Focal dermal hypoplasia (FDH) is a rare ectomesodermal dysplasia syndrome characterized by cutaneous, skeletal, dental, ocular, and soft-tissue defects. An X-linked dominance with death of male subjects has been assumed as the mode of inheritance. Only a few cases of FDH have been reported in male subjects. A 68-year-old man had typical skin lesions of FDH. Clinical, histologic, and immunohistochemical features are presented.
The cutaneous abnormalities consisted of atrophic hyperpigmented and hypopigmented macules and erythematous, slightly raised lesions showing a highly characteristic linear distribution. Other abnormalities, including syndactyly, apocrine hidrocystoma of eyelids, and bilateral cholesteatoma were observed. Only one case of FDH in association with an apocrine hidrocystoma has been reported previously. Consistent findings microscopically in the erythematous lesions were areas of scar formation with subepidermal bulla overlying the neodermis. A strongly positive immunohistochemical reaction for vimentin, fibronectin, and collagen type III was observed in the scar tissue. No collagen type IV was detected in the basement membrane zone of the epidermis covering the lesion.
It has been proposed that fibroblastic abnormalities may lead to an alteration of collagen synthesis in FDH, although confirmation of this hypothesis was unavailable. Our findings suggest that production of collagen type IV may be delayed in FDH resulting from a fibroblastic defect.(Arch Dermatol. 1992;128:1078-1082)