Pseudo-obstruction with pitch black colon--a very rare presentation of melanosis coli.

Melanosis coli is associated with an increased risk of colorectal tumors but is not agreed to be a precancerous lesion. The condition has been associated with the ingestion of anthracene laxatives and is believed to be caused by increased epithelial apoptosis. Although melanosis coli is a frequent finding in colonic biopsies and resection specimens, to our knowledge severe jet black melanosis coli with pseudoobstruction has not been reported in literature. Such gross Melanosis is exceptional and particularly striking.