Colon non tumor
Nonneoplastic, noncongenital lesions
Melanosis coli

Author: Raul S. Gonzalez, M.D.

Revised: 15 May2018, last major update October 2013

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: melanosis coli
Cite this page: Gonzalez, R.S. Melanosis coli. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colonmelanosis.html. Accessed July 21st, 2018.
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
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 PathOut server:

Contributed by Yuri Tachibana, M.D., Nagasaki University

Pigment in lamina propria



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
Videos

Melanosis coli

Differential diagnosis