INTRAORAL PIGMENTED BENIGN FIBROUS HISTIOCYTOMA: AN UNUSUAL PRESENTATION

Abstract

Benign fibrous histiocytoma (BFH) is a benign mesenchymal neoplasm that shows both fibroblastic and histiocytic differentiation. To date, about 65 oral BFH cases have been reported. Oral BFH most often affects middle-aged adults, with a female predilection. Several variants of BFH have been described, such as classical, aneurysmal, hemosiderotic, cellular, epithelioid, lipidized, clear cell, granular cell, myxoid, and signet-ring cell. A 56-year-old woman was referred for management of a painless lesion in the palate 6 years ago. After excisional biopsy, microscopic analysis showed a benign proliferation of spindle cells, arranged in a storiform pattern, associated with pigmented deposits, which were highlighted with Fontana-Masson and Perl's iron stains. Immunohistochemical analysis revealed positivity for vimentin, HLA-DR, CD68, CD163 and FXIIIa; pan-CK, EMA, α-SMA, GFAP, S-100, and CD34 were negative. Ki-67 highlighted scarce positive cells. The current case probably expands the microscopical spectrum of the hemosiderotic variant of BFH. Benign fibrous histiocytoma (BFH) is a benign mesenchymal neoplasm that shows both fibroblastic and histiocytic differentiation. To date, about 65 oral BFH cases have been reported. Oral BFH most often affects middle-aged adults, with a female predilection. Several variants of BFH have been described, such as classical, aneurysmal, hemosiderotic, cellular, epithelioid, lipidized, clear cell, granular cell, myxoid, and signet-ring cell. A 56-year-old woman was referred for management of a painless lesion in the palate 6 years ago. After excisional biopsy, microscopic analysis showed a benign proliferation of spindle cells, arranged in a storiform pattern, associated with pigmented deposits, which were highlighted with Fontana-Masson and Perl's iron stains. Immunohistochemical analysis revealed positivity for vimentin, HLA-DR, CD68, CD163 and FXIIIa; pan-CK, EMA, α-SMA, GFAP, S-100, and CD34 were negative. Ki-67 highlighted scarce positive cells. The current case probably expands the microscopical spectrum of the hemosiderotic variant of BFH.