Melanosis coli: a disappearing act Gastrointestinal Endoscopy 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 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 Interpretation of Hepatitis C Test Results: Guidance for Laboratories Hepacivirus C Encyclopedia MDPI