Retrospective studies on clinical features of melanosis of the colon and its correlation with the polypus and carcinoma of large intestine

Objective To investigate the clinical characteristics of melanosis of the colon (MC) and its correlation with polypus and carcinoma of the large intestine. Methods Clinical feature and colonoscopic findings of 156 MC patients were retrospectively analyzed. Final diagnosis of MC case was made after colonoscopic and pathological examination, and data of the case history was recorded. Results The overall detection rate of MC was 1.12%, with 0.46% in males, 0.66% in females. An 82.69% of the patients suffered various constipations and had a history of taking cathartics. The clinical manifestation of total-colon melanosis occurred in 83.97% of the patients. There was no significant difference between the rate of concomitant polypus (27.56%) in the MC patients and the detection rate of polypus in the patients who underwent a synchronous colonoscopy ( χ 2 = 1.205, P = 0.298). Also there was no significant difference between the detection rate of carcinoma of the large intestine (8.97%) in MC patients and the detection rate of the same disease in the patients who underwent synchronous colonoscopy ( χ 2 = 0.268, P = 0.604). A logistic regression analysis has shown that the older the age of MC patients is, the more opportunities of MC and the concomitant polypus would occur. Conclusion MC may be related to constipations and a long-term administration of cathartics, among which total-colon melanosis ranks first in the cases. There is an earlier age of onset in the females, with a higher detection rate. The older the age of the patients is, the higher the detection rate of MC is, and the more possibility the onset of the concomitant polypus.