Trichilemmoma

**Semantic type:** Neoplastic Process

**Definition:** A benign neoplasm arising from the outer hair sheath and infundibulum. It occurs in the head and neck, usually on the face. It usually presents as an exophytic wart-like lesion or a dome-shaped lesion with a smooth surface. Morphologically, it is characterized by the proliferation of cuboidal cells with clear or eosinophilic cytoplasm in the dermis with connection to the epidermis/hair follicle. There is peripheral cellular palisading, and the lesion is surrounded by a hyaline band.

**Synonyms:** - TRICHOLEMMOMA, BENIGN - Tricholemmoma