PS-14-001 Liver biopsy evaluation of autoimmune liver disease: autoimmune hepatitis and overlap syndrome

Background & Objective: Autoimmune hepatitis (AIH) is an inflammatory liver disease caused by T cell-mediated immune response targeting hepatocytes. The triggers of AIH are still unknown, but specific genetic and environmental factors are strongly related. AIH may be associated with an autoimmune cholangitis, giving rise to the overlap syndrome (OS). Currently there are not specific diagnostic criteria for OS, which should be classified according to the primary clinical and histological aspects. Liver biopsy is necessary to define the diagnosis of AIH/OS, to evaluate the grading, i.e. the necroinflammatory activity, the staging, i.e. the extent of liver fibrosis, and the response to therapy. Method: We assessed grading of the hepatitis, liver cell necrosis, plasma cell clusters, cholangitis activity (CA) and pattern of fibrosis in 35 cases of autoimmune liver disease. Results: 9 cases of AIH and 26 cases of OS were diagnosed. We revealed intense hepatitis activity in 6/9 of AIH and 15/26 of OS cases, CA2-CA3 in 22/26 cases of OS, necrosis in 21/35 cases, 9 with spotty and interface necrosis and 12 with bridging necrosis. Plasma cell clusters were present in all cases analysed. Fibrosis was present in 21/35 cases, bridging fibrosis in 16/35 cases. Conclusion: In our cases OS is not a rare disease. Since OS is not a specific entity but a spectrum from AIH to AIC, specifying the main disease is an important task of the pathologist in order to avoid undiagnosed OS, that may lead to steroid non-responding patients. Plasma cell clusters represent a relevant tool for the diagnosis of AIH/OS.