PILAR SHEATH

 

ACANTHOMA

 

Middle-aged and elderly individuals are commonly

affected. Pilar sheath acanthoma is characterized by a small (5 to 10 mm in diameter), solitary, skin-colored papule situated on the head and neck, particularly around the upper lip. A central, occasionally keratin plugged pore is often present. Histologically, there is a crateriform depression in the epidermis representing a widely dilated, keratin-filled infundibulum or closely set infundibula contiguous at the base with numerous epithelial lobules of pink keratinocytes. The epithelial lobules radiate into the dermis, sometimes with involvement of the subcutis. They are surrounded by a narrow rim of fibrous tissue. The epithelium shows similar features to those of the isthmus of a normal hair follicle. Small infundibulocystic structures, tubular structures, and foci of sebaceous differentiation (ducts or sebaceous lobules) are variably observed in individual cases. Treatment is surgical excision