Melanosis coli

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Melanosis coli identified on colonoscopy as a brownish moire pattern on the wall of the colon.
Melanosis coli identified on colonoscopy as a brownish moire pattern on the wall of the colon.
H & E stain of colon biopsy showing melanosis coli, which appears as brown pigmentation in the macrophages in the lamina propria.
H & E stain of colon biopsy showing melanosis coli, which appears as brown pigmentation in the macrophages in the lamina propria.

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. [1] 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.[2]

No adverse effects or consequences of melanosis coli have been identified.[2] 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.[3] Patients with colostomies can have melanosis involving the stoma, which is also of no significance.[4]

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[edit] References

  1. ^ Muller-Lissner SA. Adverse effects of laxatives: fact and fiction. Pharmacology. 1993 Oct;47 Suppl 1:138-45. PMID 8234421
  2. ^ a b Wittoesch JH, Jackman RJ, McDonald JR. Melanosis coli: general review and a study of 887 cases. Dis Colon Rectum. 1958 May-Jun;1(3):172-80. PMID 13537819.
  3. ^ Ghadially FN, Walley VM. Melanoses of the gastrointestinal tract. Histopathology. 1994 Sep;25(3):197-207. PMID 7821887
  4. ^ Fleischer I, Bryant D. Melanosis coli or mucosa ischemia? A case report. Ostomy Wound Manage. 1995 May;41(4):44, 46-7. PMID 7598783

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