Desmoplastic Fibroblastoma (Collagenous Fibroma)

Abstract

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