A case of small pancreatic acinar cell carcinoma detected by endoscopic ultrasonography (EUS)

Abstract

A 53-year old man was first hospitalized to our hospital due to a severe abdominal pain on October 3, 2006. Acute pancreatitis possibly due to alcoholic drinking was diagnosed on an abdominal CT revealing the swollen pancreatic tail, peri-pancreatic fluid collection and pleural effusion. Magnetic resonance cholangio-pancreatography showed no abnormality of the main pancreatic duct (MPD). His hospital course was satisfactory and discharged 2weeks later, but he could not quit alcohol intake. He was second hospitalized due to acute pancreatitis on January 13, 2007, when CT showed slight dilatation of the MPD (3 mm) in the pancreatic body to tail without any space occupying lesions. After intermission of 6 months, he was third hospitalized due to the same reason, when CT showed ill-defined hypo-perfusion mass of 1cm at diameter with distal MPD dilatation suggesting MPD obstruction at the pancreatic body. Although radiologist interpreted this lesion as cystic dilatation of the pancreatic branch, we performed EUS to examine the reason of MPD obstruction. EUS defined a low echoic mass lesion of 10 mm at diameter slightly enhanced after the injection of the contrast material (Levovist). Intraductal ultrasonography (IDUS) for MPD showed an irregular low echoic mass adjacent to MPD. The result of endoscopical pancreatic biopsy was atypical cell proliferation showing glandular or solid pattern with high cellurality, suggesting acinar cell carcinoma. Distal pancreatectomy was performed on October 3, 2007. Small nodular lesion of 10×6 mm in the pancreatic body was histologically and immunohistochemically acinar cell carcinoma with slight venular/peineural and lymphatic permeations. There is no recurrence so far. We emphasize the importance of EUS and IDUS to identify small pancreatic tumor.