Intraductal papillary tumors of the pancreas: evaluation with endoscopic ultrasonography

Background: We retrospectively analyzed the endoscopic ultrasonographic characteristics of intraductal papillary tumors of the pancreas and identified signs indicative of malignant tumors. Methods: Twenty-eight patients with intraductal tumors and 38 with other pancreatic cystic lesions underwent endoscopic ultrasonography, conventional ultrasonography, and endoscopic retrograde cholangiopancreatography (ERCP). Results: Intraductal tumors were classified into three subtypes, and endoscopic ultrasonographic characteristics were assessed. In main duct type tumors, the main pancreatic duct showed a segmental or diffuse moderate-to-marked dilatation, often associated with intraductal nodules. Pancreatic parenchymal atrophy was frequently recognized. Branch duct type tumors consisted of multiple 5 to 20 mm cysts with the appearance of a cluster of grapes. The main duct was mildly dilated or nondilated. Combined type tumors had features of both main duct and branch duct types. Endoscopic ultrasonography (92%) differentiated pancreatic cystic lesions more precisely than ultrasonography (82%) and ERCP (89%). Main duct or combined type tumors, large tumors (greater than or equal to 30 mm for branch duct type), marked dilatation of the main pancreatic duct (greater than or equal to 10 mm for other types), and mural nodules suggested malignancy. Endoscopic ultrasonography demonstrated these signs more accurately than ultrasonography or ERCP. Conclusion: Endoscopic ultrasonography is useful for diagnosing intraductal papillary tumors, particularly for predicting malignancy.