Histopathologic Findings of Multifocal Pancreatic Intraductal Papillary Mucinous Neoplasms on CT

OBJECTIVE. The criteria for resection of solitary pancreatic side-branch intraductal papillary mucinous neoplasm (IPMN) have been well described by the Sendai consensus statement. However, the management of multiple pancreatic cystic lesions is less certain, with no clear guidelines in the literature to date. The purpose of this study was to evaluate the histopathologic findings in pancreatic IPMNs in patients with multiple (>= 4) pancreatic cysts. MATERIALS AND METHODS. The CT scans of all patients with a pathologically proven IPMN at our institution were reviewed, and a total of 52 patients with four or more pancreatic cysts were found. Each case was reviewed for the number of cysts and the presence of signs of invasive malignancy including a coexistent solid pancreatic mass, pancreatic ductal dilatation, and mural nodularity. RESULTS. A total of 52 patients (19 men, 33 women; mean age, 71.8 years) were found to have multifocal IPMNs, defined as four or more cysts, on CT. Of these 52 patients, nine also had evidence of a solid pancreatic mass on CT. Retrospective review of the pathologic results for the remaining 43 patients (17 men, 26 women; mean age, 71.76 years) showed 18 cases of an IPMN with either high-grade dysplasia or a coexistent invasive carcinoma. Most important, 37% (7/19 patients) had no CT findings of an invasive malignancy according to the Sendai criteria (i.e., cysts >= 3 cm in the axial plane, main pancreatic ductal dilatation >= 6 mm, or mural nodularity within a cyst) but were found to have an IPMN with either high-grade dysplasia or invasive carcinoma. When the pancreas contained 10 or more cysts, high-grade dysplasia or invasive carcinoma tended to be more likely than low-or intermediate-grade dysplasia (odds ratio, 3.83; 95% CI, 0.87-16.8; p = 0.075). CONCLUSION. The presence of multiple pancreatic cysts should be looked on with suspicion, particularly when there are a large number of cysts, even when none of the cysts individually meet the imaging criteria for resection according to the Sendai consensus recommendations. At the very least, these patients need to be followed very closely.