Frontiers CD8+ T Cell Exhaustion Phenotype in Chronic Hepatitis C Virus Infection Is Associated With Epitope Sequence Variation Interpretation of Hepatitis C Test Results: Guidance for Laboratories Hepatitis C virus An Overview 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 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