Melanosis coli

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.

Melanosis coli
Melanosis coli identified on colonoscopy as a brownish moiré pattern on the wall of the colon.
Micrograph of melanosis coli, with the characteristic mucosal lipofuscin-laden macrophages (brown).

Cause
Further information: Factitious diarrhea

The most common cause of melanosis coli is the extended use of laxatives, and commonly anthraquinone containing laxatives such as senna, aloe vera and other plant glycosides.[1] 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.[2]

However, other causes are identified, including an increase in colonic epithelial apoptosis.[3] Endoscopically, the mucosa may show a brownish discoloration in a moiré pattern.

Histologic appearance

On biopsy, melanosis coli shows characteristic pigment-laden macrophages within the mucosa on PAS staining.[4]

The histologic differential diagnosis of mucosal pigmentation is: lipofuscin (melanosis coli), hemosiderin-laden macrophages, and melanin (rare).

Prognosis

No adverse effects or consequences of melanosis coli have been identified.[4]

Relation to true melanoses

The condition is unrelated to true melanoses, such as Peutz–Jeghers syndrome and smoker's melanosis.[5]

Peutz–Jeghers syndrome causes pigmentation of the skin and mucous surfaces with melanin, and polyps in the digestive tract.

Non-colonic pseudomelanoses

Pseudomelanoses of other parts of the gastrointestinal tract have also been reported, and are of unclear relevance.[6]

Patients with colostomies can have melanosis involving the stoma, which is also of no significance.[7]

gollark: The median is different.
gollark: * the mean
gollark: Nope, that's the formula for a mean.
gollark: That is the mean for discrete things. The median would be the middle one if you put them all in sorted order.
gollark: If you just have a giant list of measurements from a random thing, add them up and divide by the number of measurements you have.

References
  1. Müller-Lissner, SA. (Oct 1993). "Adverse effects of laxatives: fact and fiction". Pharmacology. 47 (Suppl 1): 138–45. doi:10.1159/000139853. PMID 8234421.
  2. http://www.medicinenet.com/melanosis_coli/page2.htm
  3. 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.
  4. Wittoesch, JH.; Jackman, RJ.; McDonald, JR. "Melanosis coli: general review and a study of 887 cases". Dis Colon Rectum. 1 (3): 172–80. doi:10.1007/bf02616828. PMID 13537819.
  5. 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. doi:10.14712/18059694.2017.76. PMID 18254267.
  6. 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.
  7. Fleischer, I.; Bryant, D. (May 1995). "Melanosis coli or mucosa ischemia? A case report". Ostomy Wound Manage. 41 (4): 44, 46–7. PMID 7598783.
Classification
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.