A case of membranous aplasia cutis congenita and dermoscopic features

Membranous, bullous, or cystic aplasia cutis congenita is a clinical subtype of aplasia cutis, covered with a membranous or glistening surface. A male newborn presented at birth with two flat lesions on the left parietal scalp, surrounded by a rim of terminal hairs. Physical examination revealed two translucent papules. On dermoscopy, they showed a reddish background, thin, lineal vessels and, remarkably few hair bulbs could be seen because of the translucency of the lesion. No skull bone and brain defects were found. The diagnosis of membranous aplasia cutis congenita was established. Histologically, it is characterized by an atrophic epidermis with loose fibrovascular stroma and edematous dermal stroma. Dermoscopy may help to rule out other entities (herpes simplex, epidermolysis bullosa, trauma…) since the atrophic epidermis and fibrovascular stroma is evidenced by the hair bulbs and its characteristic translucency ("translucency's sign").