Large congenital melanocytic nevus

A rare skin hamartoma characterized by at least one pigmented skin lesion present at birth of more than 20 cm (large congenital melanocytic nevus; LCMN) or 40 cm (giant; GCMN) projected adult diameter. The primary lesion is composed of mutated melanocytes and often locally disorganized epidermal annexes or dermis, and presents with an elevated risk of malignant transformation to melanoma or, more rarely, other neoplasms in skin or central nervous system.