Sclerosing cholangitis associated with ulcerative colitis. Light and electron microscopy studies.

The light and electron microscopy findings of liver biopsies from four patients with sclerosing cholangitis and ulcerative colitis are described. The main histologic feature was mesenchymal proliferation involving phagocytic, fibroblastic and immunocytic cells suggestive of an immunologic type of liver injury which may attack bile duct epithelial cells. Other histologic features, included the presence of myelin fibers in both hepatocytes and bile duct epithelial cells and an abundant amount of lysosome-like structures. The significance of these findings is discussed.