Pancreatic cyst as a sentinel of in situ carcinoma of the pancreas: Report of two cases

Conclusion. We would like to recommend detailed examination of the pancreas including cytology of the pancreatic juice in patients with pancreatic cyst to find possible concomitant early pancreatic carcinoma. Further study is necessary to determine whether there is a rational relationship between mucinous cystadenoma of the pancreas and pancreatic adenocarcinoma. Background. Two cases of in situ carcinoma of the pancreas first detected with pancreatic cyst as a diagnostic clue are reported. Cytologic examination of the pancreatic juice was positive for malignancy in both cases, and pancreatic cyst and in situ carcinoma were located independently. Methods and Results. Case 1: Ultrasonography (US) and computed tomography (CT) in a 54-yr-old Japanese man with a known gastric cancer revealed a pancreatic cyst. Endoscopic retrograde cholangiopancreatography (ERCP) showed a cyst in the tail of the pancreas, and cytology of the pure pancreatic juice revealed adenocarcinoma. Intraoperatively, the pancreas was cut along the portal vein, and cytology of the pancreatic juice from the pancreas distal to the cutting line showed adenocarcinoma. Resection of the body and tail of the pancreas was performed together with total gastrectomy. Histopathologically, the cyst was mucinous cystadenoma, and the surrounding pancreatic ducts and ductules showed epithelial dysplasia of moderate-to- severe degree having foci of unequivocal in situ carcinoma. No stromal invasion was seen. Case 2: A 55-yr-old Japanese man with known hepatocellular carcinoma was diagnosed as having pancreatic cyst in the tail of the pancreas on US and CT. ERCP showed a pancreatic cyst, and cytology of the pancreatic juice highly suggested adenocarcinoma. Distal pancreatectomy and splenectomy were performed. Histopathologic diagnosis of pancreatic cyst was mucinous cystadenoma. The pancreatic ductule 2 cm proximal to the pancreatic cyst showed carcinoma in situ. The diagnostic clue of in situ carcinoma of the pancreas in these two cases was a cystic lesion of the pancreas detected by check-up US and CT of known carcinoma of the stomach and liver. Cytology of the pancreatic juice was also positive for malignancy. In situ carcinoma of the pancreas was found to be independent of the cysts because of the different locations and divergent histopathologic natures of the two lesions.