Granular cell tumor of the pancreas with chronic dilation of the main pancreatic duct.

Although a granular cell tumor (GCT) can originate in various locations, GCT of the pancreas is a rare entity. We herein report a case of GCT of the pancreas with chronic dilation of the main pancreatic duct (MPD). The patient had been referred to our institution for epigastric pain 12 years ago at 50 years old. Multidetector-row computed tomography (MDCT) had shown dilation of the MPD up to 8 mm in diameter from the pancreatic body to the tail. However, she had refused additional workup and been lost to follow-up. She was referred to our institution at 62 years old, as dilation of the MPD had been noted again. Imaging studies showed that the MPD had become dilated up to 33 mm from the pancreatic body to the tail. MDCT showed a hypovascular nodule (6 mm in diameter) in the pancreatic neck, and the nodule was located at the origin of MPD dilation. Pancreatic cancer was considered as a possible differential diagnosis. Surgical treatment was planned for a therapeutic diagnosis, and distal pancreatectomy with splenectomy and lymphadenectomy was performed. The gross findings of the resected specimen revealed a pale-yellow solid tumor measuring 8 mm in diameter at the pancreatic neck. The histopathologic assessment revealed the tumor to be GCT of the pancreas. The characteristics of GCT of the pancreas, such as a tumor causing stenosis and dilation of the MPD frequently and being too small to detect on imaging studies, may lead to a misleading diagnosis of pancreatic cancer.