Argyria: the intradermal "photograph," a manifestation of passive photosensitivity.

X-ray microprobe and electron microscopic study was made of the remarkable blue-black pigmentation that sunlight elicits in patients with argyria. The patient under study had developed argyria following injection of silver nitrate as a sclerosant into his varicose veins 41 years ago. Similarities are demonstrated between the darkening of the skin and the darkening of a photographic film following light exposure. In both instances, colorless silver salts and compounds present in an inert matrix (collagen versus gelatin) are reduced by incident light to black metallic silver. This passive photosensitivity reaction leads to silver tattooing of the light-exposed skin and to photographic imaging in the film.