Melanosis coli

Melanosis coli is a harmless condition that affects the large intestine (colon). In this condition, the lining of the colon turns dark brown or black due to a buildup of a pigment called lipofuscin. This pigment develops within cells that line the inside surface of the colon. Melanosis coli is noncancerous and typically related to the prolonged use of laxatives.

What are the symptoms of melanosis coli?

Melanosis coli usually doesn’t cause symptoms. Most people find out they have this condition when undergoing a colonoscopy for other reasons. If symptoms occur, they’re usually related to the underlying cause, such as constipation or regular laxative use.

What causes melanosis coli?

The main cause of melanosis coli is long-term use of certain laxatives, especially those containing substances called anthraquinones. These laxatives stimulate the bowel and include products containing senna, cascara, and aloe. When used frequently, these substances lead to pigment buildup within colon cells.

How is this diagnosis made?

Melanosis coli is typically diagnosed during a colonoscopy, a procedure where a doctor examines the inside of the colon using a thin, flexible tube with a camera. During this examination, the colon’s lining appears dark brown or black instead of its usual pink color. If needed, the doctor may take a small biopsy (tissue sample) to examine under the microscope.

What does melanosis coli look like under the microscope?

Under the microscope, melanosis coli shows cells filled with a brownish-black pigment known as lipofuscin. This pigment gives the tissue a dark, speckled appearance. The pigment is mainly seen within cells called histiocytes, which are normally present in the colon lining and help clear away cellular debris.

Is melanosis coli something to be concerned about?

Melanosis coli itself is not harmful and does not increase your risk of colon cancer. However, it indicates chronic laxative use, which can lead to other health problems. If melanosis coli is diagnosed, your doctor may recommend reducing or stopping the use of stimulant laxatives. It’s also important because it may mask or obscure other conditions during colonoscopy, making examinations slightly more challenging. Always discuss any concerns or treatment changes with your doctor.