Autoimmune pancreatitis in children: Clinical and imaging characteristics in a large patient sample.

OBJECTIVE: To describe clinical and imaging findings of a large sample of children with autoimmune pancreatitis (AIP). METHODS: We retrospectively reviewed medical records for patients with clinical features consistent with AIP from January 2009 to August 2023. Demographic, clinical, and histological findings on initial presentation were recorded. Imaging within 90 days of diagnosis was reviewed by a board-certified pediatric radiologist. RESULTS: Forty patients were included. Mean age was 12.9 years and 23 (57.5%) were female. AIP diagnosis was based on imaging in 87.5% (35/40), only one patient (2.5%) had all three diagnostic features (imaging, biopsy, immunoglobulin G4 [IgG4]). Two diagnostic features were present in 27.5% (11/40) of patients (15% imaging & IgG4, 12.5% imaging and biopsy). Gamma-glutamyl transferase (GGT) elevation was present in 62.5% (20/32) of patients and elevated direct bilirubin was present in 44% (11/25). Magnetic resonance imaging (MRI) was the most common imaging modality (75% of patients, 30/40) and the most common finding was pancreas T1-weighted hypointensity (90%, 26/29). Inflammatory bowel disease or another autoimmune condition was ultimately diagnosed in 42.5% of patients (17/40). Most patients (79%, 31/39) were treated with steroids over a 2-3-month period, resulting in symptom resolution in 87% (26/30). CONCLUSION: In 40 patients with features of AIP, most were diagnosed by imaging. A modest elevation of GGT and direct bilirubin in the absence of cholelithiasis might suggest AIP in the appropriate clinical context and should prompt consideration of MRI for diagnosis, followed by proper treatment.