Solitary fibrous tumor of the thigh with epithelioid features: A case report

Department of Pathology, Hospital General Universitario, Valencia, Spain.
Diagnostic Pathology (Impact Factor: 2.6). 02/2007; 2(1, article 19):19. DOI: 10.1186/1746-1596-2-19
Source: PubMed


Extrapleural Solitary Fibrous tumors (SFTs) have been increasingly reported. The retroperitoneum, deep soft tissues of proximal extremities, abdominal cavity, trunk, head and neck are the most common extraserosal locations reported. Microscopically they show a wide range of morphological features, and so the differential diagnosis is extensive. Immunohistochemically, they commonly express CD34, vimentin, bcl-2 and CD99. Epithelial membrane antigen (EMA) and smooth muscle actin (SMA) may occasionally be expressed. Epithelioid morphology in extrapleural SFT has only very occasionally been described (five cases reported), some of them with biphasic pattern and others with malignant characteristics.
A SFT of the thigh with epithelioid areas in a 63 year old woman is reported. Microscopically the tumor showed areas hypo and hipercellular. At the periphery of the hipercellular areas there were nodules composed of epithelioid cells. Immunohistochemically both the spindle and epithelioid cells were positive for CD34, vimentin, bcl-2 and CD99. Epithelial, neural and muscular markers were negative. Molecular study was done and ruled out a synovial sarcoma.
Ten cases of SFT of the thigh have been reported but to our knowledge this is the first case with epithelioid morphology affecting the extremities. Identification of this pattern of SFT is of importance, to avoid misdiagnosis with other more aggressive conditions in soft tissue.

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    • "In addition, the neoplasms display varied expression of desmin (89%, 8/9), CD30 (71%, 5/7), SMA (50%, 4/8), and cytokeratin (25%, 2/8), while EMA, S100, CD117, Myf4, myogenin, caldesmin, and HMB45 expression is consistently negative. Therefore, IMT-RAs could be easily distinguished from poorly differentiated carcinoma, malignant melanoma, epithelioid gastrointestinal stromal tumor, epithelioid solitary fibrous tumor [17], myofibroma [18] and alveolar rhabdomyosarcoma. It is noteworthy that a few mesenchymal mimics listed below may also show cytoplasmic ALK staining [19] and thus should particularly be discriminated to avoid misdiagnosis. "
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    ABSTRACT: Inflammatory myofibroblastic tumors (IMTs) are categorized as intermediate biologic neoplasms, whereas IMTs with genetic features of ran-binding protein 2 (RANBP2) and anaplastic lymphoma kinase (ALK) rearrangement (IMT-RAs) are possibly related to a more aggressive clinical course. However, fewer than 10 cases of IMT-RA have been reported to date. Herein, we present 2 new cases of IMT-RA in which both tumors recurred quickly after primary surgery; one patient died 3 months later from the disease, and the other patient has been living with the disease for 12 months. IMT-RAs are characterized by noncohesive epithelioid and rounded tumoral cell morphology, commonly derived from pelvic and peritoneal cavities, and frequently show larger tumor sizes. The relation between the clinicopathologic features and poor prognosis of IMT-RA is discussed. Virtual slides The virtual slide(s) for this article can be found here:
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    • "For example, pleomorphic lipoma can be misdiagnosed as a nonlipomatous tumor such as myxofibrosarcoma if the tumor lacks mature fat component [8]. Similarly, solitary fibrous tumor is one of the tumors which can show a wide range of morphologic features [9]. Particularly, if solitary fibrous tumor shows epithelioid growth pattern, other tumors having epithelioid features such as epithelioid sarcoma or synovial sarcoma should be excluded. "
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    ABSTRACT: A 58-year-old woman presented with a solitary myofibroma that arose in the sigmoid colon. Computed tomography revealed a highly enhanced intramural mass (1.3-cm maximum diameter) in the proximal sigmoid colon. Histologically, the tumor exhibited a biphasic growth pattern, which comprised haphazardly arranged, interwoven fascicles of plump, myoid-appearing spindle cells with elongated nuclei and abundant eosinophilic cytoplasm, and more cellular areas of primitive-appearing polygonal cells that were arranged in a hemangiopericytomatous pattern. The tumor cells were positive for smooth muscle actin (SMA), and negative for desmin, h-caldesmon, CD34, cytokeratin, S100 protein, and CD117. The Ki-67 labeling index was not high (up to 7%). Based on these histologic and immunohistochemical features, our patient was diagnosed with a myofibroma of the sigmoid colon. The presence of solitary myofibroma in the intestine of an adult requires attention to avoid misdiagnosis as a more aggressive mesenchymal tumor. Virtual Slides The virtual silde(s) for this article can be found here:
    Full-text · Article · Jun 2013 · Diagnostic Pathology
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    • "Even though SFTs are predominantly regarded as rare pleural neoplasms, a wide spectrum of extrathoracic sites has been reported, such as the head and neck regions [8-10], the abdomen, retroperitoneum and pelvis [11-17] and the soft tissues of the extremities [18-33]. Extrathoracic SFTs are rare and account for approximately 0, 6% of all soft tissue tumors [30-32]. Like their pleural counterparts, extrathoracic SFTs usually behave in a benign fashion but in approximately 10% of cases recur locally or metastasize [22,24]. "
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    ABSTRACT: Purpose To describe the imaging features of soft tissue solitary fibrous tumors, with histopathological correlations and clinical outcome. Material and methods Twenty-seven patients with histologically proven SFTs were retrospectively evaluated. Imaging studies included six radiographs, five U/S studies, eighteen CT scans, fourteen MRI exams, and one angiography. Results On CT scans, two lesions were isodense and five were mildly hypodense compared to muscle while 11 lesions appeared heterogeneous-mixed of iso and hypodense areas. Heterogeneous enhancement was depicted in 13 lesions and four lesions enhanced homogeneously. Six lesions were partially calcified. On T1W MR images, seven lesions were isointense and one was slightly hyperintense relative to adjacent muscles while five lesions appeared heterogeneous-mixed of iso and hypointense areas. T2W images showed high SI in two cases and heterogeneous-mixed in seven cases. Enhancement was heterogeneous in six and homogeneous in four lesions. Patchy unenhanced areas (on CT and T1W MR images) along with patchy areas of low to markedly high SI on T2W images were depicted in 19 lesions. The enhanced portions correlated to areas of increased vascularity and cellularity. The four clinically more aggressive lesions could not be predicted on imaging. Conclusion Typical soft tissue SFTs are deep masses made of isodense and isointense areas relative to adjacent muscles mixed with hypodense and hypointense areas on unenhanced CT and MR T1W respectively. Variable enhancement patterns and mixed to high signal intensities on MRT2W are attributed to tumor’s cellularity, vascularity, collagen distribution and/or degeneration. Heterogeneity of SFTs affects imaging features on MRI and CT modalities. The biological behavior of soft tissue SFTs can not be predicted based solely either on histopathologic or imaging evaluation.
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