Desmoplastic fibroblastoma (collagenous fibroma) - Case report and review of the literature

We report a case of desmoplastic fibroblastoma/collagenous fibroma in a 42- year-old African-American male. The 10 cm tumor mass was located subcutaneo usly on the right lower back. Grossly, the tumor was firm and well-circumsc ribed and, on cut surface, had a white and homogeneous appearance. Microsco pically, the tumor was composed of medium-sized spindled and stellate fibro blasts sparsely distributed in a densely fibrous background. No significant nuclear pleomorphism, mitotic figures, or necrosis were identified. The tu mor cells were diffusely positive for vimentin and factor XIIIa but were ne gative for all other markers tested. Ultrastructurally, the tumor cells had features of fibroblasts with abundant rough endoplasmic reticulum. No recu rrence has been seen at 5 months after excision.