Morphological lesions detected by light and electron microscopies in chronic type C hepatitis

HCV infection results in chronic hepatitis in most patients. The mechanisms determining liver damage and the events that lead to a high rate of chronic hepatitis remain unclear. In present study, an attempt was made to sum up data on lesions in the liver in the course of chronic type C hepatitis including those of our own cases, because that pattern is still a matter of debate. Cell lesions detected by light microscopy are characteristic but not specific and included inflammatory lesions of low or moderate intensity and a mild extent of fibrosis in the liver. The common and most characteristic trait of chronic HCV infection involves lesions in hepatocyte nuclei. These changes involved swelling, altered shape, hyperchromasia, disturbed nuclear chromatin structure, enlarged and frequently multiple nucleoli and lesions of nuclear envelope. Complexes of tubules or branching fibrils of 20-30 nm in diameter were present in cell nuclei at electron microscope level. The nuclear lesions were accompanied in the same cells by changes in rough endoplasmic reticulum with long tubular structures or branching fibrills inside. Other cytoplasmic changes included mitochondrial lesions, numerous lipid vacuoles and free tubular structure of a highly osmophilic character. Cellular localisation of HCV proteins using immunocytochemical techniques remains to be a matter of studies. In most studies HCV proteins have been detected in the cytoplasm although some reports indicate nuclear localisation, especially of C protein. All our observations on morphological lesions in chronic type C hepatitis can generally confirm most of data of other authors, but the criteria of nuclear lesions defined at the ultrastructural level represent the original input of our studies. The studies using molecular biology techniques should be continued at the electron microscope level.