Pseudomelanosis coli, its relation to laxative use and association with colorectal neoplasms: A comprehensive review

Pseudomelanosis coli is historically associated with anthraquinone laxatives and is often used as a surrogate marker for chronic laxative use. The opioid epidemic has seen an increase in laxative use for chronic constipation. Anthraquinone laxatives have demonstrated tumorigenic potential in animal studies due to their apoptotic effects on colonic epithelial cells. Colorectal cancer is associated with significant mortality and morbidity worldwide. Human studies have not shown a significant correlation between anthraquinone laxative use, pseudomelanosis coli, and colorectal carcinoma. The characteristic pigmentation of pseudomelanosis also appears to be absent macroscopically and on histology of neoplastic epithelium. However, there appears to be a slightly higher risk of adenoma development. This has been attributed to a higher polyp detection rate during endoscopy on account of the color contrast between the polyp against a darker background of pseudomelanosis.