Melanosis Coli: A Helpful Contrast Effect or a Harmful Pigmentation?

Area of Science:

• Gastroenterology
• Endoscopy
• Oncology

Background:

• Melanosis coli, a benign colonic mucosal discoloration, is associated with chronic anthranoid laxative use.
• Emerging data suggest a link between melanosis coli and increased adenoma detection rates.
• The tumorigenic potential and association with colorectal cancer (CRC) development remain uncertain.

Purpose of the Study:

• To compare polyp detection rates in patients with and without melanosis coli.
• To evaluate the association between melanosis coli and colorectal cancer diagnosis.
• To investigate the impact of melanosis coli on endoscopic findings.

Main Methods:

• Retrospective, single-center study including patients diagnosed with melanosis coli via colonoscopy over 15 years.
• Each melanosis coli case was matched with three controls based on age, gender, setting, and indication.
• Polyp detection rates and CRC diagnoses were compared between groups, with and without adjustment for bowel preparation.

Main Results:

• A cohort of 718 melanosis coli patients and 2154 controls was analyzed.
• Polyp detection rates were significantly higher in the melanosis coli group (33.4%) compared to controls (21.8%).
• Melanosis coli was associated with a lower diagnosis rate of colorectal cancer (0.3% vs 3.9%) and significantly higher polyp detection (OR=1.986).

Conclusions:

• Melanosis coli is not associated with an increased risk of colorectal cancer diagnosis.
• The condition is linked to enhanced polyp detection, potentially due to a chromo-endoscopy-like effect.
• This suggests melanosis coli may improve adenoma visualization during colonoscopy.