Solitary asymptomatic lobular perianal nodule on an infant.

Folliculosebaceous cystic hamartoma (FSCH) is a benign lesion that presents as a solitary papule or nodule that typically affects the face and scalp of adults. A few reports have observed a congenital presentation. We present an infant boy exhibiting a tumor with overlap features between an FSCH and fibrofolliculoma in the perianal region that was first noticed at 6 months of age. The histological examination showed a hamartomatous benign proliferation of hair follicles and disordered sebaceous glands, which is consistent with the infundibular structures and radiating sebaceous glands that are typically observed in previously reported cases of FSCH. Sebaceous differentiation is a hallmark feature of FSCH. Folliculosebaceous cystic hamartoma is believed to be a late-stage form of trichofolliculoma (TF). Another consideration is that FSCH and TF are two distinct entities set apart by their degree of sebaceous or follicular differentiation and development of the mesenchymal stroma.