Melanosis coli

Melanosis coli denotes brownish discoloration of the colonic mucosa found on endoscopy or histopathologic examination. The condition has no specific symptom on its own. It is a fairly frequent incidental finding of colonic biopsies and resection specimens. The pigmentation is caused by apoptotic cells which are ingested by macrophages and subsequently transported into the lamina propria, where lysosomes use them to produce lipofuscin pigment, not melanin as the name suggests. Melanosis coli develops in over 70% of persons who use anthraquinone laxatives (eg cascara sagrada, aloe, senna, rhubarb, and frangula), often within 4 months of use. Long-term use is generally believed to be necessary to cause melanosis coli. The condition is widely regarded as benign and reversible, and disappearance of the pigment generally occurs within a year of stopping laxatives. Although often due to prolonged use of anthraquinone, melanosis can probably result from other factors or exposure to other laxatives. It has been reported as a consequence of longstanding inflammatory bowel disease. Some investigators suggested that increase in apoptosis of colonic mucosa by anthraquinone laxatives increased the risk of colonic cancer. Recent data, including those from large-scale retrospective, prospective and experimental studies, did not show any increased cancer risk. IeJSME 2012: 6 (Suppl 1): S53-60