Melanosis coli** Melanosis coli is a benign, reversible condition characterized by brown black pigmentation of the colonic mucosa, most often due to chronic use of anthraquinone laxatives. The discoloration is caused “Melanosis” in the small and large intestine Melanosis Coli El Atlas Gastrointestinal gastrointestinalatlas.com “Melanosis” in the small and large intestine Melanosis Coli El Atlas Gastrointestinal gastrointestinalatlas.com