GIANT TRICHOBLASTOMA ON THE SCALP

We describe a case of giant trichoblastoma that had been present for m any years on the scalp of a 69-year-old man. The specimen was examined histopathologically, immunohistochemically, and ultrastructurally. Hi stopathologic examination showed that neoplastic cells were arranged i n different patterns from area to area, including rippled, adenoid, an d palisading patterns. In some areas of the neoplasm, foci of sebaceou s differentiation were also present. The ultrastructural characteristi cs of neoplastic cells support the notion that trichoblastomas are neo plasms composed mostly of follicular germinative cells.