Focal dermal hypoplasia. Current concepts and differential diagnosis.

Focal dermal hypoplasia syndrome (FDH) is a congenital disorder of mesodermal derivation with some ectodermal participation. The disorder, first described in 1962, is characterized by tenacious defects consisting of thinning of the skin; herniations of adipose tissue; abnormal skin pigmentation and other skeletal, dental, ocular, hair, and nail abnormalities. A rare instance of focal dermal hypoplasia syndrome is reported as characterized by papillary gingival hyperplasia. Differential diagnostic guidelines that separate focal dermal hypoplasia from a host of other skin and mucous membrane disorders are discussed along with therapeutic modalities and the possible relationship of human papillomavirus to focal dermal hypoplasia syndrome.