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Like its counterpart in the pleural cavity, solitary fibrous tumors have been described in nearly every organ and site. The unifying characteristic is the positivity of the spindle cells for CD34.


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A partial listing of sites includes:

Orbit, dura/meninges, paranasal sinuses and upper respiratory tract, thyroid, sublingual gland, lung, mediastinum, pericardium, gastrointestinal tract, liver, kidney, peritoneum, retroperitoneum/pelvis, adrenal gland, cauda equina/spinal cord, ovary, uterine cervix/vagina, bladder, prostate, scrotum, testicular tunica vaginalis, trunk/skin, soft tissue, periosteum, and extremities.


Solitary fibrous tumor of the cerebellopontine angle with salivary gland heterotopia: a unique presentation.

Rodriguez F, Scheithauer BW, Ockner DM, Giannini C.

Department of Pathology, Mayo Foundation, Rochester, Minnesota; and dagger Christiana Care Health Services, Wilmington, Delaware.
Am J Surg Pathol. 2004 Jan; 28(1): 139-42. Abstract quote  

SUMMARY: We report the unique association of a solitary fibrous tumor of the cerebellopontine angle with ectopic salivary gland tissue in a 53-year-old woman. The patient, diagnosed 21 years earlier with a right cerebellopontine angle fibrous meningioma, presented with a recurrent mass, which, upon surgical removal, showed features of a solitary fibrous tumor. Strong and diffuse immunoreactivity to CD34 and BCL-2 and a negative epithelial membrane antigen immunostain confirmed the diagnosis.

Admixed with the spindle cell neoplasm, a bland glandular element composed of small glands and variably dilated tubules was noted. The vague tubuloacinar arrangement of the glands and the presence of acinar cells with a granular, periodic acid-Schiff-positive, basophilic cytoplasm, resembling serous type acini, were features of benign, although ectopic, salivary gland tissue.

The presence of a myoepithelial cell layer, surrounding some of the acini and highlighted by the smooth muscle actin immunostain, strengthened this interpretation.

Solitary fibrous tumors in the central nervous system. A clinicopathologic review of 18 cases and comparison to meningeal hemangiopericytomas.

Tihan T, Viglione M, Rosenblum MK, Olivi A, Burger PC.

Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Md, USA.

Arch Pathol Lab Med 2003 Apr;127(4):432-9 Abstract quote

CONTEXT: Solitary fibrous tumors (SFTs) of the central nervous system are rare neoplasms that usually present as dura-based masses and clinically resemble meningiomas. Histologically, they can be similar to fibrous meningioma or hemangiopericytoma (HPC). In particular, densely cellular regions seen in some SFTs can be indistinguishable from HPC. Little is known about the biological behavior of SFTs, although most seem amenable to total resection.

OBJECTIVES: To define the clinicopathologic spectrum of SFTs in the central nervous system and to outline their differences from HPC and meningioma.

DESIGN: We present the clinicopathologic features of 18 patients with SFT and compare them with those of an age- and sex-matched cohort of HPCs.

RESULTS: Eleven SFTs were supratentorial, 3 were infratentorial, and 4 were intraspinal. Four of the 18 tumors were intra-axial (2 in the lateral ventricles and 2 within the spinal cord). Histologically, SFTs were similar to their soft tissue counterparts. Six tumors (6/18) had densely cellular regions, and 1 tumor showed frankly anaplastic features. All but 3 patients underwent gross total resection, and there were no metastases or tumor-related mortalities during the median follow-up of 40 months. In contrast, there were 15 local recurrences (83%), 5 extracranial metastases (27%), and 4 tumor-related deaths (22%) in the HPC cohort.

CONCLUSIONS: Our study presents the clinicopathologic features of SFT as a distinct entity from both meningioma and HPC. We also present unusual examples of anaplastic, intraventricular, and intramedullary spinal SFTs that expand the clinicopathologic spectrum of these uncommon and sometimes diagnostically difficult neoplasms.


Large Solitary Fibrous Tumor of the Kidney Report of Two Cases and Review of the Literature

Jun Wang, M.D.; Daniel A. Arber, M.D.; Kenneth Frankel, M.D.; Lawrence M. Weiss, M.D.

From the Department of Pathology and Laboratory Medicine (J.W.), Loma Linda University Medical Center, Loma Linda, California; Department of Anatomic Pathology (D.A.A., L.M.W.), City of Hope National Medical Center, Duarte, California; and the Department of Anatomic and Clinical Pathology (K.F.), Citrus Valley Medical Center, Covina, California, U.S.A.

Am J Surg Pathol 2001;25:1194-1199 Abstract quote

Solitary fibrous tumors are spindle cell neoplasms frequently arising in the serosal surface as well as a variety of other sites.

We report two cases of large solitary fibrous tumor arising in the kidney, clinically thought to be renal cell carcinoma, in 41-and 72-year-old men. Although large in size (13.0 and 14.0 cm in greatest dimension, respectively), both lesions were well circumscribed and composed of a mixture of spindle cells and dense collagenous bands with no areas of necrosis or cystic changes noted macroscopically or microscopically. Immunohistochemical studies revealed reactivity for vimentin, CD34, collagen IV, and bcl-2 protein in both cases, with no staining for keratin, S-100 protein, or muscle markers, confirming the diagnosis of solitary fibrous tumor of the kidney.

Solitary fibrous tumor of the kidney is rare but may present as a large mass that may be clinically confused with carcinoma or sarcoma.

Solitary fibrous tumor of the larynx: a case report and review of the literature.

Dotto JE, Ahrens W, Lesnik DJ, Kowalski D, Sasaki C, Flynn S.

Department of Pathology, Yale-New Haven Hospital, Yale University School of Medicine, New Haven, CT, USA.

Arch Pathol Lab Med. 2006 Feb;130(2):213-6. Abstract quote


Solitary fibrous tumors are relatively rare mesenchymal neoplasms that were originally described as pleural- or peritoneal-based lesions.
Although they were considered a form of mesothelioma, subsequent investigation failed to reveal mesothelial differentiation. Characterization of their histologic and immunohistochemical features, as well as identification in a multitude of nonmesothelial-based locations has further served to distinguish these lesions from the more diffuse and aggressive mesothelioma.
Reports of solitary fibrous tumor in the larynx are extremely rare. We report a case of solitary fibrous tumor of the larynx in a 38-year-old man.

Clinicopathological features of solitary fibrous tumor of the meninges: An immunohistochemical reappraisal of cases previously diagnosed to be fibrous meningioma or hemangiopericytoma.

Suzuki SO, Fukui M, Nishio S, Iwaki T.

Departments of Neuropathology and; Neurosurgery, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.

Pathol Int 2000 Oct;50(10):808-17 Abstract quote

Cases of solitary fibrous tumor (SFT) of the meninges are increasingly being reported. However, the real incidence of SFT among meningeal tumors has yet to be determined.

We therefore clinicopathologically re-examined 64 meningeal tumors originally diagnosed to be either fibrous meningioma (FM group, n = 46) or hemangiopericytoma (HPC group, n = 18) while paying special attention to SFT.

We thus reclassified one case from the FM group (2%) and one case from the HPC group (6%) to be SFT, both of which showed diffuse CD34-immunoreactivity and dense intercellular reticulin fibers but neither epithelial membrane antigen nor S-100 protein expression. The MIB-1 staining index of these cases were 6. 2% and 3.9%, respectively. The former recurred 15 years after the initial surgery and the patient underwent a second removal of the tumor. The patient has been alive with no evidence of recurrence for 7 years after the second surgery. The latter patient has been alive with no evidence of recurrence for 3 years postoperatively.

The results confirmed that the incidence of SFT among meningeal tumors is relatively low, however, because of its clinically indolent nature, a careful histochemical examination is necessary to differentiate SFT from other neoplasms with a more aggressive nature. Our findings emphasize the need to clinically recognize this lesion as a distinct entity.


Widely invasive solitary fibrous tumor of the sphenoid sinus, cavernous sinus, and pituitary fossa.

Cassarino DS, Auerbach A, Rushing EJ.

Ann Diagn Pathol. 2003 Jun;7(3):169-73. Abstract quote

Solitary fibrous tumor is a spindle cell tumor first described in the pleura, but also found in multiple extrathoracic sites including the meninges, orbit, nasal and paranasal sinuses. No cases have been previously reported in the cavernous sinus or pituitary fossa.

We present the case of a 54-year-old woman who presented with progressive amaurosis. On imaging studies, a widely infiltrative lesion involving the pituitary fossa, sphenoid sinus, cavernous sinus, carotid artery, medial temporal, ethmoid, and pterygoid bones, and extending into the nasopharynx was discovered; impression was a malignant tumor originating in the pituitary fossa. At surgery, the tumor was only partially resectable because of extensive bony invasion and encasement of the carotid artery, and was found to compress but not invade the pituitary gland.

Histology showed a spindle cell proliferation with a dense, hyalinized collagenous stroma and dilated vascular spaces, some showing a staghorn-like appearance. Areas of cellular pleomorphism and increased cellularity were present, but few mitoses were identified. Immunohistochemistry showed strong positivity with CD34, factor XIIIa, CD99, and Bcl-2. There was scattered cyclin D1, mib-1, and p53 positivity. Muscle, epithelial, vascular, and melanocytic markers were negative.

These results led to the diagnosis of solitary fibrous tumor. The size, extensive invasion, and bony destruction indicated a tumor with at least low malignant potential. The occurrence of solitary fibrous tumors in the pituitary fossa and sinuses of the head and neck is rare, but must be considered in the differential diagnosis of spindle cell lesions in these regions.

Solitary fibrous tumors of the skin: a clinicopathologic study of 10 cases and review of the literature.

Department of Pathology, Georgetown University Medical Center, Washington, DC, USA.


J Cutan Pathol. 2007 Nov;34(11):844-50. Abstract quote

Solitary fibrous tumor (SFT) is a relatively uncommon neoplasm that most commonly arises in the pleura. However, SFT is now known to affect various other anatomic sites as well, including rare examples in the skin, where the histologic features of this lesion may create diagnostic confusion with a variety of other spindle-cell tumors.

In order to further the characterization of cutaneous SFT, all available cases of that entity were retrieved from the authors' institutional files. Immunohistochemical analysis for CD-34, CD-99, vimentin, bcl-2, factor XIIIa, S100 protein, smooth muscle actin, pankeratin, epithelial membrane antigen (EMA) and desmin was performed on those neoplasms and the corresponding clinical information was obtained whenever possible.

There were eight men and two women in the study group, with a median age of 43 years. Sites of involvement included the trunk (two cases), cheek (two), scalp (one), forehead (one), lip (one), temple (one), heel (one) and toe (one). All patients were treated with local excision; only one lesion recurred locally, but it required multiple re-excisions. All of the neoplasms were composed of bland spindle cells with a variably fibrous but focally hyalinized collagenous stroma. A variety of case-specific growth patterns were observed. Mitoses were generally rare, ranging from 0 to 3 per 10 x400 microscopic fields. Immunostains showed reactivity for vimentin in all SFTs, CD-34 in 8 of 10 cases, CD-99 and bcl-2 in 4 of 10 (each) and smooth-muscle actin in 3 of 10 cases. None of the lesions was labeled for factor XIIIa, keratin, EMA, desmin or S100 protein. SFT of the skin appears to be a 'borderline' neoplasm that only uncommonly recurs.

Immunoreactivity for CD-34, - especially together with bcl-2 or CD-99, or both - is helpful in identifying this tumor.
Solitary fibrous tumor of the skin.

Hardisson D, Cuevas-Santos J, Contreras F.

Department of Pathology, University General Hospital of Guadalajara, Alcala University, Spain.
J Am Acad Dermatol. 2002 Feb;46(2 Suppl Case Reports):S37-40. Abstract quote  

Solitary fibrous tumor (SFT) is an uncommon tumor initially reported in the pleura but recently described in other sites of the body.

We report a SFT of the skin that presented as painless nodule located in the right cheek in a 56-year-old woman. Histologically, the tumor was composed of spindle-shaped cells arranged in a patternless pattern of short and narrow fascicles with interspersed bundles of thick collagen, and numerous blood vessels with a focally hemangiopericytoma-like appearance. Immunohistochemically, the tumor cells strongly expressed vimentin, CD34 and bcl-2. The lesion was excised and the patient remains well at 16-month follow-up.

This case presented some diagnostic difficulty because of its unusual location, and had to be distinguished from other superficial soft tissue tumors. Recognition of SFT in the skin is important to avoid possible confusion with a variety of spindle cell neoplasms with different biologic potential.

Solitary Fibrous Tumor of the Thyroid Gland Report of Seven Cases

Ingrid Rodriguez, M.D. ; Enrique Ayala, M.D. ; Carmelo Caballero, M.D. ; Concepción De Miguel, M.D. ; Xavier Matias-Guiu, M.D. ; Antonio L. Cubilla, M.D. ; Juan Rosai, M.D.

From Hospital de la Santa Creu i Sant Pau (I.R., X.M.-G.), Barcelona, Spain; Instituto de Patología e Investigación (I.R., E.A., C.C., A.L.C.), Asunción, Paraguay; Hospital Virgen del Camino (C.M.), Pamplona, Spain; and Istituto di Tumori (J.R.), Milano, Italy.

Am J Surg Pathol 2001;25:1424-1428 Abstract quote

Solitary fibrous tumor is a soft tissue neoplasm initially described in the pleura but subsequently reported in a wide variety of locations. The clinical behavior is usually benign, but the existence of aggressive cases has been documented both in the pleura and in extrapleural sites.

In this report clinical and pathologic features of seven solitary fibrous tumors of the thyroid gland are presented. Patients' ages ranged from 43 to 64 years (mean 52 years), and tumor sizes varied from 2 to 6 cm. Grossly, the tumors were white–tan and well circumscribed. Microscopically, there was a variegated, wavy, storiform, hemangiopericytic or desmoid-like arrangement of spindle cells. Trapped thyroid follicles within the tumor and peripheral jagged tumor infiltration among follicles were common. There was immunohistochemical reactivity for CD34, CD99, and bcl-2, and ultrastructural analysis of one tumor was consistent with a fibroblastic lineage.

The differential diagnosis included other benign and malignant mesenchymal tumors of the thyroid, spindle cell follicular adenoma, Riedel's thyroiditis, the spindle cell, and paucicellular variants of anaplastic carcinoma, papillary thyroid carcinoma with exuberant nodular fasciitis-like stroma, and the spindle epithelial tumor with thymus-like differentiation. The cumulative data of 13 cases (comprised of the seven present cases and the six previously reported) suggest a benign clinical behavior for thyroid SFT.


Solitary fibrous tumor of the tongue: Report of a case with immunohistochemical and ultrastructural studies.

Wu SL, Vang R, Clubb FJ Jr, Connelly JH.

Department of Pathology and Laboratory Medicine, University of Texas - Houston Medical School; and the Department of Pathology and Laboratory Medicine, St. Lukes Episcopal Hospital, Houston, TX

Ann Diagn Pathol 2002 Jun;6(3):168-71 Abstract quote

Solitary fibrous tumors are rare in extrapleural sites and extremely rare in the oral cavity.

We report a case of a solitary fibrous tumor arising from the tongue of a 70-year-old woman. The tumor measured 1.6 cm in maximum diameter and consists of spindle-shaped cells distributed in a haphazard pattern. Immunohistochemical studies show strong positivity for CD34 and bcl-2, and weak positivity for desmin. Smooth muscle actin and S-100 protein are negative. Electron microscopy shows uniform neoplastic spindle cells with mesenchymal features.

The differential diagnosis for spindle cell neoplasms in the tongue is discussed.



Recurrent solitary fibrous tumor of the pleura with malignant transformation.

Kanthan R, Torkian B.

Department of Pathology, Royal University Hospital, Saskatoon, Saskatchewan, Canada.
Arch Pathol Lab Med. 2004 Apr;128(4):460-2. Abstract quote

Recurrent solitary fibrous tumor of the pleura with malignant progression occurs rarely.

We report a case of solitary fibrous tumor of the pleura in an 85-year-old white woman that recurred 4 times during a span of 10 years and subsequently underwent malignant transformation. The accurate diagnosis of solitary fibrous tumor is aided by ancillary techniques, such as immunohistochemical staining; however, with malignant transformation, such tools may be of limited value.

Long-term clinical follow-up is recommended for all patients with solitary fibrous tumor because of the potential adverse biological behavior of this tumor, which may lead to repeated recurrences and/or malignant transformation.

Myxoid solitary fibrous tumor: a study of seven cases with emphasis on differential diagnosis.

de Saint Aubain Somerhausen N, Rubin BP, Fletcher CD.

Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.

Mod Pathol 1999 May;12(5):463-71 Abstract quote

Focal myxoid change is a well-recognized feature of solitary fibrous tumor (SFT), but to date, predominantly myxoid examples of SFT have not been reported.

We describe seven cases of SFT in which stromal myxoid change affected 50% or more of the tumor examined, thus obscuring typical diagnostic features. Patients ranged in age from 35 to 68 years old (median, 45 yr), with an equal sex distribution. Tumor locations included pleura, orbit, and periparotid subcutaneous tissue, as well as four cases in deep soft tissue (two in the abdominal wall and one each in the chest wall and thigh). Myxoid areas were identified grossly in four cases. Histologically, the lesions were composed of bland spindle cells disposed haphazardly or with a lacy or reticulated appearance in a myxoid, richly vascularized stroma These myxoid areas were punctuated by small cellular aggregates in four cases, and areas showing diagnostic features of SFT were present in five of seven primary excision specimens. Atypical features suggestive of malignancy were not present in any of the cases.

Immunohistochemically, all of the seven cases stained positively for CD34 and CD99 (013), and all were negative for smooth muscle actin, desmin, S-100 protein, epithelial membrane antigen, and pan-keratin. There were no recurrences or metastases reported in four patients with limited follow-up (median duration, 19 mo).

Recognition of this uncommon morphologic subset of SFT is important because of possible confusion, particularly in small biopsy specimens, with a variety of myxoid spindle cell neoplasms with different biologic potential. These include low-grade fibromyxoid sarcoma, myxoid synovial sarcoma, malignant peripheral nerve sheath tumor, low-grade myxofibrosarcoma, myxoid liposarcoma, myxoid spindle cell lipoma, myxoid neurofibroma, and so-called "hemangiopericytoma."

Immunohistochemical expression of beta-catenin in solitary fibrous tumors.

Rakheja D, Molberg KH, Roberts CA, Jaiswal VR.

Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
Arch Pathol Lab Med. 2005 Jun;129(6):776-9. Abstract quote  

CONTEXT: Immunohistochemical staining for beta-catenin may be used as an indicator of the integrity of the Wnt signaling and beta-catenin degradation pathways. Among mesenchymal tumors, aberrant nuclear localization of beta-catenin is seen in desmoid-type fibromatoses but has not been described for solitary fibrous tumors that may mimic the former lesions, especially in small biopsy samples.

OBJECTIVE: To study the immunohistochemical expression of beta-catenin in solitary fibrous tumors.

DESIGN: We performed immunohistochemical staining for beta-catenin in 12 solitary fibrous tumors, one of which showed histologic features of malignancy.

RESULTS: All the tumors showed strong and diffuse reactivity for beta-catenin. Four tumors (33%) showed nuclear staining for beta-catenin, whereas the remaining tumors showed either a membranous or mixed membranous and cytoplasmic pattern of staining. The only histologically malignant tumor of the group showed a mixed membranous and cytoplasmic pattern of staining for beta-catenin.

CONCLUSIONS: Immunohistochemical staining for beta-catenin in solitary fibrous tumors does not show a consistent pattern, which may be due to differences in tumorigenesis. Larger studies with clinical follow-up are required for estimating the impact of the variable staining pattern on clinical behavior of these tumors.



CD34-Reactive Myxoid Dermal Dendrocytoma.

Ohata C, Kawahara K.

Department of Dermatology, Toyonaka Municipal Hospital (C.O.) and Department of Pathology, Osaka National Hospital (K.K.), Osaka, Japan.


Am J Dermatopathol 2002 Feb;24(1):50-3 Abstract quote

Normal skin is composed in part of cells that express CD34. These include periadnexal spindle cells, vascular endothelial cells, and interstitial dendritic cells.

We report on a tumor composed mainly of CD34-reactive spindle cells. A 66-year-old Japanese woman presented with a skin-colored, dome-shaped, cutaneous papule on her left palm that was 7 mm in diameter and had developed within the preceding 3 months. Light microscopic examination showed a well-circumscribed polypoid tumor consisting of spindle-shaped cells and thin collagen fibers arranged loosely in a fascicular pattern within a myxoid matrix. Immunohistochemically, most of the tumor cells stained strongly for CD34, but did not stain with antibodies to S-100 protein, smooth muscle actin, desmin, neuron-specific enolase, epithelial membrane antigen, or factor XIIIa. Staining for vimentin and CD68 was positive.

We believe this lesion to be a CD34-reactive myxoid dermal dendrocytoma of a type that has not been described previously.

Cellular digital fibromas: distinctive CD34-positive lesions that may mimic dermatofibrosarcoma protuberans.

McNiff JM, Subtil A, Cowper SE, Lazova R, Glusac EJ.

Departments of Dermatology and Pathology, Yale University School of Medicine, New Haven, CT, USA.

J Cutan Pathol. 2005 Jul;32(6):413-8. Abstract quote  

Background: Digital fibromas are common benign acral tumors typically reported as angiofibromas (AFs) or acquired digital fibrokeratomas (ADFs). Cellular variants are not well recognized.

Methods: We collected 14 acral fibrocytic lesions showing a spindle cell morphology from our files, and evaluated CD34, Factor XIIIa, epithelial membrane antigen (EMA), and S100 protein staining of these lesions. We compared the histologic and immunohistochemical features of these cellular fibromas with five digital AFs, five ADFs, and five digital dermatofibromas.
Results: The 14 cellular digital fibromas showed intersecting fascicles of thin delicate bland spindle cells in the superficial reticular dermis with a fibrotic-to-slight myxoid stroma. The spindle cells in all cases stained strongly for CD34, and only scattered stromal cells stained for Factor XIIIa. Five tested cases were negative for EMA and S100 protein. The digital AFs, fibrokeratomas, and dermatofibromas stained predominately for Factor XIIIa, with no or minimal staining for CD34.

Conclusions: These findings suggest that a subset of digital fibromas is characterized by a dense cellular proliferation of CD34-positive spindle cells. Awareness of this variant of digital fibroma and its staining pattern is critical in preventing misdiagnosis as dermatofibrosarcoma protuberans, particularly in superficial biopsies.
CD34-positive eruptive fibromas.

Pursley HG, Williford PM, Groben PA, White WL.

Department of Pathology, Bowman Gray School of Medicine/Wake Forest University, Winston-Salem, North Carolina 27157, USA.

J Cutan Pathol. 1998 Feb;25(2):122-5. Abstract quote  

The list of entities comprising a proliferation of CD34 (+) spindle cells continues to grow. Described, herein, is a patient who had an indolent eruption of scattered papules composed of CD34 (+) spindle cells, beginning in adolescence.

An 18-year-old female patient presented with asymptomatic, tan/brown papules over the neck, chest, and proximal extremities. They appeared 6 years previously and had slowly increased in number. Biopsy from the neck showed a proliferation of plump spindle cells, associated with delicate collagen, in the upper reticular dermis. No atypia nor mitotic figures were present. The spindle cells were negative for S-100, muscle actins, and Factor XIIIa, but stained intensely with CD34. This unusual mesenchymal proliferation of CD34 (+) apparent dermal dendrocytes did not have the storiform pattern, short fascicles, nor mitotic figures of DFSP. The completely negative muscle markers helped to exclude dermatomyofibroma, and no morphological evidence of vasoformative differentiation was seen.

The clinical picture militated against solitary fibrous tumor. These eruptive tumors are benign and thought to represent a distinctive fibroma produced by proliferated CD34 (+) stromal cells.



Extrathoracic solitary fibrous tumors: their histological variability and potentially aggressive behavior.

Hasegawa T, Matsuno Y, Shimoda T, Hasegawa F, Sano T, Hirohashi S.

Pathology and Clinical Laboratory Divisions, National Cancer Center Research Institute and Hospital, Tokyo, Japan.

Hum Pathol 1999 Dec;30(12):1464-73 Abstract quote

The histological variability of solitary fibrous tumors may contribute to the difficulty in diagnosing these neoplasms, especially when they arise in extrathoracic sites. Like intrathoracic lesions, the behavior of extrathoracic solitary fibrous tumors is currently unpredictable because these types of tumor have only recently been recognized.

This study therefore was undertaken to examine the clinical behavior and histological, immunohistochemical, and ultrastructural features of 24 extrathoracic solitary fibrous tumors with long-term follow-up. The patients comprised 10 men and 14 women, between 30 and 85 years of age (mean, 51 years). Ten tumors were located in the retroperitoneum or pelvis, 5 in the trunk, 4 in the extremities, 2 in the orbital region, and 1 each in the kidney, uterine cervix, and meninges.

All of the tumors showed a classic morphological appearance, diffuse and strong immunoreactivity for both vimentin and CD34, and variable reactivity for bcl-2. All 7 cases examined ultrastructurally contained fibroblasts and myofibroblasts. Six tumors contained multinucleated giant cells, and in 4 cases these lined pseudovascular spaces with mononuclear cells, thus resembling giant cell angiofibroma and giant cell fibroblastoma. Other potentially similar spindle cell neoplasms mixed with adipose tissue, such as dendritic fibromyxolipoma, lipomatous hemangiopericytoma, cellular angiofibroma, and spindle cell lipoma, were considered in the differential diagnosis. One tumor displayed atypical histological features in the form of increased cellularity and nuclear pleomorphism, but this patient has remained free of disease for 14 years. Another 2 patients developed local recurrences at 6 months and 5 years, and a further patient developed pulmonary metastases that were diagnosed after 7 years. These tumors lacked any atypical histological features in the primary lesions. No patient has so far died of the disease.

In conclusion, most extrathoracic solitary fibrous tumors appear to pursue a benign course, although, because some have the potential to recur or metastasize, careful long-term follow-up is necessary for all patients.

Macpherson and Pincus. Clinical Diagnosis and Management by Laboratory Methods. Twentyfirst Edition. WB Saunders. 2006.
Rosai J. Ackerman's Surgical Pathology. Ninth Edition. Mosby 2004.
Sternberg S. Diagnostic Surgical Pathology. Fourth Edition. Lipincott Williams and Wilkins 2004.
Robbins Pathologic Basis of Disease. Seventh Edition. WB Saunders 2005.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 6th Edition. McGraw-Hill. 2003.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.

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