Determination of Malignancy Predictors in Branch Duct TypeIntraductal Papillary Mucinous Neoplasms of the Pancreas

ABSTRACT

PURPOSE: Branch duct type intraductal papillary mucinous neoplasms (Br-IPMN) have better prognosis and lower malignancy rate than do main duct type IPMNs (M-IPMN). However, surgical resection is necessary when malignancy is suspected, and radical resection should be performed in cases of invasive IPMN. The objectives of this study were to investigate the characteristics of Br-IPMN and related predictive malignancy/invasiveness factors and to present a standardized scoring system for predicting pathologic results. METHODS: We conducted a retrospective review of 91 patients diagnosed with Br-IPMNs between 1998 and 2007. Mean patient age was 62.5+/-9.0 years. Eighty (87.9%) patients had benign IPMNs (17 adenoma, 63 borderline malignancy), and 11 (12.1%) patients had malignant IPMNs (4 carcinoma in situ, 7 invasive carcinoma). Eighty-four (92.3%) patients had noninvasive IPMN, and 7 (7.7%) patients had invasive IPMN. RESULTS: The size of the cystic mass and the presence and size of the mural nodule were found by univariate analysis to be significantly different between the benign and malignant groups. History of DM, size of the cystic mass, size of the mural nodule, and thickness of the cystic wall were significantly different between the noninvasive and invasive IPMN groups on univariate analysis. The regression coefficients for the size of the cystic mass and for the size and presence of the mural nodule were calculated using multivariate analysis, and the scores predicting malignant and invasive IPMN determined (P=0.001, P=0.000, respectively). CONCLUSION: There are no universally held guidelines for surgical management of Br-IPMN patients. Hence, many clinicians have difficulty deciding the specific character of the resection they will pursue. By using malignancy- and invasiveness-predicting scores, we expect that much of this difficulty can be avoided in the future.