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

Abstract

Apart from serological diagnosis of chronic type B hepatitis, of high importance is specific morphological diagnosis, based on evaluation of liver biopsies. In the evaluation, the techniques are employed, which directly visualize the virus in the cells (electron microscopy) as well as the techniques of cell biology which demonstrate the presence of viral genetic material and viral proteins in situ. This paper reviews the available data on the diagnosis of liver pathomorphology using the above mentioned techniques in chronic HBV infections in adults. The data have been compared with the results of our own studies, performed in children. In chronic type B hepatitis and more frequently in children than in adults, slight or moderate inflammation (grade 1 to 2) and insignificantly advanced fibrosis (stage 1 to 2) are noted in the liver. Both in children and in adults, lesions in hepatocyte nuclei represent the common morphological denominator in the patterns of light and electron microscopy. The cell nuclei are of variable size, irregular shape, they stain irregularly, manifest an altered outline of nuclear envelope, frequently exhibit numerous and enlarged cell nucleoli and chromatin dissociation (the so called empty cell nuclei). In ultrastructural studies, hepatocyte cytoplasm contains Dane's bodies and tubular forms of HBsAg while virus-resembling particles are noted in cell nuclei. Molecular biology techniques (immunocytochemistry, in situ hybridisation) reveals nuclear and/or cytoplasmic location of HBcAg, cytoplasmic location of HBsAg and a similar location of HBV DNA. The data permit us to determine precisely the stage of infection and to make appropriate therapeutic decisions.