Holoprosencephaly presenting as membranous aplasia cutis and diabetes insipidus: report of one case.

Membranous aplasia cutis is characterized by the presence of a cystic-like nodule located at the midline of the scalp, which is surrounded by a ring of long, dark hair, called a 'hair collar' sign; it always contributes to underlying central nervous malformation. Herein, we report a 2-month-old male infant who was admitted to our ward due to diabetes insipidus complicated with hypernatremia. Physical examination revealed the unique 'hair collar' sign, which is a rare presentation of congenital aplasia cutis. Imaging study revealed holoprosencephaly. Thus, the aim of this report is to remind pediatrician that in a neonate who has "membranous aplasia cutis" with hair collar sign, imaging studies, including brain sonography, computed tomography or magnetic resonance imaging of the brain, should be performed because of the great possibility of underlying central nervous system malformation.