Melanosis coli, also pseudomelanosis coli, is a disorder of pigmentation of the wall of the colon, often identified at the time of colonoscopy. It is benign, and may have no significant correlation with disease. The brown pigment is lipofuscin in macrophages, not melanin.
The most common cause of melanosis coli is the extended use of laxatives, and commonly anthraquinone containing laxatives such as Senna and other plant glycosides. The anthranoid laxatives pass through the gastrointestinal tract unabsorbed until they reach the large intestine, where they are changed into their active forms. The resulting active compounds cause damage to the cells in the lining of the intestine and leads to apoptosis (a form of cell death). The damaged (apoptotic) cells appear as darkly pigmented bodies that may be taken up by scavenger cells known as macrophages. When enough cells have been damaged, the characteristic pigmentation of the bowel wall develops. The condition can develop after just a few months of laxative use.
No adverse effects or consequences of melanosis coli have been identified.
Relation to true melanoses
- Müller-Lissner, SA. (Oct 1993). "Adverse effects of laxatives: fact and fiction.". Pharmacology 47 (Suppl 1): 138–45. doi:10.1159/000139853. PMID 8234421.
- Byers, R.J.; Marsh, P.; Parkinson, D.; Haboubi, N.Y (October 2003). "Melanosis coli is associated with an increase in colonic epithelial apoptosis and not with laxative use". Histopathology 30 (2): 160–164. doi:10.1046/j.1365-2559.1997.d01-574.x. PMID 9067741.
- Wittoesch, JH.; Jackman, RJ.; McDonald, JR. "Melanosis coli: general review and a study of 887 cases.". Dis Colon Rectum 1 (3): 172–80. PMID 13537819.
- Vellappally, S.; Fiala, Z.; Smejkalová, J.; Jacob, V.; Somanathan, R. (2007). "Smoking related systemic and oral diseases.". Acta Medica (Hradec Kralove) 50 (3): 161–6. PMID 18254267.
- Ghadially, FN.; Walley, VM. (Sep 1994). "Melanoses of the gastrointestinal tract.". Histopathology 25 (3): 197–207. doi:10.1111/j.1365-2559.1994.tb01319.x. PMID 7821887.
- Fleischer, I.; Bryant, D. (May 1995). "Melanosis coli or mucosa ischemia? A case report.". Ostomy Wound Manage 41 (4): 44, 46–7. PMID 7598783.
- Endoscopic video of Melanosis coli, via the DAVE Project