Primary sclerosing cholangitis, stage 2

A bile duct (arrow) with periductal fibrosis. The lining epithelium shows mucinous metaplasia as shown by the finely vacuolated cytoplasm of the epithelial cells lining the duct. The thick arrow indicates an atrophic bile duct that is almost totally replaced by fibrous tissue, on its way to becoming a bile duct scar.