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.