension (open arrow) within the medullary cavity of the parietal bone. (d) On an axial T2-weighted MR image, the soft-tissue mass has intermediate signal intensity due to bone involvement and extends to the subgaleal space (solid arrow). Abnormal signal intensity owing to tumor involvement is also seen within the left parietal bone (open arrow). (e) Anteroposterior radiograph of the right knee shows a destructive osteolytic lesion of the proximal lateral tibial metaphysis (arrow). (f) Sagittal T1-weighted MR image shows the infiltrative tumor that is isointense relative to muscle and replaces the bone marrow of the proximal tibia (arrow). Flexion deformity of the knee secondary to pain is also appreciated. (g) Tc-99m bone scintigram (left) with magnified view (right) show extensive abnormal radiotracer uptake at the level of the distal femur and proximal tibia (solid arrows) and in the skull (open arrow). There is also abnormal uptake in the proximal femoral shaft (arrowheads).

View larger version (117K): [in a new window]   Figure 14b.  Multicentric B-cell NHL in a 44-year-old man. (a) Anteroposterior chest radiograph shows multiple osteolytic lesions (arrows) involving the right humerus, the right and left scapulae, the medial third of the right clavicle, and multiple left ribs. (b) Follow-up chest radiograph obtained 3 months later demonstrates progression of the disease, with diffuse lymphomatous involvement of both lungs and more prominent multiple osteolytic lesions (arrows). (c) Sagittal T1-weighted brain MR image shows a soft-tissue tumor with both extradural involvement (solid arrow) and subgaleal extension (open arrow) within the medullary cavity of the parietal bone. (d) On an axial T2-weighted MR image, the soft-tissue mass has intermediate signal intensity due to bone involvement and extends to the subgaleal space (solid arrow). Abnormal signal intensity owing to tumor involvement is also seen within the left parietal bone (open arrow). (e) Anteroposterior radiograph of the right knee shows a destructive osteolytic lesion of the proximal lateral tibial metaphysis (arrow). (f) Sagittal T1-weighted MR image shows the infiltrative tumor that is isointense relative to muscle and replaces the bone marrow of the proximal tibia (arrow). Flexion deformity of the knee secondary to pain is also appreciated. (g) Tc-99m bone scintigram (left) with magnified view (right) show extensive abnormal radiotracer uptake at the level of the distal femur and proximal tibia (solid arrows) and in the skull (open arrow). There is also abnormal uptake in the proximal femoral shaft (arrowheads).

View larger version (159K): [in a new window]   Figure 14c.  Multicentric B-cell NHL in a 44-year-old man. (a) Anteroposterior chest radiograph shows multiple osteolytic lesions (arrows) involving the right humerus, the right and left scapulae, the medial third of the right clavicle, and multiple left ribs. (b) Follow-up chest radiograph obtained 3 months later demonstrates progression of the disease, with diffuse lymphomatous involvement of both lungs and more prominent multiple osteolytic lesions (arrows). (c) Sagittal T1-weighted brain MR image shows a soft-tissue tumor with both extradural involvement (solid arrow) and subgaleal extension (open arrow) within the medullary cavity of the parietal bone. (d) On an axial T2-weighted MR image, the soft-tissue mass has intermediate signal intensity due to bone involvement and extends to the subgaleal space (solid arrow). Abnormal signal intensity owing to tumor involvement is also seen within the left parietal bone (open arrow). (e) Anteroposterior radiograph of the right knee shows a destructive osteolytic lesion of the proximal lateral tibial metaphysis (arrow). (f) Sagittal T1-weighted MR image shows the infiltrative tumor that is isointense relative to muscle and replaces the bone marrow of the proximal tibia (arrow). Flexion deformity of the knee secondary to pain is also appreciated. (g) Tc-99m bone scintigram (left) with magnified view (right) show extensive abnormal radiotracer uptake at the level of the distal femur and proximal tibia (solid arrows) and in the skull (open arrow). There is also abnormal uptake in the proximal femoral shaft (arrowheads).

View larger version (151K): [in a new window]   Figure 14d.  Multicentric B-cell NHL in a 44-year-old man. (a) Anteroposterior chest radiograph shows multiple osteolytic lesions (arrows) involving the right humerus, the right and left scapulae, the medial third of the right clavicle, and multiple left ribs. (b) Follow-up chest radiograph obtained 3 months later demonstrates progression of the disease, with diffuse lymphomatous involvement of both lungs and more prominent multiple osteolytic lesions (arrows). (c) Sagittal T1-weighted brain MR image shows a soft-tissue tumor with both extradural involvement (solid arrow) and subgaleal extension (open arrow) within the medullary cavity of the parietal bone. (d) On an axial T2-weighted MR image, the soft-tissue mass has intermediate signal intensity due to bone involvement and extends to the subgaleal space (solid arrow). Abnormal signal intensity owing to tumor involvement is also seen within the left parietal bone (open arrow). (e) Anteroposterior radiograph of the right knee shows a destructive osteolytic lesion of the proximal lateral tibial metaphysis (arrow). (f) Sagittal T1-weighted MR image shows the infiltrative tumor that is isointense relative to muscle and replaces the bone marrow of the proximal tibia (arrow). Flexion deformity of the knee secondary to pain is also appreciated. (g) Tc-99m bone scintigram (left) with magnified view (right) show extensive abnormal radiotracer uptake at the level of the distal femur and proximal tibia (solid arrows) and in the skull (open arrow). There is also abnormal uptake in the proximal femoral shaft (arrowheads).

View larger version (88K): [in a new window]   Figure 14e.  Multicentric B-cell NHL in a 44-year-old man. (a) Anteroposterior chest radiograph shows multiple osteolytic lesions (arrows) involving the right humerus, the right and left scapulae, the medial third of the right clavicle, and multiple left ribs. (b) Follow-up chest radiograph obtained 3 months later demonstrates progression of the disease, with diffuse lymphomatous involvement of both lungs and more prominent multiple osteolytic lesions (arrows). (c) Sagittal T1-weighted brain MR image shows a soft-tissue tumor with both extradural involvement (solid arrow) and subgaleal extension (open arrow) within the medullary cavity of the parietal bone. (d) On an axial T2-weighted MR image, the soft-tissue mass has intermediate signal intensity due to bone involvement and extends to the subgaleal space (solid arrow). Abnormal signal intensity owing to tumor involvement is also seen within the left parietal bone (open arrow). (e) Anteroposterior radiograph of the right knee shows a destructive osteolytic lesion of the proximal lateral tibial metaphysis (arrow). (f) Sagittal T1-weighted MR image shows the infiltrative tumor that is isointense relative to muscle and replaces the bone marrow of the proximal tibia (arrow). Flexion deformity of the knee secondary to pain is also appreciated. (g) Tc-99m bone scintigram (left) with magnified view (right) show extensive abnormal radiotracer uptake at the level of the distal femur and proximal tibia (solid arrows) and in the skull (open arrow). There is also abnormal uptake in the proximal femoral shaft (arrowheads).

View larger version (84K): [in a new window]   Figure 14f.  Multicentric B-cell NHL in a 44-year-old man. (a) Anteroposterior chest radiograph shows multiple osteolytic lesions (arrows) involving the right humerus, the right and left scapulae, the medial third of the right clavicle, and multiple left ribs. (b) Follow-up chest radiograph obtained 3 months later demonstrates progression of the disease, with diffuse lymphomatous involvement of both lungs and more prominent multiple osteolytic lesions (arrows). (c) Sagittal T1-weighted brain MR image shows a soft-tissue tumor with both extradural involvement (solid arrow) and subgaleal extension (open arrow) within the medullary cavity of the parietal bone. (d) On an axial T2-weighted MR image, the soft-tissue mass has intermediate signal intensity due to bone involvement and extends to the subgaleal space (solid arrow). Abnormal signal intensity owing to tumor involvement is also seen within the left parietal bone (open arrow). (e) Anteroposterior radiograph of the right knee shows a destructive osteolytic lesion of the proximal lateral tibial metaphysis (arrow). (f) Sagittal T1-weighted MR image shows the infiltrative tumor that is isointense relative to muscle and replaces the bone marrow of the proximal tibia (arrow). Flexion deformity of the knee secondary to pain is also appreciated. (g) Tc-99m bone scintigram (left) with magnified view (right) show extensive abnormal radiotracer uptake at the level of the distal femur and proximal tibia (solid arrows) and in the skull (open arrow). There is also abnormal uptake in the proximal femoral shaft (arrowheads).

View larger version (104K): [in a new window]   Figure 14g.  Multicentric B-cell NHL in a 44-year-old man. (a) Anteroposterior chest radiograph shows multiple osteolytic lesions (arrows) involving the right humerus, the right and left scapulae, the medial third of the right clavicle, and multiple left ribs. (b) Follow-up chest radiograph obtained 3 months later demonstrates progression of the disease, with diffuse lymphomatous involvement of both lungs and more prominent multiple osteolytic lesions (arrows). (c) Sagittal T1-weighted brain MR image shows a soft-tissue tumor with both extradural involvement (solid arrow) and subgaleal extension (open arrow) within the medullary cavity of the parietal bone. (d) On an axial T2-weighted MR image, the soft-tissue mass has intermediate signal intensity due to bone involvement and extends to the subgaleal space (solid arrow). Abnormal signal intensity owing to tumor involvement is also seen within the left parietal bone (open arrow). (e) Anteroposterior radiograph of the right knee shows a destructive osteolytic lesion of the proximal lateral tibial metaphysis (arrow). (f) Sagittal T1-weighted MR image shows the infiltrative tumor that is isointense relative to muscle and replaces the bone marrow of the proximal tibia (arrow). Flexion deformity of the knee secondary to pain is also appreciated. (g) Tc-99m bone scintigram (left) with magnified view (right) show extensive abnormal radiotracer uptake at the level of the distal femur and proximal tibia (solid arrows) and in the skull (open arrow). There is also abnormal uptake in the proximal femoral shaft (arrowheads).

View larger version (163K): [in a new window]   Figure 15a.  Multicentric lymphoma with involvement of the craniofacial region in a 31-year-old patient. (a) Axial CT scan obtained at the level of the midface shows a prominent soft-tissue mass that occupies the left maxillary region and extends into the soft tissues of the face. Aggressive bone destruction of the anterior and medial walls of the left antrum is also seen (arrows). (b) Axial CT scan of the superior head shows multiple round, hypoattenuating lytic lesions of the calvaria (arrowheads). (c) Sagittal T1-weighted MR image demonstrates a prominent mass that infiltrates the superficial and deep structures of the face (arrow). The multiple osteolytic lesions within the marrow of the cranial bones have moderate signal intensity (arrowheads), in contrast with the low signal intensity of the normal bone. (d) Axial contrast-enhanced T1-weighted MR image shows multiple enhancing hyperintense soft-tissue masses within the medullary cavity of the bones of the skull vault (arrowheads). Some of the masses extend into the epidural space.

View larger version (118K): [in a new window]   Figure 15b.  Multicentric lymphoma with involvement of the craniofacial region in a 31-year-old patient. (a) Axial CT scan obtained at the level of the midface shows a prominent soft-tissue mass that occupies the left maxillary region and extends into the soft tissues of the face. Aggressive bone destruction of the anterior and medial walls of the left antrum is also seen (arrows). (b) Axial CT scan of the superior head shows multiple round, hypoattenuating lytic lesions of the calvaria (arrowheads). (c) Sagittal T1-weighted MR image demonstrates a prominent mass that infiltrates the superficial and deep structures of the face (arrow). The multiple osteolytic lesions within the marrow of the cranial bones have moderate signal intensity (arrowheads), in contrast with the low signal intensity of the normal bone. (d) Axial contrast-enhanced T1-weighted MR image shows multiple enhancing hyperintense soft-tissue masses within the medullary cavity of the bones of the skull vault (arrowheads). Some of the masses extend into the epidural space.

View larger version (142K): [in a new window]   Figure 15c.  Multicentric lymphoma with involvement of the craniofacial region in a 31-year-old patient. (a) Axial CT scan obtained at the level of the midface shows a prominent soft-tissue mass that occupies the left maxillary region and extends into the soft tissues of the face. Aggressive bone destruction of the anterior and medial walls of the left antrum is also seen (arrows). (b) Axial CT scan of the superior head shows multiple round, hypoattenuating lytic lesions of the calvaria (arrowheads). (c) Sagittal T1-weighted MR image demonstrates a prominent mass that infiltrates the superficial and deep structures of the face (arrow). The multiple osteolytic lesions within the marrow of the cranial bones have moderate signal intensity (arrowheads), in contrast with the low signal intensity of the normal bone. (d) Axial contrast-enhanced T1-weighted MR image shows multiple enhancing hyperintense soft-tissue masses within the medullary cavity of the bones of the skull vault (arrowheads). Some of the masses extend into the epidural space.

View larger version (151K): [in a new window]   Figure 15d.  Multicentric lymphoma with involvement of the craniofacial region in a 31-year-old patient. (a) Axial CT scan obtained at the level of the midface shows a prominent soft-tissue mass that occupies the left maxillary region and extends into the soft tissues of the face. Aggressive bone destruction of the anterior and medial walls of the left antrum is also seen (arrows). (b) Axial CT scan of the superior head shows multiple round, hypoattenuating lytic lesions of the calvaria (arrowheads). (c) Sagittal T1-weighted MR image demonstrates a prominent mass that infiltrates the superficial and deep structures of the face (arrow). The multiple osteolytic lesions within the marrow of the cranial bones have moderate signal intensity (arrowheads), in contrast with the low signal intensity of the normal bone. (d) Axial contrast-enhanced T1-weighted MR image shows multiple enhancing hyperintense soft-tissue masses within the medullary cavity of the bones of the skull vault (arrowheads). Some of the masses extend into the epidural space.

View larger version (98K): [in a new window]   Figure 16.  Kaposi sarcoma with cutaneous, muscular, and osseous involvement in a 25-year-old man. Axial contrast-enhanced CT scan of the lower chest shows multiple round, enhancing lesions in the muscles of the chest wall (arrowheads). Bone involvement is seen in one of the posterior left ribs (arrow).

View larger version (142K): [in a new window]   Figure 17a.  Avascular necrosis (AVN) in a 49-year-old man who presented with right hip pain. (a) Initial anteroposterior radiograph of the pelvis demonstrates ill-defined areas of irregular increased opacity in the right femoral head. (b) Anteroposterior radiograph obtained 3 months later reveals extensive erosion and collapse of the right femoral head secondary to AVN, with cephalic and lateral displacement of the femur.

View larger version (133K): [in a new window]   Figure 17b.  Avascular necrosis (AVN) in a 49-year-old man who presented with right hip pain. (a) Initial anteroposterior radiograph of the pelvis demonstrates ill-defined areas of irregular increased opacity in the right femoral head. (b) Anteroposterior radiograph obtained 3 months later reveals extensive erosion and collapse of the right femoral head secondary to AVN, with cephalic and lateral displacement of the femur.

View larger version (121K): [in a new window]   Figure 18.   AVN. Anteroposterior radiographs of the ankles show intramedullary bone infarcts at the distal tibial diaphyses as irregular calcifications with the long axes parallel to the cortical bones (arrow).

View larger version (147K): [in a new window]   Figure 19.  AVN in an HIV-positive patient. Anteroposterior (left) and lateral (right) radiographs of the right knee show multiple intramedullary bone infarcts of the femur and tibia (arrows).

View larger version (106K): [in a new window]   Figure 20.  Rhabdomyolysis in a 44-year-old man with AIDS and renal failure. Axial unenhanced CT scan of the abdomen demonstrates bilateral abnormal increased attenuation of the psoas muscle (arrows) and, to a lesser extent, of the paraspinal and oblique abdominal muscles (arrowheads) due to diffuse calcifications.

View larger version (135K): [in a new window]   Figure 21.  Hypertrophic osteoarthropathy in a 35-year-old man with AIDS and P carinii pneumonia. Anteroposterior (left) and lateral (right) radiographs of the right knee show abnormal thickening of the cortical bone with diffuse periosteal bone formation at the distal femur and proximal tibia (arrowheads). The changes were seen bilaterally.