Melanosis coli: a contrast effect or an oncogenic effect? A large-scale retrospective cohort study

• Published in: International journal of colorectal disease Vol. 38; no. 1; p. 63
• Main Authors: Wang, Yan, Li, Longsong, Niu, Xiaotong, Gao, Fei, Chai, Ningli, Linghu, Enqiang
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 08.03.2023
• Subjects: Adenoma - diagnosis; Adenoma - pathology; Colonic Diseases; Colonic Polyps - diagnosis; Colonic Polyps - pathology; Colonoscopy; Colorectal Neoplasms - pathology; Gastroenterology; Hepatology; Humans; Internal Medicine; Medicine; Medicine & Public Health; Melanosis - diagnosis; Proctology; Retrospective Studies; Surgery; Serrated polyps; Adenoma detection rate; Carcinoma; Melanosis coli; Advanced adenoma
• ISSN: 1432-1262; 1432-1262
• DOI: 10.1007/s00384-023-04357-1

Background Melanosis coli is characterized by brown mucosa with pigmentation. Studies have showed an increased adenoma detection rate in melanosis patients, whether it is caused by a contrast effect or an oncogenic effect is still controversial. The detection of serrated polys in melanosis patients remains unknown. Aims The study aimed to clarify the correlation of adenoma detection rate with melanosis coli and discuss outcomes in less-experienced endoscopists. Serrated polyp detection rate was also been investigated. Methods A total of 2150 patients and 39,630 controls were enrolled. A propensity score matching method was used to balance covariates between the two groups. The detection of polyps, adenomas, serrated polyps, and their features was analyzed. Results The polyp detection rate (44.65% vs 41.01%, P  = 0.005) and adenoma detection rate (30.34% vs 23.92%, P  < 0.001) were significantly higher, and the serrated polyp detection rate (0.93% vs 1.58%, P  = 0.033) was significantly lower in melanosis coli. The percentage of low-risk adenomas (44.60% vs 39.16%, P  < 0.001) and polyps with 6 to 10 mm in size (20.16% vs 16.21%, P  < 0.001) were higher in melanosis coli. The detection of large serrated polyps was lower (0.11% vs 0.41%, P  = 0.026) in melanosis coli. Conclusion Melanosis coli correlates with an increased adenoma detection rate. The detection of large serrated polyps was lower in melanosis patients. Melanosis coli may not be considered a precancerous lesion.