Diffuse cutaneous melanosis is a rare complication of metastatic melanoma related
to a worse prognosis. There are few cases reported in the literature. Its
pathogenesis has not been completely elucidated, although studies have suggested
certain mechanisms for its occurrence. It is clinically manifested as a
blue-gray discoloration of the skin and mucous membranes in a cephalo caudal
progression and usually associated with melanuria. Skin and mucosa
histopathology reveals only the presence of melanophages in the dermis, mainly
perivascular, and free interstitial melanin. We report the case of a 68-year-old
male with metastatic melanoma, diffuse hyperpigmentation of the skin and
melanuria.