Synopsis
Distinguish autoimmune pancreatitis from pancreatic and biliary malignancy, recognise its systemic phenotypes, and use specialist-led immunosuppression while monitoring relapse, diabetes, obstruction and exocrine failure.
- Autoimmune pancreatitis is a fibro-inflammatory pancreatic disorder: type 1 usually belongs to IgG4-related disease, whereas type 2 is not typically IgG4-driven and is associated with inflammatory bowel disease.
- Painless obstructive jaundice, diffuse or focal pancreatic enlargement and duct narrowing can closely imitate pancreatic adenocarcinoma; diagnostic confidence must come from converging evidence.
- A raised serum IgG4 supports type 1 disease but lacks adequate specificity to exclude cancer, and a normal result does not rule out type 2 autoimmune pancreatitis.
- Cross-sectional imaging should assess the pancreas, biliary tree, vessels, nodes and other organs; focal disease or atypical features usually require endoscopic ultrasound and specialist tissue review.
- Never use an informal steroid trial as the first diagnostic test for a pancreatic mass because transient improvement can delay definitive cancer diagnosis.
- Corticosteroid induction often produces rapid biochemical and radiological improvement, but initiation, tapering and response checks belong in an experienced pancreatobiliary service.
- Type 1 disease may involve bile ducts, salivary or lacrimal glands, kidneys, retroperitoneum, lymph nodes, lungs and aorta; examination should extend beyond the pancreas.
- Long-term follow-up addresses relapse, biliary strictures, glucocorticoid harm, pancreatic exocrine insufficiency and diabetes rather than ending when jaundice resolves.
Key red flags
Fever, rigors, hypotension or confusion with jaundice indicates possible infected biliary obstruction and requires emergency antibiotics plus source-control planning.
Progressive focal mass enlargement, vascular invasion, metastases or substantial unexplained weight loss must keep pancreatic malignancy at the forefront despite elevated IgG4.
New visual symptoms, focal neurology, chest pain or renal deterioration may signal serious extra-pancreatic IgG4-related organ involvement needing urgent specialist assessment.
Severe hyperglycaemia, ketones, dehydration or reduced consciousness after starting corticosteroids requires immediate diabetes evaluation and acute treatment.
Worsening symptoms during a presumed steroid response should prompt diagnostic reset, repeat imaging and tissue review rather than automatic immunosuppression escalation.
Investigation priorities
Define pancreatic morphology, duct strictures, biliary obstruction, vascular involvement and distant abnormalities.
Management branches
Imaging suggests autoimmune pancreatitis but pancreatic or biliary cancer remains possible.
- Stabilise cholangitis, organ failure or severe obstruction first, using urgent biliary expertise when source control is needed.
- Acquire pancreatic-protocol imaging and review prior scans for evolution, duct configuration, metastases and other-organ manifestations.
- Discuss serology, endoscopic sampling and pathology in a specialist pancreatobiliary MDT before exposing a potentially resectable cancer to steroids.
- Record which diagnostic domains support autoimmune disease, which contradict it and exactly how response will be checked if treatment proceeds.