One of several disorders of melanin pigmentation resulting in increased melanin in either the epidermis (melanoderma), in which case the coloration is brown, or in the dermis, in which ease it is blue or slate gray (ceruloderma). This disorder may be caused by a number of diseases and conditions, including pregnancy, ACTH-producing tumors, Wilson’s disease, porphyria, biliary cirrhosis, chronic renal failure, certain drugs, suntanning, and chronic pruritus.