Focal dermal hypoplasia syndrome. An electron microscopical study of the skin lesions

An 11-month-old female with focal dermal hypoplasia syndrome is described. Histologically, the skin lesions were characterized by a marked decrease in dermal connective tissue. Ultrastructurally, there were a number of fine filamentous structures measuring 5 to 70 nm within and between the bundles of collagen; most of the dermal fibroblasts of the lesions possessed no remarkably developed rough endoplasmic reticulum and Golgi complex. Multilocular fat cells which are regarded as young fat cells were often seen. It is suggested that this disease may be characterized by a decreased rate of collagen synthesis by fibroblasts and an overgrowth of adipose tissue.