Digital slide images of 20 IPMNs were independently assessed by 10 Japanese pathologists, who then held a consensus meeting to discuss the points of disagreement and develop a consensus and recommendations.
The average agreement rates for grade and type were 83.5% (range, 100%-40%) and 82.5% (range, 100%-50%) and the Fleiss\' κ values were 0.567 and 0.636, respectively.
The disagreement points and recommendations were as follows: destructed ductal walls with desquamated neoplastic epithelia or mucin lakes partially lined with neoplastic cells could be invasion; intraductal stromal invasion could be dismissed unless vascular or lymphatic invasion existed; elastica staining may help visualize ducts in colloidal nodules; high-grade can be distinguished from low/intermediate grade by marked nuclear disarrangements and complex architecture in the intestinal papillae; oncocytic papillae are characterized by eosinophilic cells with round disoriented nuclei; high-grade gastric papillae can be distinguished from pancreatobiliary papillae by relatively low but complex architecture; and the most dysplastic papillae should be used to assess type in mixed papillae types.