Primary sclerosing cholangitis. Light and electron microscopy of hepatic tissue in two cases

In an 18 year-old woman presenting with an intra- and extrahepatic form of sclerosing cholangitis needle biopsy of the liver revealed, in addition to a conspicuous proliferation of biliary ductules and mild inflammatory infiltrations of the portal tract, piece-meal necroses and focal intralobular inflammatory changes. In the second case - a 49-year-old man - presenting with an extrahepatic location of stenoses there were infrequent proliferating biliary ductules in the enlarged fibrotic portal tracts. Ultrastructural investigations revealed in both patients adverse regressive changes in the epithelium of proliferating biliary ductules, seen as microvillous damage on the luminal surface, dilation of the endoplasmic reticulum and mitochondrial swelling; in the second patient there was, moreover, electrondense material in epithelial cytoplasm, probably corresponding to bile components. In the first patient predominated among ultrastructural changes increase of cytoskeletal filaments in some epithelia and pronounced reduplication of the basement membranes of small biliary ducts. These "cholestatic" modifications, expressed in different form in the two patients, were accompanied by dilatation and damage, sometimes total disappearance of microvilli of biliary canaliculi.