Basaloid Follicular Hamartoma: A Case Report and a Novel Cosmetic Treatment.

Introduction: Basaloid follicular hamartoma (BFH) is a rare, benign neoplasm of the hair follicle, characterized by multiple brown papules involving the face, scalp, and trunk. It is described by multiple clinical forms, and can present as localized or generalized. Diagnosis is made histologically via biopsy, which is important in order to distinguish BFH from basal cell carcinoma (BCC) or other malignant epithelial neoplasms. Correct diagnosis allows for the avoidance of unnecessary surgeries to remove benign lesions. While benign, lesions can be cosmetically unacceptable. Case Report: A 68-year-old man with a two-year history of brown, homogenous papules on his face presented to discuss treatment options. A physical examination revealed hundreds of dark brown, 1- to 3mm verrucous papules distributed throughout the face. Two punch biopsies revealed histologic features consistent with BFH. Discussion: BFHs classically present with multiple 1- to 2mm tan-to-brown-colored papules distributed on the face, scalp, neck, axilla, trunk, and pubic area. Differential diagnoses can include nevus sebaceous, lichen striatus, linear epidermal nevus, and basal cell nevus. BFH arises from a mutation in the patch gene, the same gene thought to cause nevoid BCC syndrome. Histologic examination of BFH lesions is essential to diagnosis. No standard of care exists for BFH; treatment options remain limited. This patient was treated with three rounds of pulsed dye laser (PDL) therapy and showed marked improvement in the treated areas. The authors propose PDL to be a safe, effective, and novel cosmetic treatment for BFH and potentially other adnexal tumors.