Autoimmune pancreatitis and primary sclerosing cholangitis in a 16-year-old boy with inflammatory bowel disease.

Autoimmune pancreatitis (AIP) is a rare systemic fibroinflammatory disorder. The disease usually occurs in elderly men and offers an excellent response to steroid treatment. AIP in childhood is exceedingly rare. We report the first case of AIP in a boy with primary sclerosing cholangitis (PSC) and inflammatory bowel disease (IBD). He presented with a six-year history of intermittent bloody diarrhoea. Colonoscopy revealed severe pancolitis and ileitis in keeping with IBD. Abnormal liver function tests and magnetic resonance cholangiopancreatography (MRCP) findings confirmed PSC and subsequent occurrence of renal lesions and pancreatic abnormalities on computed tomography imaging were suspicious for AIP. Immunoglobulin G4 (IgG4) serum levels were elevated and treatment with steroids led to complete resolution of renal lesions, pancreatic changes and normalization of IgG4 and liver function tests. Follow-up MRCP 6 months later revealed unchanged biliary abnormalities in keeping with PSC. The differentiation between PSC and extrapancreatic AIP affecting the biliary tree and liver is critical given the dramatic response of AIP to steroids. Recent recommendations therefore include IgG4 measurement in every adult with possible PSC. Our case documents for the first time that AIP has to be considered as a differential diagnosis in childhood PSC. IgG4 measurement should be recommended universally in possible PSC.