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

ArticleinHuman Pathlogy 26(4):440-9 · May 1995with20 Reads
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.
    • "Nuclear labeling for STAT6 is highly specific for SFT and is related to the NAB2-STAT6 gene fusion [11]. Most of these lesions have a benign course, but local recurrence and metastasis have been reported in a number of cases [12]. In terms of malignant potential, pleural SFTs are Competing Interests: The authors have declared that no competing interests exist. "
    [Show abstract] [Hide abstract] ABSTRACT: Solitary fibrous tumors (SFTs) of the spine are exceedingly rare tumors of mesenchymal origin. Most spinal SFTs arise from the thoracic spine, followed by cervical spine, and last lumbar spine with only 6 cases reported in literature. SFTs represent a wide range of neoplasms, ranging from benign to malignant. These tumors can develop a late recurrence, even after a decade or more of initial presentation, requiring long-term follow-up. We present a case of recurrent SFT of the lumbar spine with vertebral body involvement, presenting more than a decade after initial resection. It was initially misdiagnosed as a paraganglioma. To the best of our knowledge, there have been only 3 previous cases reporting SFT with vertebral body involvement.
    Full-text · Article · Sep 2016
    • "Thus, histologically, SFT can be confused with a variety of other soft tissue tumors, such as hemangiopericytoma and Schwannoma. Immunohistochemically, SFT can be differentiated from these tumors by their strong positivity for CD34 and vimentin, while being negative for CD31, cytokeratin, desmin, and the S-100 protein (4). "
    [Show abstract] [Hide abstract] ABSTRACT: Solitary fibrous tumor (SFT) is a well-known tumor composed of spindle cells found most commonly in the pleura. Recently, accounts of their rare occurrence at other sites, including the head and neck area, have been reported. The parapharyngeal space is a rare location even for head and neck SFTs, and thus, could be confused with a variety of other tumors that can originate in this area. Here, we report a case of SFT originating from the post-styloid parapharyngeal space and discuss the possible differential diagnosis on radiographic findings.
    Full-text · Article · Jul 2014
    • "[4] However, its expression can be lost in high‑grade tumors or tumors with repeated recurrence. [7] SFT may present with malignant behavior and local recurrence or metastasis. Pathological criteria for malignant SFT is based on high cellularity, >4 mitotic figures/10 hpf and hemorrhage/necrosis. [8] Local recurrence is defined as tumor involving the tumor bed or a scar of a previous surgery. "
    [Show abstract] [Hide abstract] ABSTRACT: Solitary fibrous tumor (SFT) represents a spectrum of mesenchymal tumors, encompassing tumors previously termed hemangiopericytoma, as having intermediate biological potential. Though they can occur at any site, lower distal extremity is a rare site and recurrence in it is extremely rare. Behavior of SFT is unpredictable. Histomorphology and clinical follow-up have poor correlation. The most important single indicator of clinical outcome is complete excision of the tumor at the time of primary presentation. Tumors with positive margins require close follow-up for several years owing to the potential for late local recurrence.
    Full-text · Article · Jul 2014
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