The objective was to investigate two cases of solitary fibrous tumor (SFT) of oral mucosa, emphasizing the differential diagnosis with one case of oral hemangiopericytoma (HPC), in terms of their morphological and immunohistochemical features. Solitary fibrous tumors showed cellularity and collagenization varying from area to area, focal perivascular hyalinization, scattered giant nuclei cells and abundant mast cells throughout the tumor. The hemangiopericytoma case exhibited thin-walled and dilated vessels lined with flat endothelial cells, identified by "staghorn appearance". Tumoral cells of solitary fibrous tumor exhibited immunohistochemical positivity for CD34, as well as endothelial cells. The hemangiopericytoma was positive only in endothelial cells. In solitary fibrous tumor, alpha-smooth muscle actin, h-caldesmon and laminin stained the wall vessels. In hemangiopericytoma, on the other hand, the wall vessels were positive only for laminin, which staining was also observed in perivascular tumoral cells. The morphological and immunohistochemical differences observed allowed us to infer these lesions constitute distinct entities.
"Ultrastructural studies have demonstrated pericytic, fibroblastic, and myofibroblastic differentiation in both tumors  . These findings have led pathologists to consider hemangiopericytoma and SFT as a spectrum of the same entity . Even when strict morphologic criteria are adopted and appropriate immunostains employed, the diagnosis of SFT remains difficult, especially at extrapleural sites, due to extreme intratumoral variability and close similarity of single parts of individual tumors with prognostically different benign and malignant soft tissue neoplasms . "
"It was initially described in the pleura of middle-aged adults but other sites may be involved, including the oral cavity, and occasionally affect children and adolescents [1–20]. SFT of the oral cavity presents as a slow-growing and painless submucosal well delimitated mass, usually involving the buccal mucosa and tongue of patients in their sixth decade of life         . "
[Show abstract][Hide abstract] ABSTRACT: Solitary fibrous tumor (SFT) is uncommon in the oral cavity, and there are no reports in children. We report a case of a large SFT affecting the upper lip of a one year-old boy. The tumor was characterized by proliferation of spindle and multinucleated stellate-shaped cells that were intermingled between thin and thick collagen fibers. The tumor cells were diffusely positive for CD34, Bcl-2, CD99, and negative for specific muscle actin, smooth muscle actin, calponin, and caldesmon. Ki-67 labeling was less than 1%. The patient remains well after tumor excision.
International Journal of Pediatric Otorhinolaryngology Extra 09/2014; 9(3). DOI:10.1016/j.pedex.2014.03.006
"The demonstration of mast cells in SFTs has been reported previously [18, 36, 30]; we noted mast cells in 38% of our cases. However, mast cells are a feature of other soft tissue lesions including schwannomas , spindle cell lipomas , neurofibromas  and vascular tumors . "
[Show abstract][Hide abstract] ABSTRACT: We describe clinical, morphologic, and immunohistochemical features of 21 cases of solitary fibrous tumor presenting in the oral cavity. There were 9 male and 12 female patients with a median age of 51 years (range 37-83). The most common locations included the buccal mucosa (the most common site), lip, maxillary or mandibular vestibule and tongue. Histopathologic examination showed well-circumscribed tumors with two well-defined patterns: the classic pattern with densely cellular areas alternating with hypocellular areas in a variably collagenous, vascular stroma and a more uniformly sclerotic pattern with only subtle classic areas. The spindle-shaped neoplastic cells consistently showed immunoreactivity for antibodies directed against CD34. Five of nineteen cases (26%) were reactive for CD99 and 19 of 19 for Bcl-2. Follow-up information was available in 17 cases and averaged 54 months, with no evidence of recurrence or metastasis in any of these patients. Awareness that solitary fibrous tumor may present in the oral cavity is important so that confusion with other spindle cell neoplasms can be avoided. We also briefly describe the differential diagnosis and compare this series, the largest single series of intraoral SFT, to cases previously reported in the literature.
Head and Neck Pathology 07/2009; 3(2):106-15. DOI:10.1007/s12105-009-0111-8
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