aplasia cutis congenita

[kyōōtĭs kən-jĕnĭ-tə]
n.
  1. The congenital absence or deficiency of a localized area of skin, usually on the scalp, with the base of the defect covered by a thin translucent membrane.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.