Patients with a resected pancreatic mucinous cystic neoplasm have a better prognosis than patients with an intraductal papillary mucinous neoplasm: A large single institution series.

BACKGROUND/OBJECTIVES: Mucinous cystic neoplasms (MCNs) are rare pancreas tumors distinguished from intraductal papillary mucinous neoplasms (IPMNs) by the presence of ovarian-type stroma. Historical outcomes for MCNs vary due to previously ambiguous diagnostic criteria resulting in confusion with IPMNs. This study seeks to characterize and clarify the clinical features and long-term outcomes of MCNs versus IPMNs in the largest single-institution series of pathology-confirmed MCNs to date.

METHODS: We compared 142 MCNs and 746 IPMNs resected at a single institution. MCNs were reviewed for confirmation of ovarian-type stroma and reclassified according to current WHO guidelines.

RESULTS: MCNs presented almost exclusively in middle-aged women (median 47.5 years, 96.5% female) as solitary (100%), macrocystic (94.2%) lesions in the distal pancreas (92.1%). IPMNs were distributed equally by sex in an older population (median 69.0 years, 49.6% female) and favored the proximal pancreas (67.6%). Compared with IPMNs, MCNs were larger (4.2 cm vs 2.5 cm) and more often low-grade (71.1% vs 13.8%). Associated invasive carcinoma was less common in MCNs than in IPMNs (9.9% vs 32.4%). Surgical resection was curative for 100% of noninvasive MCNs. Patients with an MCN-associated invasive carcinoma had a much better prognosis than did patients with an IPMN-associated invasive carcinoma with 10-year disease-specific survival of 79.6% versus 27.2%, respectively.

CONCLUSION: MCNs have a stereotypical clinical profile that is readily distinguishable from IPMNs based on demographic features, imaging, and pathology. Most MCNs are noninvasive and curable with surgical resection. Prognosis remains excellent even for invasive disease with 10-year survival approaching 80% following resection.