[The role of liver biopsy in the diagnosis of autoimmune hepatitis]

Abstract

Autoimmune hepatitis is a progressive inflammatory hepatitis of unknown etiology. The diagnosis of autoimmune hepatitis is guided by the descriptive criteria and score system implemented by the International Autoimmune Hepatitis Group in 1994. In addition to clinical and laboratory data and the presence of autoantibodies, liver biopsy plays an important role in the diagnostic regimen. Previous studies have emphasized that the histological picture of autoimmune hepatitis was characteristic but not pathognomic for the disease, therefore diagnosis was based on the exclusion of other chronic liver diseases. The goal of this study is to summarize the experiences based on the examination of 93 liver biopsies from 87 patients suffering from autoimmune hepatitis in the Department of Pathology St. László Hospital, Budapest, during the period of 2000-2006. The morphological picture was evaluated based on the criteria of Histological Activity Index as well as other histological features. In addition it was compared to the usual histological characteristics of viral hepatitis, most importantly hepatitis C. The morphological changes examined first were the ones that constitute the diagnostic criteria of autoimmune hepatitis: the severity of portal inflammation and interface hepatitis, the cell composition of the inflammation, rosette formation of periportal hepatocytes, and the presence and extent of centrilobular and bridging necrosis. Results indicated that in most cases the portal/periportal inflammation was very active and lead to the destruction of the original liver structure which was followed by regeneration process (periportal rosettes). Among the inflammatory cells, plasma cells were predominant. In the majority of the cases severe centrilobular and/or bridging necrosis was also present, which strongly elevated the index number, approaching the maximum value. In most patients, only mild fibrosis was observed and merely a handful had progressed to cirrhosis. In conclusion the morphological picture of autoimmune hepatitis is not only characteristic but also pathognomic for the disease. Of course, additional data on clinical and biochemical findings, circulating autoantibodies, and abnormal levels of serum globulins are also necessary for correct diagnosis of autoimmune hepatitis.