Adult, acquired reactive perforating collagenosis. Report of a case including ultrastructural findings.

A case of reactive perforating collagenosis in an adult male patient with chronic renal failure. Pruritic, umbilicate papules, showing extrusion of collagen fibers through the epidermis were detected histopathologically. Electron microscopy showed absence of basal membrane beneath the perforation and collagen fibers with preserved periodicity passing through widened intercellular spaces with islands of cytoplasmic material.