trichoepithelioma

Trichoepithelioma is a benign adnexal skin tumor that shows differentiation toward hair follicle germinative structures. It most often presents as small, skin-colored to translucent papules or nodules on the face, particularly the nose, cheeks, or periocular area. Solitary lesions are common, but multiple lesions can occur in familial conditions such as Brooke-Spiegler syndrome, which involves autosomal dominant inheritance.

Clinical features vary from a single, slow-growing nodule to multiple lesions that may be cosmetically troubling. Lesions are typically indolent and asymptomatic. In the facial region, cosmetic concern is often the primary reason for treatment. There is no malignant potential in sporadic cases, though rare cases of transformation into basal cell carcinoma have been reported in the literature.

Histologically, trichoepithelioma shows nests and cords of basaloid cells with peripheral palisading, primitive follicular structures, and multiple horn cysts set in a fibrous stroma. The pattern resembles hair germ differentiation. These features help distinguish trichoepithelioma from basal cell carcinoma, which may lack horn cysts and tend to show more infiltrative growth and mitotic activity.

Diagnosis is based on clinical appearance supported by histopathology when tissue is obtained. Genetic forms, such as Brooke-Spiegler syndrome, are associated with CYLD gene mutations.

Management focuses on cosmetic improvement. Solitary lesions are commonly treated with surgical excision or Mohs micrographic surgery for facial lesions; alternatives include CO2 laser, dermabrasion, or punch excision. Recurrence can occur with incomplete removal. Overall prognosis is excellent, with benign behavior and rare malignant transformation.