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: a contrast effect or an oncogenic effect? A large scale retrospective cohort study International Journal of Colorectal Disease Springer Nature Link Melanosis coli: A comprehensive review Gastroenterologa y Hepatologa (English Edition) This is a very rare case of metastatic oral mucosal melanoma to the colon with an unusual presentation mimicking melanosis coli. The colonoscopy findings show no mass effect but multiple hyperpigmented lesions Colorectal Anatomy and ICD O 3 SEER Training