Three patients having a remarkable congenital decrease in the connective tissues of the skin have been reported under the title of focal dermal hypoplasia. This defect appears as linear areas of thinning of the skin and herniations of adipose tissue in the form of yellowish papules. This anomaly seems always to be accompanied by a number of other defects of ectodermal and mesodermal tissues and may represent only one part of a syndrome.
The relationships of this syndrome to congenital poikiloderma of Thomson's type, to nevus lipomatosus cutaneous superficialis, and to a number of other congenital cutaneous defects have been discussed. It is concluded that because of clinical and microscopic differences the syndrome characterized by focal dermal hypoplasia is separate from these other conditions.
GOLTZ RW, PETERSON WC, GORLIN RJ, RAVITS HG. Focal Dermal Hypoplasia. Arch Dermatol. 1962;86(6):708-717. doi:10.1001/archderm.1962.01590120006002