Endoscopic Ultrasonography‐Guided Fine Needle Aspiration Can Be Used to Rule Out Malignancy in Autoimmune Pancreatitis Patients

OBJECTIVES: The aim of this study was to review the suitability of endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA) for ruling out malignancy in autoimmune pancreatitis patients. METHODS: We retrospectively reviewed 40 autoimmune pancreatitis patients (type 1:37 patients; type 2: two patients; possible autoimmune pancreatitis: one patient) who received EUS-FNA. Among the 40 autoimmune pancreatitis patients, 34 were not histopathologically diagnosed with autoimmune pancreatitis by EUS-FNA, and they were followed up for more than 6 months in our hospital. Moreover, 14 pancreatic cancer patients who were not diagnosed by EUS-FNA were selected as a control group. These 14 patients constituted 3.9% of the 360 pancreatic cancer patients who received EUS-FNA. We evaluated the prognoses of the 34 autoimmune pancreatitis patients and the clinical differences between these 34 autoimmune pancreatitis patients and the 14 pancreatic cancer patients. RESULTS: All 34 autoimmune pancreatitis patients showed reduced pancreatic swelling. The main pancreatic duct dilation ( > 3 mm), the diameter of the main pancreatic duct, the capsule-like rim sign, and serum CA19-9 levels were significantly different between the autoimmune pancreatitis and pancreatic cancer patients (2.9% versus 69.2%, P < .01; 1.7 ± 1.6 mm versus 6.8 ± 5.0 mm, P < .01; 79.4% versus 0%, P < .01; 41.4 ± 79.0 U/mL versus 2079.1 ± 275.3 U/mL, P = .02). CONCLUSIONS: Almost all pancreatic cancers can be diagnosed by EUS-FNA. Furthermore, other clinical characteristics of pancreatic cancer undiagnosed by EUS-FNA were different from autoimmune pancreatitis undiagnosed by EUS-FNA. Endoscopic ultrasonography-guided FNA can be used to rule out malignancy in autoimmune pancreatitis patients.