Solitary fibrous tumor: Histologic and immunohistochemical spectrum of benign variants presenting at different sites

Department of Pathology and Cell Biology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA 19107, USA.
Human Pathlogy (Impact Factor: 2.81). 05/1995; 26(4):440-9. DOI: 10.1016/0046-8177(95)90147-7
Source: PubMed

ABSTRACT Twenty-nine tumors (from 26 patients, including two with recurrent disease) diagnosed as solitary fibrous tumor (SFT) of the pleura (n = 23), mediastinum (n = 4), abdominal cavity (n = 1), and parotid gland (n = 1) were studied immunohistochemically. Three histologically malignant tumors showed areas of high cellularity and mitotic activity (more than 4 mitoses/10 high-power fields) with features resembling malignant fibrous histiocytoma, malignant hemangiopericytoma, or fibrosarcoma, together with areas typical of benign solitary fibrous tumor. Formaldehyde-fixed, paraffin-embedded tissues and avidin-biotin-complex immunostaining were used. All of the tumors showed vimentin positivity and did not stain for cytokeratin, glial fibrillary acidic protein, or muscle cell markers, except for focal desmin reactivity in seven tumors, mostly seen in frozen sections, and focal keratin reactivity in one histologically malignant tumor. The neoplastic cells were positive for CD34 and negative for CD31; these patterns also were seen in the three histologically malignant cases. In nine of the cases acetone-fixed frozen sections showed variable focal positivity for neurofilament proteins of 68 kd. We conclude that SFT is a neoplasm of fibroblasts/primitive mesenchymal cells with features of multidirectional differentiation. We also report the finding of a novel site for SFT, the parotid gland.

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    • "13—23% of cases [1] [3] . High cellularity, increased mitotic activity (more than 4 mitoses per 10 high-power fields), pleomorphism and haemorrhage are the factors favouring malignancy [1] . "
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    • "Localized fibrous tumors of the pleura (LFTP) represent a rarely encountered clinical entity [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]. After several decades of controversies, it is nowadays recognized that they originate from mesenchimal cells of submesothelial tissue of the pleura [1] [2] [4]. It is recognized that surgery represents the treatment of choice of these tumors [1] [2] [5] [11]. "
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