Intraductal Papillary Mucinous Neoplasms of the Pancreas: Clinicopathologic Characteristics and Long‐Term Follow‐Up After Resection

Abstract

Resection is recommended for main duct intraductal papillary mucinous neoplasms (IPMNs) of the pancreas because of the high risk of malignancy, but the indications for resection of branch duct and mixed-type IPMNs remain controversial. Our objective was to determine the appropriate management of IPMNs based on clinicopathologic characteristics and survival data obtained after resection. A total of 72 consecutive IPMN patients who underwent resection between January 1984 and June 2006 were reviewed. The lesions were classified as main duct, branch duct, or mixed-type IPMNs and histologically graded as noninvasive (adenoma, borderline neoplasm, carcinoma in situ) or invasive. Main duct IPMNs (n=15) were associated with a significantly worse prognosis than other subtypes. For branch duct (n=49) and mixed-type IPMNs (n=8), the diameter of the cystic lesions was an independent predictor of malignancy by multivariate analysis. However, four patients with cysts<30 mm in diameter and no mural nodules had a malignancy. No patient with noninvasive IPMN died of this disease, showing excellent survival, whereas the 5-year survival rate of patients with invasive IPMNs was only 57.6% and was significantly worse than that of patients with noninvasive IPMNs (p=0.0002). Resection of all main duct IPMNs seems to be reasonable. Invasive IPMNs were associated with significantly worse survival than noninvasive IPMNs. Although the diameter of cystic lesions was a predictor of malignancy for branch duct and mixed-type IPMNs, precise preoperative identification of malignancy was difficult. Therefore, these lesions should be managed by aggressive resection before invasion occurs to improve survival.