Acquired perforating dermatosis of diabetes mellitus and renal failure: further ultrastructural clues to its pathogenesis.

An ultrastructural study of a typical case of acquired perforating dermatosis in a patient with renal failure and diabetes mellitus is reported. Crystal-like microdeposits of an electron-lucid material were detected in the upper dermis, close to the transepidermal channel. Compact macrophage conglomerations surrounded the deposits, and a strong histiocytic response was present. Mononuclear inflammatory cells of "activated" type penetrated the acanthotic epidermis provoking basement membrane dissolution and widening of interkeratinocyte spaces. Collagen fibers were seen in the keratotic plug, indicating the process of transepidermal elimination. Our observation supports the hypothesis suggesting that some kind of storage phenomenon may be at the origin of perforating skin lesions in renal failure patients.