Granular cell tumor of the pancreas diagnosed by endoscopic ultrasound-guided fine-needle aspiration.

A 68-year-old woman was referred to our hospital for the treatment of bile duct stone, pancreatic tumor, and pancreatic cysts. First, bile duct stone was removed using endoscopic retrograde cholangiopancreatography. By abdominal contrast-enhanced computed tomography, a 12-mm diameter tumor was found in the pancreatic body. The tumor was isodense compared with the surrounding pancreatic parenchyma in the non-contrast phase and poorly enhanced in the arterial phase; it exhibited gradual enhancement from the portal vein phase to the late phase. Numerous pancreatic cysts were also observed by contrast-enhanced computed tomography. By magnetic resonance imaging, the tumor was hypointense in T1-weighted images, isointense in T2-weighted images, and hyperintense in diffusion-weighted images. By magnetic resonance cholangiopancreatography, the main pancreatic duct was not dilated, and pancreatic cysts communicated with the main pancreatic duct. The pancreatic cysts were diagnosed as branch-type intraductal papillary mucinous neoplasm. Histopathologic assessment of the specimens obtained by endoscopic ultrasound-guided fine-needle aspiration revealed the tumor as benign pancreatic granular cell tumor. The patient was followed up without surgical resection. On contrast-enhanced computed tomography at 6 months after admission, the tumor did not show any changes in diameter or characteristics.