Melanosis coli

Melanosis coli denotes brownishdiscoloration of the colonic mucosa found on endoscopyor histopathologic examination. The condition hasno specific symptom on its own. It is a fairly frequentincidental finding of colonic biopsies and resectionspecimens. The pigmentation is caused by apoptotic cellswhich are ingested by macrophages and subsequentlytransported into the lamina propria, where lysosomesuse them to produce lipofuscin pigment, not melaninas the name suggests. Melanosis coli develops in over70% of persons who use anthraquinone laxatives (egcascara sagrada, aloe, senna, rhubarb, and frangula),often within 4 months of use. Long-term use is generallybelieved to be necessary to cause melanosis coli.The condition is widely regarded as benign andreversible, and disappearance of the pigment generallyoccurs within a year of stopping laxatives. Althoughoften due to prolonged use of anthraquinone, melanosiscan probably result from other factors or exposure toother laxatives. It has been reported as a consequenceof longstanding inflammatory bowel disease. Someinvestigators suggested that increase in apoptosis ofcolonic mucosa by anthraquinone laxatives increased therisk of colonic cancer. Recent data, including those fromlarge-scale retrospective, prospective and experimentalstudies, did not show any increased cancer risk.