Abstract: Objective The aim of this study was to investigate the clinical and pathological characteristics of immunoglobulin G4-associated autoimmune hepatitis (IgG4-AIH) in children. Methods 38 children with AIH were enrolled in our hospital between June 2014 and June 2019, and the diagnostic criteria was based on the simplified diagnostic scoring system reported by the International Autoimmune Hepatitis Group (IAIHG) in 2008 or the AIH diagnostic scoring system established by IAIHG in 1999. According to Umemura et al and other scholars’s reports, IgG4-AIH was diagnosed by hepatic IgG4 positive plasma cell infiltration≥10/ high power field of vision (HPF) and serum IgG4≥135 mg/dl. Serum IgG and IgG4 levels were detected by ELISA, and liver biopsies were performed routinely. The hepatic IgG4 positive plasma cell infiltration was evaluated by immunohistochemical staining. Results Out of the 38 patients with AIH included, four were diagnosed as IgG4-AIH and thirty-four were classical AIH; serum IgG and IgG4 levels in patients with IgG4-AIH were 22.6(13.2, 29.8)mg/dL and 226.5(105.8, 424.6)mg/dL, not significantly different as compared to 18.9(10.4, 25.3)mg/dL and 209.4(96.1, 401.6)mg/dL in patients with AIH (P>0.05); the hepatic IgG4 positive plasma cell infiltration in patients with IgG4-AIH were 40.2(25.4, 55.7)/HPF, significantly higher than in patients with AIH; the hepatic IgG4 positive plasma cell infiltration in patients with IgG4-AIH were positively correlated to histological activity index (r=0.48)and liver fibrosis staging(r=0.37, P<0.05); the returning to normal time for serum ALT in patients with IgG4-AIH was (3.5±0.8)w, significantly shorter than in patients with AIH, the returning to normal time for serum AST level was (3.6±0.6)w, much shorter than , for ALP was (4.0±1.1)w, much shorter than , for GGT was(4.2±1.5)w, significantly shorter than , and for serum IgG back to normal was (7.6±2.8)w, also much shorter than in patients with AIH. Conclusions Children with IgG4-AIH have the same as serum IgG4 levels in kits with AIH, while the infiltration of IgG4 positive plasma cells in liver tissues is significantly higher than that in children with AIH. In addition, the children with IgG4-AIH have a good therapeutic response to hormone therapy, and the recovery times of serological indexes are much quick. Our findings should be validated by multi-central studies because of too little cases with IgG4-AIH in our study.

Key words: Autoimmune hepatitis, Immunoglobulin G4-associated autoimmune hepatitis, Immunoglobulin G4, Clinical feature