Oral pigmentations may be focal, diffuse, or multifocal. They may be blue, purple, brown, gray, or black. They may be flat or tumefactive. Importantly, some are harbingers of internal disease; some are localized harmless accumulations of melanin,
hemosiderin, or exogenous metal; and some can be highly lethal. The differential diagnosis can be lengthy, particularly when the pigmentation is macular and diffuse or multifocal. Although biopsy is a helpful aid to diagnosis for localized lesions, the more diffuse lesions will require a thorough history and laboratory studies in order to arrive at a definitive diagnosis.