BackgroundAutoimmune liver disease (AILD) encompasses autoimmune hepatitis (AIH), autoimmune sclerosing cholangitis (ASC) and primary sclerosing cholangitis (PSC). A unified disease process evolving over time through these entities has been recently suggested. From this perspective, this study aimed to compare the characteristics of childhood-onset AILD at baseline and after a medium-to-long term follow-up period. MethodsPaediatric-onset cases of AILD diagnosed between 1992 and 2023 at a tertiary-care centre were reviewed. Patients transitioned to adult-care by the time of data collection were asked for clinical updates. ResultsFifty-five patients were included (AIH = 20, ASC =22, PSC =13). AIH, ASC and PSC exhibited increasing age at the onset (AIH to PSC, p < 0.01). The area under the receiver operating characteristic curve for gamma-glutamyltranspeptidase (GGT) combined with alkaline phosphatase/aspartate aminotransferase (ALP/AST) ratio in predicting sclerosing cholangitis was 0.94, with a sensitivity of 86 % and a specificity of 94 %. At the last follow-up (median duration 5,8 years, interquartile range [IQR] 2,9–10,2, n = 45), 15 patients (33 %) developed portal hypertension, 2 patients (4 %) underwent liver transplantation, no patient died. ConclusionA cohort of childhood-onset AILD managed at a single centre reveals a temporal trend in the onset of AIH, ASC and PSC, with progressively older ages. Elevated GGT levels combined with a high ALP/AST ratio predict the diagnosis of sclerosing cholangitis. The occurrence of liver-related adverse events in one-third of patients highlights the progressive nature of paediatric-onset AILD.