Colon
Other nonneoplastic
Melanosis coli


Topic Completed: 1 October 2013

Minor changes: 1 October 2020

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PubMed Search: melanosis coli

Raul S. Gonzalez, M.D.
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Cite this page: Gonzalez R. Melanosis coli. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colonmelanosis.html. Accessed January 22nd, 2021.
Definition / general
  • Deposition of dark melanin-like pigment in colonic macrophages after ingestion of laxatives
  • Common endoscopic finding
Sites
  • Can involve all parts of colon and rectum, but typically spares mucosal regions with lymphoid nodules, polyps or carcinomas
  • Should biopsy nonpigmented regions in these patients
Etiology
  • Linked to use of anthraquinone laxatives, but may be secondary to any increase in colonic epithelium apoptosis (Histopathology 1997;30:160)
Clinical features
Diagnosis
  • Colonoscopy
Case reports
Gross description
  • Diffuse brown-black discoloration of colonic mucosa
Microscopic (histologic) description
  • Diffuse deposition of "melanized ceroid" in macrophages of lamina propria (Gastrointest Endosc 1997;46:131)
  • Silver stains may show abnormalities of myenteric plexus
Microscopic (histologic) images

Contributed by Yuri Tachibana, M.D.

Pigment in lamina propria



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Colonic mucosa

Positive stains
Negative stains
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Melanosis coli

Differential diagnosis
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