Diagnosis of autoimmune pancreatitis using endoscopic ultrasonography

Background  Revised clinical criteria for autoimmune pancreatitis (AIP) have been proposed by the Research Committee of Intractable Disease of the Pancreas and the Japan Pancreas Society. These criteria require distinguishing AIP from neoplastic lesions. However, this can be difficult, and patients often undergo surgery on the basis of suspected pancreatic cancer (PC). Methods  AIP was diagnosed in 25 patients at the Aichi Cancer Center Hospital (ACCH) according to the revised AIP criteria. In each patient, endoscopic ultrasonography (EUS) was used to describe the conventional pancreatic parenchymal and ductal features of chronic pancreatitis (Sahai criteria), and other abnormal features, namely, diffuse hypoechoic areas (DHAs), diffuse enlargement (DE), focal hypoechoic areas (FHAs), focal enlargement, bile duct wall thickening (BWT), lymphadenopathy, and peripancreatic hypoechoic margins (PHMs). We compared these features between 25 patients with AIP and 30 patients with pancreatic cancer resected at ACCH. Results  Few conventional EUS features of chronic pancreatitis (CP) were seen in patients with AIP (mean, 2.0 features). Frequencies of DHA, DE, BWT, and PHM were significantly higher in AIP than in PC. DHAs, DE, and FHAs resolved after steroid treatment. Conclusions  Novel EUS features of AIP are useful in distinguishing AIP from PC and for following the effects of steroid therapy.