Autoimmune pancreatitis should be differentiated from pancreatobiliary cancers because they often have similar clinical features and images. Accurate and practical diagnostic algorithm for AIP is important to avoid unnecessary surgery and delayed treatment. International Consensus Diagnostic Criteria for AIP suggested that diagnostic algorithms and the practical patterns considerably vary worldwide. Patients with clinically suspected AIP can be categorized into patients with typical features of AIP and patients with indeterminate features based on CT findings. Serology and other organ involvement can be used as collateral evidence of AIP. If a patient presents with diffuse pancreatic enlargement but is lack of collateral evidence, pancreatogram could be useful. If a patient has obstructive jaundice, biliary drainage and endobiliary biopsy are recommended. Duodenal papillary biopsy for IgG4 immunostain can be used during ERCP. In case of atypical imaging findings, EUS-guided FNA/biopsy is recommended to exclude pancreatic cancer and to obtain the suggestive findings of AIP. If type 2 is clinically suspected, EUS-guided core biopsy is required for the definite diagnosis. Short-term steroid trial can be performed to confirm the diagnosis of AIP when pancreatobiliary cancer workup shows negative results. However, clinical practice in diagnosing AIP varies depending on the local expertise, facilities, cost, prevalence of AIP and its subtypes.

• 이종균(성균관대학교 의과대학 삼성서울병원 내과학교실) | Jong Kyun Lee Corresponding author