A Case of Pancreatic Acinar Cell Carcinoma with Invasion of the Main Pancreatic Duct Treated by Total Pancreatectomy

We encountered a case of pancreatic acinar cell carcinoma (ACC), which is a somewhat rare clinical entity. The patient was a 78-year-old woman who had been examined elsewhere for persistent upper abdominal pain that had begun a few months earlier. The examination revealed a neoplastic lesion in the head and tail of the pancreas. Contrast-enhanced abdominal computed tomography revealed a tumor measuring 42 x 59 mm in the tail of the pancreas with distinct margins and internal heterogeneity. Furthermore, solid portions suggestive of invasion of the main pancreatic duct were seen. Endoscopic retrograde pancreatography was performed, and cytologic examination of the pancreatic fluid led to a diagnosis of class V carcinoma. The tumor was located mainly in the pancreatic tail, but the ductal invasion extended into the pancreatic head. Thus, we performed radical total pancreatectomy. Histopathologic examination revealed proliferation of tumor cells with eosino‐ philic cell bodies as the main intraductal component, whereas the primary tumor comprised adenoid, cribriform, and solid structures. Upon immunohistochemical staining, the cells tested positive for Bcl-1 and negative for synaptophysin and chromogranin A, so pancreatic ACC was diagnosed (pT2N0M0-fStageIB). Pancreatic acinar cell carcinoma accounts for 0.4% of all pancreatic cancers in Japan, and invasion of the main pancreatic duct is rare.