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From the Archives of the AFIP

Localized Fibrous Tumors of the Pleura¹

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).

View larger version (156K): [in a new window]   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 (131K): [in a new window]   Figure 2.  Benign LFTP. Intraoperative photograph shows a pedunculated LFTP, which arises from the visceral pleura. The surgical forceps hold the adjacent partially collapsed lung.

View larger version (141K): [in a new window]   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.

View larger version (162K): [in a new window]   Figure 4.  Benign LFTP. Photograph of a benign LFTP demonstrates a spherical lobular mass. Note the site of prior broad attachment (arrows) of the lesion to the parietal pleura.

View larger version (117K): [in a new window]   Figure 5.  Benign LFTP. Photograph of a cut section of a benign LFTP demonstrates an ovoid lobular mass with extensive internal hemorrhage and necrosis.

View larger version (155K): [in a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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.

View larger version (164K): [in a new window]   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 a new window]   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 a new window]   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.

View larger version (136K): [in a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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.

View larger version (148K): [in a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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).

View larger version (151K): [in a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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 a new window]   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.

View larger version (188K): [in a new window]   Figure 21a.  Benign LFTP. (a, b) High-power (original magnification, x400) (a) and intermediate-power (original magnification, x200) (b) photomicrographs (hematoxylin-eosin [H-E] stain) demonstrate the bland, low-grade appearance of spindle-shaped tumor cells (a) that are arranged in a haphazard or so-called patternless pattern (b), the classic appearance of localized fibrous tumors. (c, d) High-power photomicrographs (original magnification, x400; H-E stain) of the same neoplasm demonstrate the variable cellularity characteristic of localized fibrous tumors. A hypercellular area (c) is composed of abundant spindle-shaped cells with a paucity of collagen fibers, whereas a hypocellular area (d) demonstrates abundant collagen (*) between tumor cells.

View larger version (189K): [in a new window]   Figure 21b.  Benign LFTP. (a, b) High-power (original magnification, x400) (a) and intermediate-power (original magnification, x200) (b) photomicrographs (hematoxylin-eosin [H-E] stain) demonstrate the bland, low-grade appearance of spindle-shaped tumor cells (a) that are arranged in a haphazard or so-called patternless pattern (b), the classic appearance of localized fibrous tumors. (c, d) High-power photomicrographs (original magnification, x400; H-E stain) of the same neoplasm demonstrate the variable cellularity characteristic of localized fibrous tumors. A hypercellular area (c) is composed of abundant spindle-shaped cells with a paucity of collagen fibers, whereas a hypocellular area (d) demonstrates abundant collagen (*) between tumor cells.

View larger version (186K): [in a new window]   Figure 21c.  Benign LFTP. (a, b) High-power (original magnification, x400) (a) and intermediate-power (original magnification, x200) (b) photomicrographs (hematoxylin-eosin [H-E] stain) demonstrate the bland, low-grade appearance of spindle-shaped tumor cells (a) that are arranged in a haphazard or so-called patternless pattern (b), the classic appearance of localized fibrous tumors. (c, d) High-power photomicrographs (original magnification, x400; H-E stain) of the same neoplasm demonstrate the variable cellularity characteristic of localized fibrous tumors. A hypercellular area (c) is composed of abundant spindle-shaped cells with a paucity of collagen fibers, whereas a hypocellular area (d) demonstrates abundant collagen (*) between tumor cells.

View larger version (183K): [in a new window]   Figure 21d.  Benign LFTP. (a, b) High-power (original magnification, x400) (a) and intermediate-power (original magnification, x200) (b) photomicrographs (hematoxylin-eosin [H-E] stain) demonstrate the bland, low-grade appearance of spindle-shaped tumor cells (a) that are arranged in a haphazard or so-called patternless pattern (b), the classic appearance of localized fibrous tumors. (c, d) High-power photomicrographs (original magnification, x400; H-E stain) of the same neoplasm demonstrate the variable cellularity characteristic of localized fibrous tumors. A hypercellular area (c) is composed of abundant spindle-shaped cells with a paucity of collagen fibers, whereas a hypocellular area (d) demonstrates abundant collagen (*) between tumor cells.

View larger version (179K): [in a new window]   Figure 22.  Benign LFTP. High-power photomicrograph (original magnification, x400; H-E stain) of a benign LFTP demonstrates the characteristic ropy collagen that occurs in the hypocellular areas of these lesions.

View larger version (181K): [in a new window]   Figure 23.  Benign LFTP. Low-power photomicrograph (original magnification, x100; H-E stain) demonstrates the second most commonly encountered histologic pattern (hemangiopericytoma-like) characterized by staghorn-like vessels.

View larger version (189K): [in a new window]   Figure 24.  Malignant LFTP. High-power photomicrograph (original magnification, x400; H-E stain) demonstrates five mitotic figures within this one high-power field. Note the nuclear pleomorphism that may also characterize malignant LFTP.

View larger version (130K): [in a new window]   Figure 25.  Benign LFTP in a 55-year-old man undergoing evaluation for HIV disease. Unenhanced chest CT scan (bone window) demonstrates a small well-defined mass of the left superior hemithorax that forms obtuse angles with the adjacent pleural surfaces.

View larger version (161K): [in a new window]   Figure 26a.  Malignant LFTP in an asymptomatic 37-year-old man. (a) PA chest radiograph demonstrates a lobular mass in the right cardiophrenic angle. Note poor visualization of the superolateral border of the lesion. (b) Unenhanced chest CT scan (mediastinal window) demonstrates a spherical heterogeneous right paracardiac mass that produces mass effect on the heart and perilesional atelectasis. Note the small ipsilateral right pleural effusion.

View larger version (127K): [in a new window]   Figure 26b.  Malignant LFTP in an asymptomatic 37-year-old man. (a) PA chest radiograph demonstrates a lobular mass in the right cardiophrenic angle. Note poor visualization of the superolateral border of the lesion. (b) Unenhanced chest CT scan (mediastinal window) demonstrates a spherical heterogeneous right paracardiac mass that produces mass effect on the heart and perilesional atelectasis. Note the small ipsilateral right pleural effusion.

View larger version (146K): [in a new window]   Figure 27a.  Benign LFTP in a 27-year-old woman with chest pain. Contrast-enhanced chest CT scans (mediastinal window) demonstrate a heterogeneously enhancing mass of the left middle hemithorax that produces pressure erosion on an adjacent rib. The lesion forms obtuse and acute angles with the adjacent pleura and exhibits a smoothly tapering margin (b). Note enhancing serpiginous linear structures within the lesion (a), which likely represent vascular structures.

View larger version (142K): [in a new window]   Figure 27b.  Benign LFTP in a 27-year-old woman with chest pain. Contrast-enhanced chest CT scans (mediastinal window) demonstrate a heterogeneously enhancing mass of the left middle hemithorax that produces pressure erosion on an adjacent rib. The lesion forms obtuse and acute angles with the adjacent pleura and exhibits a smoothly tapering margin (b). Note enhancing serpiginous linear structures within the lesion (a), which likely represent vascular structures.

View larger version (133K): [in a new window]   Figure 28a.  Malignant LFTP in an asymptomatic HIV-positive 28-year-old woman. (a) Contrast-enhanced chest CT scan (mediastinal window) demonstrates an irregular soft-tissue mass in the left middle hemithorax that exhibits heterogeneous enhancement and internal geographic areas of low attenuation. (b) Photograph of the resected specimen demonstrates a centrally necrotic mass. Note that complete excision of the LFTP required a pneumonectomy.

View larger version (155K): [in a new window]   Figure 28b.  Malignant LFTP in an asymptomatic HIV-positive 28-year-old woman. (a) Contrast-enhanced chest CT scan (mediastinal window) demonstrates an irregular soft-tissue mass in the left middle hemithorax that exhibits heterogeneous enhancement and internal geographic areas of low attenuation. (b) Photograph of the resected specimen demonstrates a centrally necrotic mass. Note that complete excision of the LFTP required a pneumonectomy.

View larger version (142K): [in a new window]   Figure 29a.  Benign LFTP in a 64-year-old woman who presented with confusion and hypoglycemia. (a) Sagittal T1-weighted MR image demonstrates a large soft-tissue mass of heterogeneous intermediate signal intensity in the right hemithorax that produces mass effect on the hemidiaphragm. Note flow void foci consistent with tumor vessels. (b) Sagittal T2-weighted MR image at the same level demonstrates an overall heterogeneous increase in signal intensity in the lesion with multiple hyperintense areas.

View larger version (145K): [in a new window]   Figure 29b.  Benign LFTP in a 64-year-old woman who presented with confusion and hypoglycemia. (a) Sagittal T1-weighted MR image demonstrates a large soft-tissue mass of heterogeneous intermediate signal intensity in the right hemithorax that produces mass effect on the hemidiaphragm. Note flow void foci consistent with tumor vessels. (b) Sagittal T2-weighted MR image at the same level demonstrates an overall heterogeneous increase in signal intensity in the lesion with multiple hyperintense areas.