A case of tumor of the follicular infundibulum with sebaceous differentiation.

Tumor of the follicular infundibulum (TFI) is an uncommon benign adnexal tumor that usually presents as a solitary keratotic papule on the face or scalp of elderly patients. Histopathologically, it typically manifests as a plate-like fenestrated proliferation of monomorphic pale-staining cells. A 76-year-old male presented with about a 2 cm, well-defined, yellowish to brownish, slightly elevated, twisted and bent, interrupted, cord-like plaque on his left lower abdomen. Microscopic examination revealed a sharply demarcated plate-like proliferation of pale cells localized in the papillary dermis with multiple connections to the overlying epidermis. The histopathological features were compatible with TFI, except for foci of sebaceous differentiation. There has been one previous case report of TFI with sebaceous differentiation in the English medical literature. Herein, we report on a singular case of TFI with sebaceous differentiation.