Abstract

Panfolliculoma with sebaceous differentiation is a rare entity with only one published case report. We report a second case presenting in a 57 year old male on the scalp. The patient reported a one year history of a growing scalp lesion. He was referred to a general surgeon for excision of what clinically was felt to be a sebaceous cyst measuring 10 x 10 mm. On piecemeal excision, the tumor consisted of variably sized solid and solid-cystic aggregates, with connection to the epidermis. There were areas of germinative cells, infundibular, isthmic, matrical, inner and outer root sheath differentiation, consistent with a diagnosis of panfolliculoma – a benign neoplasm that recapitulates all portions of the hair follicle. Notably, there were multiple foci of sebaceous differentiation ranging from single admixed cells to larger discrete nests of mature sebocytes. Panfolliculoma is a rare, benign follicular neoplasm. They typically present on the head and neck as a nodule with a clinical differential that often includes cyst or basal cell carcinoma. Panfolliculoma with sebaceous differentiation is thought to represent multilineage differentiation within the folliculosebaceous-apocrine unit, a known occurrence in adnexal tumors. The primary pathological differential diagnosis is trichofolliculoma, which also shows various aspects of follicular differentiation and often features a sebaceous component. The two entities can be distinguished by the presence of a central dilated follicular structure in trichofolliculoma.

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