LOCALIZED CHRYSIASIS INDUCED BY LASER THERAPY

Background: Chrysiasis is a rare blue-gray skin discoloration that occ urs in sun-exposed sites of some patients who receive gold salts. A un ique case of localized chrysiasis developed immediately after Q-switch ed ruby laser (694 nm) irradiation for postinflammatory hyperpigmentat ion secondary to granuloma faciale in a patient who was receiving long -term gold sodium thiomalate therapy for psoriatic arthritis. Skin bio psy specimens showed striking changes in the ultrastructural character istics of cutaneous gold deposits following laser treatment. Observati ons: A blue-gray skin discoloration developed immediately after laser exposure and persisted unchanged after 1 year. Transmission electron m icroscopy of skin biopsy specimens showed electron-dense gold de posit s. Before laser irradiation, these deposits were 106+/-35 (mean+/-SD) nm in diameter and faceted, consistent with a crystalline structure. P osttreatment deposits were round, smaller, measured 16+/-4 nm, and res embled colloidal gold. Identical findings were observed in an area of sun-protected skin treated with the Q-switched ruby laser; irradiation with a pulsed dye laser at 585 nm had no effect. Conclusions: Localiz ed chrysiasis was induced in a patient receiving parenteral gold thera py who underwent treatment with a Q-switched ruby laser. This form of chrysiasis resulted from a structural alteration in dermal gold deposi ts. A similar physicochemical modification in gold deposits induced by UV light may explain the localization of chrysiasis to sun-exposed sk in in affected patients.