A practical histological approach to the diagnosis of autoimmune hepatitis: experience of an Italian tertiary referral center.

Liver biopsy is crucial for the diagnosis of autoimmune hepatitis (AIH), and new reproducible histological criteria would be highly desirable, especially in acute-on-chronic cases. The aims of the present study were (i) to evaluate the AIH histopathological criteria as a function of the time and modality of AIH onset, and (ii) to validate the count of apoptotic bodies in the portal tracts as a histopathological criterion for AIH diagnosis. Sixty-five patients were retrospectively enrolled: 20 underwent biopsy for the first diagnosis and 45 had a previous histological AIH diagnosis. Biopsies were revised, and all histological variables were collected, including the lymphocytic apoptotic bodies in the portal tracts. Clinical and serological data were revised as well. First-diagnosis patients showed a higher grade of inflammation (p = 0.001), but also worse portal fibrosis (p = 0.001). The apoptotic body count was higher in first-diagnosis patients than in follow-up patients (p = 0.002), and it was strongly correlated to inflammation. Using the apoptotic body count among the simplified AIH score variables, the first-biopsy patients in the "definite" category rose from 42 to 68%. Our results confirm the histopathological criteria proposed by the literature and introduce the count of portal apoptotic bodies for the diagnosis of active AIH, especially in first biopsies without other classic features, as well as in AIH diagnostic score, albeit future studies are required to find a definite cutoff.