A 62-year-old male patient was referred to our hospital because of multiple pancreatic mass lesions. Contrast-enhanced computed tomography revealed multiple hypovascular lesions in the pancreas. Endoscopic ultrasonography revealed vague boundary, low echoic multiple mass lesions, and a duct-penetrating sign. We performed endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA). Histopathological examination revealed a typical lymphoplasmatic sclerosing pancreatitis. Subsequently, we made a diagnosis of multifocal type 1 autoimmune pancreatitis (AIP). After corticosteroid administration, the multiple mass lesions in the pancreas and kidney completely disappeared. AIP is difficult to distinguish from other diseases when it shows multifocal mass lesions in the pancreas. A comprehensive diagnosis is needed on the basis of other organ involvements, serum IgG4 level, and pathological findings from EUS-FNA.
