Colon non tumor
Non-neoplastic, non-congenital lesions
Melanosis coli

Author: Raul S. Gonzalez, M.D. (see Authors page)

Revised: 9 January 2017, last major update October 2013

Copyright: (c) 2003-2017,, Inc.

PubMed Search: melanosis coli
Cite this page: Melanosis coli. website. Accessed March 20th, 2018.
Definition / general
  • Deposition of dark melanin-like pigment in colonic macrophages after ingestion of laxatives
  • Common endoscopic finding
  • 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
  • Linked to use of anthraquinone laxatives, but may be secondary to any increase in colonic epithelium apoptosis (Histopathology 1997;30:160)
Clinical features
  • Colonoscopy
Case reports
Clinical images

Images hosted on other servers:

Darkly pigmented colonic mucosa

Colonoscopic appearance

Colon appeared dark brown and black

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

Images hosted on other servers:

Accumulation of brown melanosis pigment

Pigment laden macrophages in colonic mucosa

Macrophages engorged with brown pigment

Colonic mucosa

Positive stains
Negative stains

Melanosis coli
Differential diagnosis