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The

n e w e ng l a n d j o u r na l

of

m e dic i n e

images in clinical medicine

Melanosis Coli A

B

C

A 

50-year-old woman underwent colonoscopy for rectal bleeding. S.T. Kew, F.R.C.P. Her entire colon appeared dark brown and black, a finding consistent with Srikumar Chakravarthi, M.D. the diagnosis of melanosis coli (Panel A). Random biopsy specimens from International Medical University the descending colon revealed sheets and clusters of macrophages laden with Kuala Lumpur, Malaysia brownish pigment in the lamina propria (Panel B, arrow). A tiny, unpigmented kew@imu.edu.my polyp (approximately 2 to 3 mm in diameter) was seen in the rectum (Panel C); histopathological examination revealed a tubular adenoma. Mild internal hemorrhoids were the cause of the rectal bleeding. The patient reported taking rhubarb and cascara-containing complementary medicine as mild laxatives for years. The active ingredient in these substances is anthraquinone, which causes injury to the colonic epithelial cells, resulting in the production of lipofuscin, the dark pigment seen in melanosis coli. The condition is benign and reversible. Disappearance of the pigment generally occurs within a year after a patient stops taking anthraquinone. The detection of adenomas may be easy in a patient with melanosis coli because of the pigmented backdrop. DOI: 10.1056/NEJMicm1204882 Copyright © 2013 Massachusetts Medical Society.

n engl j med 368;24  nejm.org  june 13, 2013

The New England Journal of Medicine Downloaded from nejm.org on July 6, 2013. For personal use only. No other uses without permission. Copyright © 2013 Massachusetts Medical Society. All rights reserved.

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