Frontiers CD8+ T Cell Exhaustion Phenotype in Chronic Hepatitis C Virus Infection Is Associated With Epitope Sequence Variation 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 Frequency Distribution of Hepatitis C Virus Genotypes with Reference to Age and Sex in Various Districts of Khyber Pakhtunkhwa, Pakistan European Medical Journal 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 An unusually pigmented colon The Lancet Gastroenterology & Hepatology