Melanosis coli

Overview


Melanosis coli is a disorder of pigmentation of the wall of the colon, identified at the time of colonoscopy. It is benign, and has no significant correlation with disease. The name is considered a misnomer: the brown pigment seen in the colon is actually lipofuscin, not melanin as the name implies.

The most common cause of melanosis coli is the surreptitious use of laxatives, and commonly anthraquinone containing laxatives such as Senna and other plant glycosides. Endoscopically, the mucosa shows a brownish discoloration in a moire pattern. On biopsy, melanosis coli shows characteristic pigment-laden macrophages within the submucosa on PAS staining.

No adverse effects or consequences of melanosis coli have been identified. The condition is unrelated to Peutz-Jeghers syndrome, which can cause pigmentation of the skin and mucous surfaces with melanin, and polyps in the digestive tract.

Melanoses of other parts of the gastrointestinal tract have also been reported, and are of unclear relevance. Patients with colostomies can have melanosis involving the stoma, which is also of no significance.