Melanosis Coli

This light brown pigmentation is caused of longstanding use of anthraquinone laxatives, and it disappears, when the use is stopped. The melanosis (sometimes this condition is called pseudomelanosis coli) does not probably cause any symtoms, but is a strong indication of laxative abuse.

Most often all parts of the colon is affected, sometimes however only the caecum and/or the rectum. The first two pictures are from the caecal region, and the third picture from the transversum, where the mucosa is quite unaffected.

This is a typical colonoscopic finding. Histologically macrophages containing dark granular pigment is seen within the lamina propria. Histologic changes can be seen at an earlier stage, before macroscopic changes have appeared.

Small spots of the mucosa can be spared and left without any pigmentation, and the finding can then be misleading, perhaps reminding of some aphthous lesions in the colon mucosa.