Benign Discoloration Poses Questions Melanosis Coli: A Case of Mistaken IdentityA Case Report The Permanente Journal Melanosis coli is dark brown black pigmentation of colorectal mucosa associated with chronic use of laxatives containing anthraquinone. Examples of such laxatives include senna and rhubarb derivatives. Clinical Importance: There is no association MELANOSIS COLI** Melanosis coli is a disorder of pigmentation of the bowel wall. Histology demonstrates pigment laden macrophages It is associated with laxative abuse, especially **anthraquinone compounds such as senna** An unusually pigmented colon The Lancet Gastroenterology & Hepatology