Preauricular skin defects. A consequence of a persistent ectodermal groove

The term aplasia cutis is used to describe congenital localized defects of the skin. This affliction is the end result of various in utero events. Aplasia cutis of the face, although rare, has been associated with numerous dysmorphic features and described under many clinical terms.

We studied 10 patients with oval, atrophic patches distributed in a linear pattern on the preauricular region of the face. Most of the defects were bilateral, and all consistently fell in an oblique line extending from the preauricular region to the angle of the mouth. This line corresponds to the region of fusion between the maxillary and mandibular facial prominences during embryonic development.

This type of facial aplasia cutis may be the result of incomplete fusion of the ectodermal groove between the maxillary and mandibular facial prominences. Although other types of facial skin defects may share a similar pathogenic mechanism, they are distinct in that they occur in different regions and may have other abnormal facial features.