Small invasive ductal carcinoma of the pancreas distinct from branch duct intraductal papillary mucinous neoplasm.

Endoscopic ultrasonography (EUS) is a highly sensitive diagnostic method for the detection of small pancreatic carcinomas. Recently, there have been some reports describing the utility of contrast-enhanced harmonic EUS (CEH-EUS) which uses sonographic contrast agent for differentiation of a pancreatic mass. This report describes a case of small adenocarcinoma of the pancreas distinct from branch duct intraductal papillary mucinous neoplasm (IPMN) in which investigation by EUS took place every 6 mo and diagnosis was made accurately by additional CEH-EUS during the follow-up of the branch duct IPMN. A 68-year-old female was admitted to our hospital because of a branch duct IPMN in the pancreatic body. She had been followed-up by EUS every 6 mo. However, after 2 years EUS demonstrated a low echoic area distinct from the branch duct IPMN which was vaguely discernible by EUS, and accurate sizing and differential diagnosis were considered difficult on the EUS imaging. CH-EUS with Sonazoid revealed a hypovascular tumor and we suspected small pancreatic carcinoma. The histopathological diagnosis was adenocarcinoma (10 mm) in the pancreatic tail, distinct from the branch duct IPMN of the pancreatic body. EUS and CEH-EUS may play an important role in the correct diagnosis of small pancreatic tumors, including synchronous and metachronous occurrence of IPMN and ductal adenocarcinoma of the pancreas.