Preoperative evaluation of invasive and noninvasive intraductal papillary-mucinous neoplasms of the pancreas: clinical, radiological, and pathological analysis of 123 cases.

OBJECTIVE: We aimed to investigate preoperative findings that are useful to distinguish intraductal papillary-mucinous neoplasm (IPMN) subtypes.

METHODS: One hundred twenty-three patients who underwent pancreatectomy for IPMN were analyzed clinicopathologically and radiologically. Invasive IPM carcinomas (IPMCs) were subdivided into early-stage nonaggressive (minimally invasive IPMC [MI-IPMC]) and more advanced and aggressive (invasive carcinoma originating in IPMC [IC-IPMC]) subtypes according to our recently proposed pathological criteria.

RESULTS: The lesions consisted of 27 IPMNs with low-grade dysplasia, 14 IPMNs with moderate dysplasia, 21 IPMNs with high-grade dysplasia, 30 MI-IPMCs, and 31 IC-IPMCs. Multidetector-row computed tomography detected a component of invasive carcinoma in IC-IPMC with 86% sensitivity and 100% specificity. In patients with IPMNs other than IC-IPMC, multivariate analysis demonstrated 3 significant predictive factors of malignancy: IPMN size (>40 mm), IPMN duct type (main pancreatic duct or mixed type), and the presence of a mural nodule or thick septum. The diagnostic score obtained using these 3 factors showed a strong correlation with the presence of malignancy.

CONCLUSIONS: For preoperative evaluation of patients with IPMN, it is recommended to rule out IC-IPMC using multidetector-row computed tomography and then to categorize IPMN other than IC-IPMC according to malignant potential based on the diagnostic score.