[Unusual presentation of autoimmune pancreatitis type 1]

A-51-year-old man presented with increasingly severe upper abdominal pain, in reduced general state and mild weight loss. Ten years before the patient had undergone a Kausch-Whipple procedure (pancreaticoduodenectomy) for an inflammatory mass in the pancreas, at that time histologically identified as an inflammatory tumour with chronic pancreatitis. Since then he has had repeated episodes of stenosis of the biliary-digestive anastomosis, associated with acute cholangitis. Laboratory findings on admission revealed liver function tests that were moderately (AST, ALT) or markedly elevated (GGT and AP).

Abdominal ultrasound revealed cuffing of the portal vein and its side-branches with low echogenicity. Magnetic resonance imaging showed periportal edema with irregular bile ducts. Initially the histological examination strongly suggested a peripheral malignant T-cell lymphoma. However, subsequent examination revealed a chronic IgG4-associated, lymphoplasmatic sclerosing inflammation of the biliary tract.

Histological re-examination of the 10-year-old pancreatic resection specimens also showed severe lymphoplasmatic infiltrates suggesting a pancreatic manifestation of an IgG4-associated systemic disease (ISD), known nowadays as an type 1 autoimmune pancreatitis (AIP). Based on the initial diagnosis of an invasive periphere malignant T-cell lymphoma of the liver a pre-phase treatment with vincristine, prednisolone followed by one cycle of CHOEP were administered. This resulted in complete remission of the patient's symptoms. Once the true diagnosis had been revised this treatment was immediately stopped. Since the patient remained symptom-free, the initially elevated laboratory parameters returned to normal and a remission of low echogenicity cuffing of the portal vein was observed and no further steroid treatment was administered. Ursodesocycholic acid was then given as the only drug, to prevent any further episodes of cholangitis.

Autoimmune pancreatitis continues to be frequently unrecognized in clinical practice. But because it responds well to corticosteroids, this clinical entity should be considered in the differential diagnosis of unclear inflammatory changes and strictures of the pancreatic and biliary tracts or even, if necessary, looked for retrospectively in resected pancreas specimens.