Medical Author: Melissa C. Stöppler, MD
Medical Editor: Jay W. Marks, MD

• What is melanosis coli?
• What are the symptoms of melanosis coli?
• What causes melanosis coli?
• How is melanosis coli diagnosed?
• What is the prognosis (outcome) of melanosis coli?

What is melanosis coli?

Melanosis coli is a condition usually associated with chronic laxative use in which dark pigment is deposited in the lamina propria (one of the lining layers) of the large intestine (colon). The pigment deposition results in a characteristic dark brown to black discoloration of the lining of the large intestine. This condition is sometimes called pseudomelanosis coli because the pigment deposits consist of a pigment known as lipofuscin and do not contain melanin as implied by the term “melanosis.” Lipofuscin is a cellular pigment that forms when cells are destroyed, often called “wear and tear” pigment that can be found throughout the body.

The dark color of the intestinal lining may be uniform or patterned, and the discoloration may be slight or very pronounced. The intensity and pattern of the discoloration may even vary among different sites in the colon of a patient. The condition may also be reversed upon discontinuation of laxative use. In some cases, the wall of the colon appears normal to the eye, but microscopic evaluation of biopsies by a pathologist reveals areas of pigment in the colon's lining. The pigment in melanosis coli does not accumulate in polyps or tumors of the large intestine.

What are the symptoms of melanosis coli?

Melanosis coli does not cause symptoms.

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