DOI: 10.1148/rg.233025165
(Radiographics. 2003;23:759-783.)
© RSNA, 2003
From the Archives of the AFIP
Localized Fibrous Tumors of the Pleura1
Melissa L. Rosado-de-Christenson, MD,
Gerald F. Abbott, MD,
H. Page McAdams, MD,
Teri J. Franks, MD and
Jeffrey R. Galvin, MD
1 From the Department of Radiology and Nuclear Medicine, Uniformed Services University of the Health Sciences, Bethesda, Md (M.L.R.); Department of Diagnostic Imaging, Brown Medical School, Rhode Island Hospital, Providence, RI (G.F.A.); Department of Radiology, Duke University Medical Center, Durham, NC (H.P.M.); and Departments of Pulmonary and Mediastinal Pathology (T.J.F.) and Radiologic Pathology (J.R.G.), Armed Forces Institute of Pathology, Washington, DC. Received November 19, 2002; revision requested January 13, 2003 and received February 10; accepted February 13. Address correspondence to M.L.R., 7948 Creek Hollow Rd, Blacklick, OH 43004 (e-mail: rosado@insight.rr.com).
 |
Abstract
|
|---|
Eighty-two localized fibrous tumors of the pleura (LFTP) were reviewed retrospectively for the clinical, pathologic, and radiologic findings. Forty-four women and 38 men ranged in age from 17 to 78 years (mean, 54.7 years). Sixty-four benign LFTP ranged in size from 2 to 30 cm (mean, 13.2 cm), and 18 malignant tumors ranged from 3 to 23 cm (mean, 14.4 cm). Forty-eight patients (60%) presented with symptoms. Radiographs of 76 patients demonstrated solitary masses occupying or extending into the inferior hemithorax (79%). Computed tomography (CT) of 78 lesions demonstrated lobular masses (83%) that formed at least one acute angle (96%) or only acute angles (65%) with the adjacent pleura. Heterogeneous lesion attenuation was documented in 88% of enhanced and in 68% of unenhanced CT scans. Contrast enhancement was common (62% of cases). Magnetic resonance (MR) imaging of 18 lesions demonstrated heterogeneous signal intensity on both T1- and T2-weighted images (78% and 83%, respectively). Multiplanar MR imaging allowed visualization of the diaphragm and documentation of an intrathoracic mass in all cases. LFTP are solitary lobular heterogeneous masses that occur in symptomatic adults and often affect the inferior hemithorax. Malignant lesions are radiologically indistinguishable from those with benign histologic characteristics. Radiographic and CT features characteristic of pleural location are typically absent.
© RSNA, 2003
Index Terms: Lung neoplasms, 66.317, 66.3254 • Pleura, neoplasms, 66.317, 66.3254
|
LEARNING OBJECTIVES FOR TEST 6
|
|---|
After reading this article and taking the test, the reader will be able to:
- Describe the clinical presentation of patients with LFTP.
- List the pathologic features of LFTP and address difficulties and controversies about their histologic diagnosis.
- Define the radiographic and cross-sectional imaging characteristics of LFTP.
- Discuss existing difficulties in determining the pleural origin of these intrathoracic lesions based on imaging features.
|
Introduction
|
|---|
Localized fibrous tumors are rare mesenchymal neoplasms that most commonly affect the pleura but have also been described in a number of other locations including the mediastinum and the lung. Extrathoracic localized fibrous tumors have been reported in the abdomen, the head and neck, and the central nervous system. Many names have been used to designate this neoplasm. The inconsistent nomenclature that appears in the published literature emphasizes controversies regarding the precursor cell for localized fibrous tumors and their variable microscopic appearance and unpredictable biologic behavior.
Patients with localized fibrous tumors of the pleura (LFTP) are typically adults who may present with symptoms related to local or systemic effects produced by the neoplasm or who may be entirely asymptomatic. Benign and malignant subtypes of LFTP are recognized. At gross examination, these are lobular soft-tissue masses, which are often described as pedunculated lesions arising from the visceral pleura. Radiologically, they are intrathoracic masses of variable sizes, which may not exhibit the classic imaging features described in extraparenchymal lesions. On cross-sectional images, they are well-defined lobular heterogeneous masses. Excision is curative in the majority of patients, although a small but significant number of lesions recur, undergo malignant transformation, or metastasize.
Although the most common primary pleural neoplasm is malignant mesothelioma, radiologists should also be able to identify the much rarer LFTP, as these two neoplasms have radically different prognoses. To help familiarize radiologists with the spectrum of radiologic features of LFTP, we review a large series of LFTP, with emphasis on the radiographic appearance of these lesions and their findings at computed tomography (CT), magnetic resonance (MR) imaging, angiography, and ultrasonography (US). We also describe the clinical presentation of patients with LFTP and the pathologic characteristics of these tumors and discuss their therapy and prognosis.
|
Materials and Methods
|
|---|
A retrospective review of 101 cases of localized fibrous tumors referred to the Pulmonary and Mediastinal Section of the Department of Radiologic Pathology at the Armed Forces Institute of Pathology (AFIP) between 1987 and 2001 was performed. Ten multifocal or recurrent LFTP and nine extrapleural localized fibrous tumors occurring in the mediastinum (n = 6) and in the lung (n = 3) were excluded. The remaining 82 LFTP form the basis of this review. Seventy-six lesions were evaluated with chest radiography, 78 with chest CT, 18 with MR imaging, 10 with angiography, and nine with US. Fifty-five patients were imaged with chest radiography and CT; 17 with chest radiography, CT, and MR imaging; and one with chest radiography and MR imaging. Six patients were evaluated only with CT, and three with only chest radiography.
For 80 patients, detailed clinical histories were available and were reviewed for age, gender, and clinical presentation. Surgical and pathology reports were reviewed to determine tumor size, location, pleural surface of origin, presence or absence of a pedicle, as well as gross and microscopic findings. Results of needle biopsies, when performed, were also noted. The diagnosis of localized fibrous tumor was confirmed in every case through the microscopic evaluation of glass slides prepared from the resected tissues and reviewed by an experienced thoracic pathologist in the Department of Pulmonary and Mediastinal Pathology at the AFIP. The lesions were classified as benign or malignant based on established histologic criteria, particularly the presence of more than four mitotic figures per 10 high-power fields.
All chest radiographs and CT studies were reviewed by two thoracic radiologists (M.L.R., G.F.A.), and MR imaging studies were reviewed by three thoracic radiologists (M.L.R., G.F.A., H.P.M.). Findings were recorded by consensus. Chest radiographs were evaluated to determine lesion size and location within the thorax as well as border characteristics and presence or absence of associated findings including pleural effusion and mass effect.
CT studies were performed at multiple institutions with a variety of scanners and variable scanning techniques. Sixty-six studies were performed after the administration of intravenous contrast material, and 25 were performed without contrast material (13 of these studies were performed before and after intravenous contrast material administration). Lesions were evaluated to determine location, mobility within the thorax, border characteristics, attenuation, presence or absence of calcification, and patterns of contrast enhancement.
MR imaging studies were performed on a variety of MR imaging equipment, with various combinations of axial, coronal, and sagittal planes. Fifteen lesions were imaged with T1-weighted and T2-weighted or cine gradient recalled echo sequences, and three lesions were imaged with T1-weighted sequences only. Six lesions were imaged before and after administration of intravenous gadolinium. All lesions were evaluated to determine morphologic features, signal intensity characteristics, and patterns of enhancement and to exclude involvement of adjacent structures.
|
Results
|
|---|
Patients and Clinical Presentation
There were 44 women and 38 men who ranged in age from 17 to 78 years (mean, 54.7 years). Sixty-four patients had benign LFTP (35 women, 29 men), and 18 had malignant tumors (nine women, nine men). The patients with benign LFTP ranged in age from 25 to 78 years (mean age, 55.9 years), and those with malignant LFTP ranged in age from 17 to 75 years (mean age, 52.5 years). Eighty-four percent of benign and 78% of malignant LFTP affected patients in the fifth through eighth decades of life. Clinical data (available in 80 of 82 patients) are presented in Table 1.
Operative Findings
Operative reports were available in 78 cases (60 benign, 18 malignant). Complete surgical excision was performed in all but one lesion. Thirty-two benign LFTP (53%) arose from the parietal pleura (Fig 1), and 27 (45%) from the visceral pleura (Fig 2); in one case, the pleural surface of origin was not stated. A pedicle connecting the lesion to the pleura was described in 30 (50%) lesions (Figs 2, 3); 19 (32%) had a broad attachment to the pleura (Fig 4); and in 11 cases, the presence or absence of a pedicle was not stated in the surgical report.
View larger version (156K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1. Benign LFTP. Photograph of a resected, ovoid LFTP, which arose from the parietal pleura, shows prominent blood vessels over the thin serosal lining of the tumor. The tumor was excised en bloc with a portion of the adjacent chest wall.
|
|
View larger version (141K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3. Benign LFTP. Photograph of a cut section of a pedunculated LFTP demonstrates an ovoid lobular mass with a thin pedicle (arrow) by which it was attached to the visceral pleura. Note the firm, yellow-tan appearance of the tumor.
|
|
Twelve malignant LFTP (67%) were attached to the parietal pleura and six (33%) to the visceral pleura. Eight (44%) lesions had a pedicle, and eight (44%) did not. In two cases, the nature of the pleural connection was not specified.
Pathologic Findings
Needle biopsies were performed in 27 lesions (22 benign, five malignant). The diagnosis of LFTP was established in seven benign and in one malignant LFTP based on the microscopic examination of the biopsy specimens. The remaining biopsies were inconclusive. There were 64 benign and 18 malignant LFTP. Pathology reports were available in 81 cases. Forty-nine LFTP (60%) were located in the right hemithorax, and 33 (40%) in the left. Benign lesions ranged in size from 2 to 30 cm (average size, 13.2 cm), and malignant lesions ranged in size from 3 to 23 cm (average size, 14.4 cm). Macroscopic descriptions of 63 benign LFTP noted gross evidence of hemorrhage in 27 (43%), cystic change in 14 (22%), and necrosis in three (5%) (Fig 5). Seven malignant LFTP (39%) exhibited hemorrhage, four (22%) had necrosis, and cystic change was found in three (17%).
Imaging Findings
Chest Radiography.—
Seventy-six LFTP (59 benign, 17 malignant) were imaged with radiography. Sixty (79%) lesions extended into or occupied the inferior hemithorax (Fig 6). Twenty-one of these lesions (18 benign, three malignant) abutted the ipsilateral hemidiaphragm, conformed to its shape, and simulated diaphragmatic elevation or eventration (Fig 7). The majority of the lesions that produced this finding (19 cases) occurred in the right hemithorax. Sixty-nine lesions (91%) had at least one well-defined border (Figs 6–8). Differential visualization of the lesion’s borders, a radiographic finding described as characteristic of pleural mass lesions, was noted in 25 (33%) cases (Fig 9). Radiographic demonstration of tumor extension into the fissure was seen in three (4%) benign lesions (Fig 9).
View larger version (155K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6a. Benign LFTP in an asymptomatic 29-year-old woman. Posteroanterior (PA) (a) and lateral (b) chest radiographs demonstrate an ovoid, slightly lobular mass in the left inferior hemithorax that abuts the left hemidiaphragm.
|
|
View larger version (134K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6b. Benign LFTP in an asymptomatic 29-year-old woman. Posteroanterior (PA) (a) and lateral (b) chest radiographs demonstrate an ovoid, slightly lobular mass in the left inferior hemithorax that abuts the left hemidiaphragm.
|
|
View larger version (145K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7a. Benign LFTP in a 62-year-old woman with right-sided chest pain. PA (a) and lateral (b) chest radiographs demonstrate a rounded well-defined mass of the right inferior hemithorax that conforms to the shape of the diaphragm and mimics diaphragmatic elevation. The LFTP was discovered at abdominal CT.
|
|
View larger version (120K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7b. Benign LFTP in a 62-year-old woman with right-sided chest pain. PA (a) and lateral (b) chest radiographs demonstrate a rounded well-defined mass of the right inferior hemithorax that conforms to the shape of the diaphragm and mimics diaphragmatic elevation. The LFTP was discovered at abdominal CT.
|
|
View larger version (137K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8a. Benign LFTP in a 73-year-old woman with dyspnea, weight loss, and hypoglycemia. (a, b) PA (a) and lateral (b) chest radiographs demonstrate a large mass that occupies more than half of the right hemithorax. The superior border of the lesion is lobular and well defined. (c) Photograph of a cut section of the resected mass demonstrates a lobular contour and a whorled nodular fibrous appearance. Scale is in centimeters.
|
|
View larger version (116K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8b. Benign LFTP in a 73-year-old woman with dyspnea, weight loss, and hypoglycemia. (a, b) PA (a) and lateral (b) chest radiographs demonstrate a large mass that occupies more than half of the right hemithorax. The superior border of the lesion is lobular and well defined. (c) Photograph of a cut section of the resected mass demonstrates a lobular contour and a whorled nodular fibrous appearance. Scale is in centimeters.
|
|
View larger version (122K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8c. Benign LFTP in a 73-year-old woman with dyspnea, weight loss, and hypoglycemia. (a, b) PA (a) and lateral (b) chest radiographs demonstrate a large mass that occupies more than half of the right hemithorax. The superior border of the lesion is lobular and well defined. (c) Photograph of a cut section of the resected mass demonstrates a lobular contour and a whorled nodular fibrous appearance. Scale is in centimeters.
|
|
View larger version (139K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9a. Benign LFTP in an asymptomatic 54-year-old man. (a, b) PA (a) and lateral (b) chest radiographs demonstrate an ovoid mass in the left hemithorax. The inferior border of the lesion is well defined, but its superior border is ill defined (a). The lesion is aligned along the course of the major fissure on the lateral radiograph (b). (c, d) PA (c) and lateral (d) chest radiographs obtained 6 years later demonstrate interval growth of the lesion and a change in its position within the thorax that confirms its pleural location. (e) Contrast-enhanced chest CT scan (lung window) shows the superior border of the lesion, its extension into the fissure, and a pedicle (arrow) that connected the mass to the fissural visceral pleura. (f) Contrast-enhanced chest CT scan (mediastinal window) demonstrates the heterogeneously enhancing lobular mass, which forms obtuse and acute angles with the adjacent pleura. Note associated ipsilateral pleural thickening or fluid.
|
|
View larger version (162K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9b. Benign LFTP in an asymptomatic 54-year-old man. (a, b) PA (a) and lateral (b) chest radiographs demonstrate an ovoid mass in the left hemithorax. The inferior border of the lesion is well defined, but its superior border is ill defined (a). The lesion is aligned along the course of the major fissure on the lateral radiograph (b). (c, d) PA (c) and lateral (d) chest radiographs obtained 6 years later demonstrate interval growth of the lesion and a change in its position within the thorax that confirms its pleural location. (e) Contrast-enhanced chest CT scan (lung window) shows the superior border of the lesion, its extension into the fissure, and a pedicle (arrow) that connected the mass to the fissural visceral pleura. (f) Contrast-enhanced chest CT scan (mediastinal window) demonstrates the heterogeneously enhancing lobular mass, which forms obtuse and acute angles with the adjacent pleura. Note associated ipsilateral pleural thickening or fluid.
|
|
View larger version (143K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9c. Benign LFTP in an asymptomatic 54-year-old man. (a, b) PA (a) and lateral (b) chest radiographs demonstrate an ovoid mass in the left hemithorax. The inferior border of the lesion is well defined, but its superior border is ill defined (a). The lesion is aligned along the course of the major fissure on the lateral radiograph (b). (c, d) PA (c) and lateral (d) chest radiographs obtained 6 years later demonstrate interval growth of the lesion and a change in its position within the thorax that confirms its pleural location. (e) Contrast-enhanced chest CT scan (lung window) shows the superior border of the lesion, its extension into the fissure, and a pedicle (arrow) that connected the mass to the fissural visceral pleura. (f) Contrast-enhanced chest CT scan (mediastinal window) demonstrates the heterogeneously enhancing lobular mass, which forms obtuse and acute angles with the adjacent pleura. Note associated ipsilateral pleural thickening or fluid.
|
|
View larger version (156K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9d. Benign LFTP in an asymptomatic 54-year-old man. (a, b) PA (a) and lateral (b) chest radiographs demonstrate an ovoid mass in the left hemithorax. The inferior border of the lesion is well defined, but its superior border is ill defined (a). The lesion is aligned along the course of the major fissure on the lateral radiograph (b). (c, d) PA (c) and lateral (d) chest radiographs obtained 6 years later demonstrate interval growth of the lesion and a change in its position within the thorax that confirms its pleural location. (e) Contrast-enhanced chest CT scan (lung window) shows the superior border of the lesion, its extension into the fissure, and a pedicle (arrow) that connected the mass to the fissural visceral pleura. (f) Contrast-enhanced chest CT scan (mediastinal window) demonstrates the heterogeneously enhancing lobular mass, which forms obtuse and acute angles with the adjacent pleura. Note associated ipsilateral pleural thickening or fluid.
|
|
View larger version (152K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9e. Benign LFTP in an asymptomatic 54-year-old man. (a, b) PA (a) and lateral (b) chest radiographs demonstrate an ovoid mass in the left hemithorax. The inferior border of the lesion is well defined, but its superior border is ill defined (a). The lesion is aligned along the course of the major fissure on the lateral radiograph (b). (c, d) PA (c) and lateral (d) chest radiographs obtained 6 years later demonstrate interval growth of the lesion and a change in its position within the thorax that confirms its pleural location. (e) Contrast-enhanced chest CT scan (lung window) shows the superior border of the lesion, its extension into the fissure, and a pedicle (arrow) that connected the mass to the fissural visceral pleura. (f) Contrast-enhanced chest CT scan (mediastinal window) demonstrates the heterogeneously enhancing lobular mass, which forms obtuse and acute angles with the adjacent pleura. Note associated ipsilateral pleural thickening or fluid.
|
|
View larger version (137K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9f. Benign LFTP in an asymptomatic 54-year-old man. (a, b) PA (a) and lateral (b) chest radiographs demonstrate an ovoid mass in the left hemithorax. The inferior border of the lesion is well defined, but its superior border is ill defined (a). The lesion is aligned along the course of the major fissure on the lateral radiograph (b). (c, d) PA (c) and lateral (d) chest radiographs obtained 6 years later demonstrate interval growth of the lesion and a change in its position within the thorax that confirms its pleural location. (e) Contrast-enhanced chest CT scan (lung window) shows the superior border of the lesion, its extension into the fissure, and a pedicle (arrow) that connected the mass to the fissural visceral pleura. (f) Contrast-enhanced chest CT scan (mediastinal window) demonstrates the heterogeneously enhancing lobular mass, which forms obtuse and acute angles with the adjacent pleura. Note associated ipsilateral pleural thickening or fluid.
|
|
Twenty (34%) benign and five (29%) malignant LFTP occupied more than half a hemithorax (Figs 8, 10), and only two lesions (one benign, one malignant) filled the entire hemithorax. Seventeen (29%) benign tumors and six (35%) malignant lesions produced mass effect on the adjacent structures (Fig 10). Twelve (20%) benign and four (24%) malignant LFTP were associated with an ipsilateral pleural effusion (Fig 10). Chest wall involvement manifesting as osseous changes in adjacent ribs was seen in only two (3%) cases (one benign, one malignant).
View larger version (164K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10a. Benign LFTP in a 72-year-old man with dyspnea. (a, b) PA (a) and lateral (b) chest radiographs demonstrate an enormous mass that occupies almost the entire right hemithorax and produces mass effect on the mediastinum. Note the well-defined lobular superior border of the lesion and the right pleural effusion. (c) Contrast-enhanced chest CT scan (mediastinal window) demonstrates the large heterogeneously enhancing mass in the right hemithorax, which produces mass effect on the mediastinum as well as atelectasis of the adjacent lung. Note geographic areas of low attenuation within the lesion.
|
|
View larger version (144K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10b. Benign LFTP in a 72-year-old man with dyspnea. (a, b) PA (a) and lateral (b) chest radiographs demonstrate an enormous mass that occupies almost the entire right hemithorax and produces mass effect on the mediastinum. Note the well-defined lobular superior border of the lesion and the right pleural effusion. (c) Contrast-enhanced chest CT scan (mediastinal window) demonstrates the large heterogeneously enhancing mass in the right hemithorax, which produces mass effect on the mediastinum as well as atelectasis of the adjacent lung. Note geographic areas of low attenuation within the lesion.
|
|
View larger version (140K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10c. Benign LFTP in a 72-year-old man with dyspnea. (a, b) PA (a) and lateral (b) chest radiographs demonstrate an enormous mass that occupies almost the entire right hemithorax and produces mass effect on the mediastinum. Note the well-defined lobular superior border of the lesion and the right pleural effusion. (c) Contrast-enhanced chest CT scan (mediastinal window) demonstrates the large heterogeneously enhancing mass in the right hemithorax, which produces mass effect on the mediastinum as well as atelectasis of the adjacent lung. Note geographic areas of low attenuation within the lesion.
|
|
Computed Tomography.—
Seventy-eight LFTP (61 benign, 17 malignant) were evaluated with CT, and morphologic features are summarized in Table 2. Twenty benign and five malignant LFTP were imaged before the administration of intravenous contrast material. Twelve benign tumors (60%) and all five malignant lesions (100%) exhibited heterogeneous attenuation either due to intrinsic areas of low attenuation (Figs 10, 11) or because of intralesional calcification (Fig 11). In seven benign LFTP (35%), heterogeneity was characterized as geographic (n = 6), rounded (n = 4), or linear (n = 2) areas of low attenuation within the tumor (Figs 10, 11). All five malignant neoplasms (100%) exhibited geographic (n = 4) or rounded (n = 2) areas of low attenuation (Fig 12). Eight benign LFTP (40%) exhibited homogeneous attenuation (Fig 13).
View larger version (136K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11a. Benign LFTP in an asymptomatic 39-year-old man. Unenhanced chest CT scans (mediastinal window) demonstrate a soft-tissue mass of the left inferior hemithorax with well-defined lobular borders. The mass forms acute angles with the adjacent pleural surface and contains a geographic area of low attenuation (a) and multifocal coarse calcifications (b).
|
|
View larger version (142K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11b. Benign LFTP in an asymptomatic 39-year-old man. Unenhanced chest CT scans (mediastinal window) demonstrate a soft-tissue mass of the left inferior hemithorax with well-defined lobular borders. The mass forms acute angles with the adjacent pleural surface and contains a geographic area of low attenuation (a) and multifocal coarse calcifications (b).
|
|
View larger version (160K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12a. Malignant LFTP in a 30-year-old man with chest pain. (a) PA chest radiograph demonstrates a well-marginated rounded mass in the right paravertebral inferior hemithorax. (b) Unenhanced chest CT scan (mediastinal window) demonstrates a well-defined heterogeneous mass with focal areas of low attenuation and subtle punctate calcification. Note that the lesion forms acute angles with the adjacent pleura. (c) Selective angiogram demonstrates exuberant tumor vascularity. (d) Photograph of a cut section of the resected gross specimen demonstrates a heterogeneous spherical mass with extensive necrosis, hemorrhage,and cystic change.
|
|
View larger version (134K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12b. Malignant LFTP in a 30-year-old man with chest pain. (a) PA chest radiograph demonstrates a well-marginated rounded mass in the right paravertebral inferior hemithorax. (b) Unenhanced chest CT scan (mediastinal window) demonstrates a well-defined heterogeneous mass with focal areas of low attenuation and subtle punctate calcification. Note that the lesion forms acute angles with the adjacent pleura. (c) Selective angiogram demonstrates exuberant tumor vascularity. (d) Photograph of a cut section of the resected gross specimen demonstrates a heterogeneous spherical mass with extensive necrosis, hemorrhage,and cystic change.
|
|
View larger version (141K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12c. Malignant LFTP in a 30-year-old man with chest pain. (a) PA chest radiograph demonstrates a well-marginated rounded mass in the right paravertebral inferior hemithorax. (b) Unenhanced chest CT scan (mediastinal window) demonstrates a well-defined heterogeneous mass with focal areas of low attenuation and subtle punctate calcification. Note that the lesion forms acute angles with the adjacent pleura. (c) Selective angiogram demonstrates exuberant tumor vascularity. (d) Photograph of a cut section of the resected gross specimen demonstrates a heterogeneous spherical mass with extensive necrosis, hemorrhage,and cystic change.
|
|
View larger version (121K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12d. Malignant LFTP in a 30-year-old man with chest pain. (a) PA chest radiograph demonstrates a well-marginated rounded mass in the right paravertebral inferior hemithorax. (b) Unenhanced chest CT scan (mediastinal window) demonstrates a well-defined heterogeneous mass with focal areas of low attenuation and subtle punctate calcification. Note that the lesion forms acute angles with the adjacent pleura. (c) Selective angiogram demonstrates exuberant tumor vascularity. (d) Photograph of a cut section of the resected gross specimen demonstrates a heterogeneous spherical mass with extensive necrosis, hemorrhage,and cystic change.
|
|
View larger version (157K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13. Benign LFTP in an asymptomatic 71-year-old woman. Targeted unenhanced chest CT scan (mediastinal window) demonstrates a homogeneous ovoid lobular soft-tissue mass abutting the descending aorta. Although the lesion forms acute angles with the pleura, a smoothly tapering margin (arrow) is also seen.
|
|
Sixty-six LFTP (53 benign, 13 malignant) were imaged after the administration of intravenous contrast material. Lesion enhancement was defined as an increase in attenuation compared with the attenuation of the lesion on the unenhanced CT scans or as attenuation greater than that of the adjacent chest wall musculature. Enhancement was seen in 41 (62%) lesions (37 benign, four malignant) (Fig 14). Fifty-eight (88%) lesions exhibited heterogeneous attenuation. Thin linear foci of increased attenuation consistent with intratumoral vessels were seen in 10 (15%) cases (six benign, four malignant) (Fig 15). Fifty-four (82%) lesions exhibited heterogeneous areas of low attenuation. In 40 benign LFTP (75%) low-attenuation areas were geographic (n = 33), focal (n = 27), or linear (n = 8) (Figs 10, 14, 16, 17). All 13 malignant LFTP (100%) exhibited areas of low attenuation characterized as geographic (n = 11) or focal (n = 6).
View larger version (148K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 14. Benign LFTP in a 54-year-old woman with dyspnea. Contrast-enhanced chest CT scan (mediastinal window) demonstrates a heterogeneously enhancing soft-tissue mass of the left inferior hemithorax with internal focal and linear areas of low attenuation.
|
|
View larger version (161K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15. Benign LFTP in a 54-year-old woman with chest pain and dyspnea. Contrast-enhanced chest CT scan (mediastinal window) demonstrates an enormous heterogeneously enhancing soft-tissue mass in the right hemithorax that produces mass effect on the heart. Note the serpiginous branching linear areas of enhancement consistent with intralesional vessels and the geographic and linear areas of low attenuation within the lesion. Enhancing portions of the lesion have a nodular pattern of attenuation.
|
|
View larger version (175K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16a. Benign LFTP in an asymptomatic 62-year-old man. (a) Contrast-enhanced chest CT scan (mediastinal window) demonstrates a lobular heterogeneous soft-tissue mass with geographic and focal areas of low attenuation. Note that the lesion forms acute angles with the adjacent pleura. (b) Photograph of a cut section of the gross specimen demonstrates a well-circumscribed lobular mass with a focal area of necrosis that corresponds to the low-attenuation area seen at CT.
|
|
View larger version (127K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16b. Benign LFTP in an asymptomatic 62-year-old man. (a) Contrast-enhanced chest CT scan (mediastinal window) demonstrates a lobular heterogeneous soft-tissue mass with geographic and focal areas of low attenuation. Note that the lesion forms acute angles with the adjacent pleura. (b) Photograph of a cut section of the gross specimen demonstrates a well-circumscribed lobular mass with a focal area of necrosis that corresponds to the low-attenuation area seen at CT.
|
|
View larger version (144K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 17a. Benign LFTP in a 77-year-old man with dyspnea, cough, and weight loss. (a) Contrast-enhanced chest CT scan (mediastinal window) demonstrates a large heterogeneous soft-tissue mass of lobular borders with a large ovoid area of focal low attenuation as well as smaller foci of low attenuation. (b) Sagittal US scan through the left upper quadrant allows visualization of the spleen and diaphragm as well as the supradiaphragmatic hypoechoic LFTP. (c) Photograph of a cut section of the gross specimen demonstrates a large lobular heterogeneous soft-tissue mass with a nodular cut surface as well as areas of necrosis (arrow) and hemorrhage (arrowhead).
|
|
View larger version (139K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 17b. Benign LFTP in a 77-year-old man with dyspnea, cough, and weight loss. (a) Contrast-enhanced chest CT scan (mediastinal window) demonstrates a large heterogeneous soft-tissue mass of lobular borders with a large ovoid area of focal low attenuation as well as smaller foci of low attenuation. (b) Sagittal US scan through the left upper quadrant allows visualization of the spleen and diaphragm as well as the supradiaphragmatic hypoechoic LFTP. (c) Photograph of a cut section of the gross specimen demonstrates a large lobular heterogeneous soft-tissue mass with a nodular cut surface as well as areas of necrosis (arrow) and hemorrhage (arrowhead).
|
|
View larger version (130K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 17c. Benign LFTP in a 77-year-old man with dyspnea, cough, and weight loss. (a) Contrast-enhanced chest CT scan (mediastinal window) demonstrates a large heterogeneous soft-tissue mass of lobular borders with a large ovoid area of focal low attenuation as well as smaller foci of low attenuation. (b) Sagittal US scan through the left upper quadrant allows visualization of the spleen and diaphragm as well as the supradiaphragmatic hypoechoic LFTP. (c) Photograph of a cut section of the gross specimen demonstrates a large lobular heterogeneous soft-tissue mass with a nodular cut surface as well as areas of necrosis (arrow) and hemorrhage (arrowhead).
|
|
MR Imaging.—
Eighteen LFTP (13 benign, five malignant) were evaluated with MR imaging. Coronal or sagittal images were obtained in all cases. Eleven (85%) benign and four (80%) malignant LFTP manifested as lobular masses (Fig 18). Chest wall involvement was exhibited by one benign (8%) and one malignant LFTP (20%) (Fig 19), and diaphragm involvement was evident in two malignant LFTP (40%) (Fig 20). Mass effect on the diaphragm was documented in 12 (67%) cases (eight benign, four malignant) on coronal or sagittal images (Figs 18, 19). Patterns of signal intensity are summarized in Table 3. Six lesions (five benign, one malignant) were imaged after the administration of intravenous gadolinium, and all exhibited heterogeneous contrast enhancement (Figs 18, 20).
View larger version (151K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 18a. Benign LFTP in an asymptomatic 68-year-old man. (a) Coronal T1-weighted MR image demonstrates a large lobular heterogeneous mass of intermediate signal intensity with linear areas of high signal intensity. Note mass effect on the ipsilateral hemidiaphragm and mediastinum. (b) Coronal T1-weighted MR image obtained after intravenous administration of gadolinium demonstrates heterogeneous patchy multifocal enhancement within the lesion.
|
|
View larger version (165K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 18b. Benign LFTP in an asymptomatic 68-year-old man. (a) Coronal T1-weighted MR image demonstrates a large lobular heterogeneous mass of intermediate signal intensity with linear areas of high signal intensity. Note mass effect on the ipsilateral hemidiaphragm and mediastinum. (b) Coronal T1-weighted MR image obtained after intravenous administration of gadolinium demonstrates heterogeneous patchy multifocal enhancement within the lesion.
|
|
View larger version (174K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 19a. Benign LFTP in a 48-year-old man with chest pain. (a) Sagittal T1-weighted MR image demonstrates a lobular ovoid mass of intermediate signal intensity located in the right inferior hemithorax. Note mass effect on the liver and focal chest wall invasion. (b) Sagittal T2-weighted MR image at the same level demonstrates heterogeneous high signal intensity with flow void areas within the lesion that represent vessels and intrinsic low-signal-intensity septa (arrow).
|
|
View larger version (187K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 19b. Benign LFTP in a 48-year-old man with chest pain. (a) Sagittal T1-weighted MR image demonstrates a lobular ovoid mass of intermediate signal intensity located in the right inferior hemithorax. Note mass effect on the liver and focal chest wall invasion. (b) Sagittal T2-weighted MR image at the same level demonstrates heterogeneous high signal intensity with flow void areas within the lesion that represent vessels and intrinsic low-signal-intensity septa (arrow).
|
|
View larger version (153K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 20a. Malignant LFTP in a 53-year-old woman with abdominal pain. (a) Axial T1-weighted MR image shows a mass of intermediate to low signal intensity in the right diaphragmatic region, which produces mass effect on the diaphragm and indents the liver. (b) Sagittal T1-weighted MR image obtained after intravenous administration of gadolinium shows heterogeneous contrast enhancement and extension through the diaphragm. Note that a large portion of the mass is intrahepatic and thus a tumor of liver origin would have to be considered. Diaphragm invasion was documented at surgery.
|
|
View larger version (172K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 20b. Malignant LFTP in a 53-year-old woman with abdominal pain. (a) Axial T1-weighted MR image shows a mass of intermediate to low signal intensity in the right diaphragmatic region, which produces mass effect on the diaphragm and indents the liver. (b) Sagittal T1-weighted MR image obtained after intravenous administration of gadolinium shows heterogeneous contrast enhancement and extension through the diaphragm. Note that a large portion of the mass is intrahepatic and thus a tumor of liver origin would have to be considered. Diaphragm invasion was documented at surgery.
|
|
Angiography.—
Ten LFTP were studied with angiography (seven benign, three malignant). All lesions (100%) exhibited exuberant tumor vascularity (Fig 12c).
Ultrasonography.—
Nine benign LFTP were imaged with US. Six masses (67%) were heterogeneous and exhibited hypoechoic and hyperechoic areas but no cysts or calcification. US visualization of the diaphragm was documented in five cases, established the intrathoracic location of the lesion in all, and showed mass effect without invasion in three (Fig 17b).
Radiologic Reports.—
A review of the radiologic reports generated at the time the lesions were originally imaged (n = 80) showed that the diagnosis of LFTP was not mentioned in the preoperative differential diagnosis for 43 (54%) cases (33 benign, 10 malignant). The specific diagnosis of LFTP was included in the differential diagnosis for 21 (26%) lesions (15 benign, six malignant), and 16 (20%) lesions (14 benign, two malignant) were characterized as pleural in location.
|
Discussion
|
|---|
Primary pleural neoplasms are rare and represent less than 5% of all pleural neoplasia. The most common primary pleural neoplasm is malignant mesothelioma, a highly aggressive malignancy that is associated with asbestos exposure. Malignant mesothelioma is characterized by diffuse circumferential pleural involvement and a poor prognosis (1). The first report of a primary pleural neoplasm dates back to 1767 and is attributed to Lieutaud (2). Wagner published the first microscopic description of a primary diffuse pleural neoplasm in 1870 and proposed that the tumor was derived from the endothelium of the pleural lymphatics (3,4). In 1931, Klemperer and Rabin classified primary pleural neoplasms as localized and diffuse types and proposed that a submesothelial mesenchymal cell was the cell of origin for the localized type (5). LFTP are rare neoplasms; only over 600 cases have been reported in the scientific literature (6). In a 1978 review of 60 cases of LFTP, Okike and colleagues (7) reported a prevalence of only 2.8 cases per 100,000 registrations at their institution, the Mayo Clinic.
Pathogenesis
Different theories about the cell of origin for LFTP have been proposed and probably account for the varied nomenclature used to designate this rare neoplasm. Localized mesothelioma, fibrous mesothelioma, benign fibrous mesothelioma, localized fibrous mesothelioma, benign mesothelioma, benign localized mesothelioma, fibrosing mesothelioma, and mesothelial fibroma represent nomenclature that alludes to early theories supporting a mesothelial cell of origin (3,8–12). Terms such as subpleural fibroma, submesothelial fibroma, and submesothelioma suggest a submesothelial precursor cell (3,10). Pleural fibroma, benign pleural fibroma, pleural fibromyxoma, solitary fibrous tumor of the pleura, and localized fibrous tumor of the serosal cavities are additional terms that have been used to designate these lesions (10,11,13). The currently accepted nomenclature is localized fibrous tumor of the pleura, and a derivation from submesothelial mesenchymal cells with a fibroblastic differentiation is generally acknowledged (11).
Lesions of similar histologic characteristics have been reported in extrapleural thoracic locations, including the mediastinum, lung, pericardium, and heart (14–16). Yousem and Flynn (17) described three intrapulmonary localized fibrous tumors and suggested a common origin for this subset of lesions from tissues in the interlobular septa. Localized fibrous tumors have also been reported in the abdomen (liver, peritoneum, and retroperitoneum) and in the meninges, orbit, thyroid, salivary gland, and the soft tissues including the breast (15,16,18). It has been suggested that the upper respiratory tract may be a preferred extrathoracic location, with reports of localized fibrous tumors arising in the nose, paranasal sinuses, parapharyngeal tissues, nasopharynx and epiglottis (15,19).
Clinical Characteristics
LFTP affect male and female patients, with a slight female predominance reported in some studies (3). Women represented 55% of patients with benign LFTP and 50% of patients with malignant LFTP in our series. Affected patients display a wide age range (5–87 years), with the majority of cases reported in the 6th and 7th decades of life and a reported mean age of 50–57 years (3,20,21). Although 83% of the patients in our series were older than 40 years, only 41% were in the 6th and 7th decades of life. LFTP are not thought to be related to exposure to cigarette smoke, asbestos, or other environmental pollutants (22,23). However, there are at least two case reports of patients with LFTP who were exposed to asbestos and one of a patient who developed a LFTP following thoracic irradiation for the treatment of a chest wall keloid (24,25).
Up to 50% of patients with LFTP, particularly those with small neoplasms, may be entirely asymptomatic, and the tumor is discovered incidentally because of radiographs obtained for other reasons (3,21,26). When signs and symptoms (particularly digital clubbing and hypertrophic osteoarthropathy) are present, they are usually associated with larger tumors and may occur more frequently in association with malignant subtypes of LFTP (7,27). Interestingly, the average size of LFTP that affected asymptomatic individuals in our series was 10.5 cm, whereas the average size of those that occurred in symptomatic patients was 16.6 cm. Studies of patients with LFTP published from 1942 to 1972 reported that 72% of patients were symptomatic at presentation, whereas studies published between 1973 and 1980 reported symptoms in only 54% of patients. This decrease in the prevalence of symptoms in patients with LFTP may relate to more widespread imaging of asymptomatic populations and the resultant detection of a larger number of incidental tumors (3).
Reported symptoms are similar to those exhibited by our patients and include respiratory and thoracic complaints such as cough, dyspnea, hemoptysis, chest pain, chest heaviness, and the sensation of a mass moving within the chest (3,21) (Table 1). Abdominal pain has been reported in patients with supradiaphragmatic tumors (28). Systemic complaints may occur and include chills, sweats, weakness, and weight loss (3). Paraneoplastic syndromes such as hypoglycemia, digital clubbing, and hypertrophic osteoarthropathy are uncommon, but when they are associated with an intrathoracic mass they may suggest the diagnosis of LFTP (4,29,30). These systemic effects typically occur with large tumors and generally resolve after excision of the neoplasms but may recur with subsequent tumor recurrences (12,30–32). Non–islet cell tumor hypoglycemia has been described in association with both epithelial and mesenchymal neoplasms, including LFTP (30,32–34). Many theories have been proposed to explain this phenomenon, including increased glucose consumption by the tumor; proliferation of insulin receptors; impaired growth hormone counter-regulatory responses to hypoglycemia; and tumor secretion of insulin-like substances, such as insulin-like growth factor 2 (IGF-2) and a high molecular weight ("big") IGF-2 (4,30,32,35–38). In some patients, hypoglycemic coma may be the presenting manifestation of a LFTP (34). Hypertrophic osteoarthropathy may relate to hyaluronic acid production and its osteolytic effects and is reported in 17%–35% of cases (4,8,37,39). Although hypertrophic osteoarthropathy has been described in cases of lung carcinoma, malignant pleural mesothelioma, and even empyema and other thoracic infections, LFTP may produce it more commonly (4). Interestingly, none of our patients presented with hypertrophic osteoarthropathy.
Gross Features
LFTP are typically solitary lesions with rare occurrences of conglomerate or multifocal masses. Sixty-six percent to 70% of localized fibrous tumors arise from the visceral pleura, and nearly half are pedunculated, with the vascular supply to the tumor contained within the pedicle (21,40) (Figs 2, 3). Although a pedicle was present in 49% of our cases, 55% of the lesions arose from the parietal pleural surface (Fig 1). This discrepancy may relate to selection bias, because our cases were collected through consultation for second-opinion diagnosis or through case contributions by residents attending AFIP courses, and only cases with imaging studies were included. The AFIP series published by England and colleagues (21), based on a larger number of cases (n = 223) submitted to the Institute before 1988, documented origin of LFTP from the visceral pleura in 66% of cases. Adhesions to the adjacent pleural surfaces and pericardium are common (3,21). LFTP are usually well-circumscribed masses with lobular or smooth external surfaces and a thin, glistening translucent serosa through which a network of prominent blood vessels may be seen (Fig 1) (40). The cut surface is firm, pink-white or yellow-tan and often exhibits a whorled or nodular pattern (Figs 3, 8c). Areas of necrosis, hemorrhage, or cystic degeneration may be evident, particularly in large or malignant lesions (Figs 5, 12d, 16b, 17c).
Histologic Characteristics
England and colleagues (21) proposed that LFTP originated from the submesothelial connective tissues and suggested a primitive multipotential cell of mesenchymal differentiation as the cell of origin. At histologic analysis, localized fibrous tumors appear as low-grade neoplasms of variable cellularity. The tumor cells are ovoid to spindle-shaped with round to oval nuclei, an evenly distributed fine chromatin, inconspicuous nucleoli, and bipolar faintly eosinophilic cytoplasm with indistinct cell borders (Fig 21). Nuclear pleomorphism is minimal and mitoses are usually rare or absent. Cellularity is variable and is inversely related to collagen content (21). Collagen ranges from wispy fibrils surrounding tumor cells in hypercellular areas to thick, dense, wirelike or "ropy" collagen forming sclerotic zones in hypocellular areas (Figs 21, 22). Tumors are usually well vascularized with vessels of varying sizes (23). Degenerative features including myxoid change and degeneration of collagen may occur (41). Microscopic examination reveals a variety of architectural patterns, with the most frequent being an intermingling of tumor cells and collagen in a random fashion, the so-ca
Top
Abstract
LEARNING OBJECTIVES FOR TEST...
