AIM:To compare clinicopathological features of acute presentation of type 1 autoimmune hepatitis(AIH) with or without centrilobular necrosis(CN).METHODS:Our study comprised 41 patients with biopsy-proven acute presentation(acute exacerbation phase 36,acute hepatitis phase 5) of type 1 AIH at our hospital from 1975 to 2009.Elevated serum alanine aminotransferase(ALT)(> 5x upper limit of normal) identified acute presentation of the disease.We compared clinicopathological features of these AIH patients with or without CN.The data used for analysis included patient background(age,sex,type of disease,presence of complications with other autoimmune diseases,human leukocyte antigen,and International Autoimmune Hepatitis Group score),clinical parameters at presentation(ALT,alkaline phosphatase,IgG,anti-nuclear antibodies,and anti-smooth muscle antibodies),histology and therapy.RESULTS:CN was found in 13(31.7%) patients with acute presentation(acute exacerbation phase 10,acute hepatitis phase 3) of AIH.Serum IgG levels of patients with CN were significantly lower than those of patients without CN(mean:2307 mg/dL vs 3126 mg/dL,P < 0.05),while antinuclear antibody-negative rates were significantly higher(30.7%vs 3.5%,P < 0.05).However,other clinical features were similar between the two groups.The frequency of advanced fibrosis in patients with CN was significantly lower than in patients without CN(F0-2:84.6% vs 35.7%,F3-4:15.4% vs 64.3%,P < 0.05).Other histological features were similar between the two groups.Although there was no significant difference between groups when evaluated using the revised original score(12 vs 14),the simplified AIH score of patients with CN was significantly lower(6 vs 7,P < 0.05).Frequency of DR4 was similar between patients with and without CN.CONCLUSION:CN is observed in both Japanese patients with acute hepatitis phase and acute exacerbation phase of type 1 AIH,although AIH with CN often shows clinical features of the genuine acute form. AIM: To compare clinicopathological features of acute presentation of type 1 autoimmune hepatitis (AIH) with or without centrilobular necrosis (CN) .METHODS: Our study comprised 41 patients with biopsy-proven acute presentation (acute exacerbation phase 36, acute hepatitis phase 5) of type 1 AIH at our hospital from 1975 to 2009. Elevated serum alanine aminotransferase (ALT) (> 5x upper limit of normal) identified acute presentation of the disease. We compared clinicopathological features of these AIH patients with or without CN. The data used for analysis included patient background (age, sex, type of disease, presence of complications with other autoimmune diseases, human leukocyte antigen, and International Autoimmune Hepatitis Group score), clinical parameters at presentation (ALT, alkaline phosphatase, IgG, anti-nuclear antibodies , and anti-smooth muscle antibodies), histology and therapy .RESULTS: CN was found in 13 (31.7%) patients with acute presentation (acute exacerbation phase 10, acute hepatitis phase 3 ) of AIH.Serum IgG levels of patients with CN were significantly lower than those of patients without CN (mean: 2307 mg / dL vs 3126 mg / dL, P <0.05) vs 3.5%, P <0.05) .However, the other clinical features were similar between the two groups. The frequency of advanced fibrosis in patients with CN was significantly lower than in patients without CN (F0-2: 84.6% vs 35.7%, F3 -4: 15.4% vs 64.3%, P <0.05). There was no significant difference between groups when evaluated as the revised original score (12 vs 14), the simplified AIH score of Patients with CN was significantly lower (6 vs 7, P <0.05). Frequency of DR4 was similar between patients with and without CN. CONCLUSION: CN is observed in both Japanese patients with acute hepatitis phase and acute exacerbation phase of type 1 AIH, although AIH with CN often shows clinical features of the genuine acute form.