Intraductal papillary-mucinous tumors of the pancreas: Differential diagnosis between benign and malignant tumors by endoscopic ultrasonography

OBJECTIVES: Recently, intraductal papillary-mucinous tumor (IPMT) of the pa ncreas has increasingly been recognized. However, differential diagnosis be tween benign and malignant IPMT is often difficult using conventional imagi ng modalities. The purpose of this study was to retrospectively investigate the value of endoscopic ultrasonography (EUS) for differentiating malignan t from benign IPMT. METHODS: A total of 51 patients with IPMT were preoperatively examined by E US. The endosonograhic findings were compared with histopathological findin gs of the resected specimens. RESULTS: In main duct type IPMT, the diameter of the main pancreatic duct ( MPD) was greater than or equal to 10 mm in seven of the eight malignant tum ors, compared with two of the seven benign tumors (p < 0.05). In branch duc t type IPMT, three of the four large tumors (> 40 mm) with irregular thick septa were malignant lesions. In both main duct type IPMT and branch duct I PMT, eight patients had large mural nodules (> 10 mm); seven of the eight t umors were malignant and one of the eight tumors was benign. When the tumor was diagnosed as malignant according to above three findings, EUS was able to differentiate between malignant and benign IPMT with an accuracy of 86% . CONCLUSIONS: Main duct type tumors with greater than or equal to 10 mm dila ted MPD, branch duct type tumors (>40 mm) with irregular septa, and large m ural nodules (>10 mm) strongly suggest malignancy on EUS. EUS would be a us eful modality for differentiating between benign and malignant IPMT. (C) 20 01 by Am. Cell. of Gastroenterology.