Silver-blue nails.

The case is reported of a man with uniformly silver-blue discolouration of all fingernails, with deeper colouring over the lunulae. The nail bed changes resulted from the uncontrolled ingestion of a silver-containing granular powder. The total silver intake was over 15 g. The only other sign of argyrosis was a barely perceptible greyish discolouration over the cheeks and in the sclerae. Biopsies were taken from the nail bed and the cheek. Electron microscopy revealed metallic deposits in elastic fibres and basement membranes. The silver deposition was much heavier in the nail bed than in facial skin. Long-wave ultraviolet light (UVA) and lack of melanin protection seem to be responsible for this phenomenon. Argyrosis and the differential diagnosis of nail discolourations are reviewed.