Onset of autoimmune hepatitis in children and adolescents considering disease phenotypes

Background. Autoimmune hepatitis (AIH) in children is a rare but severe condition often associated with rapid progression of fibrosis and the development of cirrhosis. The diversity of phenotypic presentations complicates timely diagnosis and delays the initiation of treatment. The study aimed to analyze the patterns of AIH onset in children and adolescents, considering its phenotypes. ­Materials and methods. This retrospective study analyzed data from 132 children with AIH classified into four phenotypes: AIH-1, ­AIH-2, seronegative AIH (SN-AIH), and autoimmune sclerosing cholangitis (ASC). Clinical, laboratory, and immunological features of the onset, diagnostic timelines, and comorbidities were assessed. Results. AIH most often began as acute hepatitis with jaundice (53 %) or with a subclinical course (28 %). Fibrosis stages 3–4 affected 73 % of children, and 26 % had cirrhosis. AIH-1 (56 %) was characterized by antinuclear antibody positivity (80 %), immunoglobulin G > upper limit of normal (ULN) (66 %), and acute hepatitis (alanine aminotransferase (ALT) > 10 ULN in 66 % of cases). AIH-2 (9 %) was characterized by the presence of anti-LKM1 (87.5 %) and anti-LC1 (75 %), with immunoglobulin G > ULN in 42 % and IgA deficiency in 8 % of children. ASC (29 %) was associated with inflammatory bowel disease (68 %) and the highest gamma-glutamyl transferase/aspartate aminotransferase ratio (0.8). SN-AIH (6 %) was characterized by the absence of autoantibo­dies, less significant cytolysis (ALT > 10 ULN in 25 %), and comorbidity with juvenile idiopa­thic arthritis in 25 % of cases. Diagnostic search averaged 3 months (interquartile range 1–7) for ­AIH-1, while for AIH-2, ASC, and ­SN-AIH, it required 12–15 months, with delays exceeding 2 years in 50, 24, and 37 % of cases, respectively. ­Conclusions. ­AIH-2, ASC, and SN-AIH phenotypes exhibit nonspecific clinical and laboratory features, which complicate their timely diagnosis and treatment that is crucial for disease prognosis.