Colonoscopic Lesion Detection in Melanosis Coli-Stars in the Night Sky or a Dark Cave with Dim Torchlight?

Abstract

Purpose: Melanosis Coli is brownish discoloration of colonic mucosa due to the uptake of lipofuscin in macrophages from anthraquinone laxative use. Previous studies have suggested that the polyp and adenoma detection in the setting of melanosis coli should be easier given these differences. The study compared polyp and adenoma detection rates among individuals with melanosis coli compared with age/gender matched general population. Methods: Single center, retrospective cohort study during which results 6,471 colonoscopies performed by one attending gastroenterologist and 21 gastroenterology fellows. Polyp and adenoma detection rates were calculated for the general and melanosis coli populations via keyword searches in the colonoscopy report database. STATISTICAL ANALYSIS: Polyp and adenoma detection rates in the general and melanosis coli populations were compared using chi-squared test with two-sided p-value; p<0.05 indicating significance. Results: In the general population undergoing colonoscopy, polyps were detected in 2595 of 6471 colonoscopies revealing a polyp detection rate of 39.96%. Pathology was available from 5429 colonoscopies and adenomatous polyps were detected in 1004, indicating an adenoma detection rate of 18.49%. Melanosis coli was found in 56 colonoscopies with polyps detected in nine and adenomas detected in four, demonstrating polyp and adenoma detection rates of 16.07% and 7.14% respectively. The polyps detected in melanosis coli patients were detected in all colon segments. Both polyp and adenoma detection rates were found to be significantly less in the setting of melanosis coli (p-values = 0.0003, 0.0291) than in the general population. Conclusion: Colonic polyps and adenomas were detected at a significantly lower rate in the setting of melanosis coli. Detection rates in melanosis coli may have been reduced due to the dark pigmentation of the colonic mucosa making visualization of lesions throughout the colon more difficult. Our results are contradictory to previously less rigorous studies on the subject. Given the lesser polyp and adenoma detection rates demonstrated in the melanosis coli population, our study emphases that careful attention and diligence is required for colonoscopic lesion detection in this population.Figure: [547]