Membranous aplasia cutis congenita

Aplasia cutis congenita (ACC) is a rare congenital malformation characterized by the focal absence of skin visible at birth, most frequently involving the scalp, although any part of the body may be affected. The estimated incidence is approximately 1 to 3 per 10,000 live births. The pathogenesis is heterogeneous and yet not fully understood. Proposed etiologies include genetic factors, teratogenic insult exposure, vascular disruptions, and mechanical trauma in utero. Clinically, ACC presents with variable morphology. The most frequent presentation is a well-demarcated area of ulceration or atrophic scarring on the scalp. ACC can rarely manifest as a bullous or membranous lesion with a cystic, translucent appearance, occasionally associated with deeper tissue involvement.