Solitary Fibrous Tumor with Entrapment of Minor Salivary Gland Tissue: An Unusual Presentation That Requires Exclusion of Pleomorphic Adenoma

Abstract

We report two unusual cases of solitary fibrous tumor (SFT) of minor salivary glands that microscopically mimicked pleomorphic adenoma. One of these lesions presented in the retromolar region and the other in the buccal mucosa. The microscopic features of these two tumors and their intimate relationship with regional mucous minor salivary glands posed a diagnostic challenge. Awareness of the morphological diversity of SFT coupled to a judicious use of appropriate immunohistochemical probes should prove valuable to accurately segregate SFT from pleomorphic adenoma.

Large solitary fibrous tumor of the oral cavity – report of a case

“…SFT and hemangiopericytoma display immunoreactivity for CD34, Bcl-2 and CD99 antigens. Ultrastructural studies have demonstrated pericytic, fibroblastic, and myofibroblastic differentiation in both tumors [3,16]. These findings have led pathologists to consider hemangiopericytoma and SFT as a spectrum of the same entity [22].…”

“…Anti-CD34 antibody, which recognizes a 110-kDa transmembrane cell surface glycoprotein found on myeloid progenitor cells, is the most consistent and reliable immunohistochemical marker for SFT [14][15][16]. On the other hand, neoplastic cells are negative for cytokeratins, S-100 protein, epithelial membrane antigen, smooth muscle actin, and Factor VIII [13,17].…”

“…Given the wide range of morphology, SFT can potentially be mistaken for other benign and malignant soft tissue tumors [7,12,14,16]. The differential diagnosis of benign SFT involving the oral cavity includes a variety of lesions, especially fibrous histiocytoma, schwannoma, and, most importantly, hemangiopericytoma [14,17].…”

Two New Localizations of Solitary Fibrous Tumor in the Italian Population: Parotid Gland and Oral Cavity—Review of the Literature

“…Only 70 cases have been described in the English-language literature. 26 The buccal mucosa is the most common site of occurrence, followed by the tongue, gingiva, palate, lip, buccal sulcus, posterior trigone, and mental region (Table 2). 17,22,27 In the Italian literature, only 2 cases of SFT of the infratemporal fossa, 4 1 case in the laterocervical spaces, 28 and 1 case in the parapharyngeal space 8 have been described.…”

“…[22][23][24][25][26][27]29,30 Diagnosis of SFT can only be performed by histologic examination, because clinical signs and radiologic features are not specific enough. The tumor microscopic aspect shows spindle or ovoid cells associated with collagenous matrix and branched vessels with a hyaline wall.…”