Secondary cutaneous oxalosis: cutaneous deposition of calcium oxalate dihydrate after long-term hemodialysis.

A 48-year-old Japanese man had miliary calcified papules on the distal fingers after long-term hemodialysis. The crystals in the dermis consisted of calcium oxalate, as revealed by light microscopy and scanning electron microscopy with energy-dispersive x-ray microanalysis. The calcium oxalate was in the form of a dihydrate crystal. Therefore a diagnosis of secondary cutaneous oxalosis was made. In cutaneous oxalosis that occurs as a result of hemodialysis, miliary deposits occur in the fingers, but not the toes, and are present more frequently on the palmar aspects of the fingers. This localization may result from local differences in the metabolism or concentration of calcium or oxalate, or changes in the blood circulation.