Aplasia cutis congenita

Aplasia cutis congenita is a rare disorder in which a baby is born with an area of skin missing. The scalp is the most commonly affected site, with lesser involvement of the trunk and limbs, and the condition is described as the most common congenital scarring alopecia, a focal absence of the epidermis that may or may not also involve deeper skin layers. In 1986 Ilona J. Frieden sorted it into nine groups according to where the lesions lie and which other congenital anomalies accompany them; her type 5 covers truncal lesions with fetus papyraceus, showing a symmetrical star-shaped or butterfly-shaped absence of skin, with or without involvement of the proximal limbs. The cause remains unclear. Proposed contributors include intrauterine varicella or herpes infection, drugs such as methimazole, carbimazole, misoprostol, valproate, cocaine and marijuana, fetus papyraceus, feto-fetal transfusion, vascular coagulation defects, amniotic membrane adherence, abnormal mechanical forces on elastic fibres, and trauma. It can occur alongside Johanson-Blizzard syndrome, Adams-Oliver syndrome, trisomy 13 and Wolf-Hirschhorn syndrome, and has been linked to Peptidase D haploinsufficiency and a deletion in chromosome 19.