Hepacivirus C Encyclopedia MDPI Photomicrograph of an endoscopic colon biopsy (colonoscopy) showing melanosis coli, an accumulation of brown pigment (lipofuscin) within macrophages of the colonic mucosa, related to use of laxatives. Stock Photo Adobe Stock Melanosis coli: a disappearing act Gastrointestinal Endoscopy An unusually pigmented colon The Lancet Gastroenterology & Hepatology This is a very rare case of metastatic oral mucosal melanoma to the colon with an unusual presentation mimicking melanosis coli. The colonoscopy findings show no mass effect but multiple hyperpigmented lesions Melanosis coli Wikipedia