自體免疫性胰臟炎是一種良性的慢性胰臟炎與自體免疫性疾病有關，期臨床影像、實驗室檢驗、及病理學上有其特殊的表現。我們報告一例67歲男性因為無痛性黃疸來急診求診，其本身已有一年多糖尿病的病史，腹部超音波顯示出一個在胰臟頭部4.0 x 3.3公分低迴音性的病兆，斷層掃描發現彌漫性胰臟腫大，尤其是胰臟頭部分；逆行性膽胰管攝影顯示主胰管呈現不規則狀瀰漫性狹小合併總膽管末端狹窄；內視鏡超音波則發現非均質性胰臟腫大和一個3.0 x 2.7公分相對低迴音性在胰臟頭部的病兆。因此請外科醫師做一個腹腔鏡的胰臟頭部與體部的組織切片，病理學顯示廣泛性淋巴球與漿胞球浸潤，並無癌細胞的發現；再加上血液中免疫球蛋白IgG4濃度超過160 mg/dL，因此本病例確診為自體免疫性胰臟炎。治療的首選為類固醇，此病患治療一年多後仍存活，其影像上及黃疸皆有改善，但糖尿病的控制並無改善。

Autoimmune pancreatitis (AIP) is a benign form of chronic pancreatitis that is associated withautoimmune processes demonstrated on clinical images, laboratory, and histopathologic features. Weherein report the case of a 67-year-old man with a history of diabetes mellitus for one year who wasreferred to our emergency department because of painless jaundice for 3 days. Abdominal computedtomography revealed diffuse but uniformly enhanced pancreatic enlargement, especially in the pancreatichead. On endoscopic retrograde cholangio-pancreatography, the main pancreatic duct had an irregularcontour and diffuse attenuation. There was also a stricture of the distal common bile duct. Endoscopicultrasound imaging showed a reticular pattern and diffuse enlargement of pancreatic parenchyma. Therewas a 3.0 x 2.7 cm relative hypoechoic lesion in the pancreatic head. Tissue diagnosis was made bylaparoscopic biopsy, which revealed abundant lymphoplasmacytic cell infiltrates accompanied by periductalinflammation by histopathology. The serum immunoglobulin G4 level was greater than 160 mg/dL. These findings led to a diagnosis of autoimmune pancreatitis for which the treatment of choice iscorticosteroids. Our patient was still alive and being treated with oral steroids one year later. The imagingand jaundice improved after treatment, however the pre-existing diabetes mellitus did not improve duringthe steroid therapy.