Preoperative evaluation of malignancy in intraductal papillary mucinous neoplasms of the pancreas, especially in relation to dysplastic epithelial changes.

Background/aims: Intraductal papillary mucinous neoplasms have a better prognosis than ductal adenocarcinomas of the pancreas. The aim of this study was to evaluate the malignant potential of IPMNs by their preoperative images.

Methodology: Forty-three intraductal papillary mucinous neoplasms were divided into 3 duct ectatic types using preoperative images (the main duct type, the branch duct type, and the mixed type), and into 2 groups using resected specimens (the malignant group including severe dysplasia based on the WHO classification and the benign group). The diameters of the tumor, main pancreatic duct and mural nodule were measured on the images.

Results: Two thirds of main duct type cases were in the malignant group. For the branch duct and mixed types, the diameters of the tumor and detectable mural nodules were larger in the malignant group than in the benign group. A tumor diameter larger than 3.5cm and a mural nodule diameter larger than 6mm were risk factors for malignancy (p < 0.05).

Conclusions: The main duct type, a tumor larger than 3.5cm of the branch duct or mixed type, and a mural nodule larger than 6mm were all indicators of malignancy risk.