Progressive symmetric erythrokeratodermia. Histological and ultrastructural study of patient before and after treatment with etretinate.

Progressive symmetric erythrokeratodermia is a rare inherited cornification disorder characterized by symmetric erythematous hyperkeratotic plaques. Approximately 25 cases have been reported, but the ultrastructural features have not been well characterized. In this article, we describe the clinical, histologic, and ultrastructural findings noted in our patient. Biopsy specimens taken before treatment with etretinate showed hyperkeratosis with a well-preserved granular layer and acanthosis. Ultrastructural examination disclosed that granular cells contained markedly swollen mitochondria and that corneocytes contained many lipidlike vacuoles. After initiation of treatment, considerable clinical improvement was observed, but without significant histologic modification. The principal posttreatment ultrastructural changes observed were the reduction of mitochondrial swelling in granular cells and the reduction in the number of lipidlike vacuoles in corneocytes.