Oncocytic-Type Intraductal Papillary Mucinous Neoplasms: A Unique Malignant Pancreatic Tumor with Good Long-Term Prognosis

BACKGROUND: The different epithelial phenotypes of intraductal papillary mucinous neoplasms (IPMNs) are predictors of tumor biology and post-surgical outcomes. Oncocytic-type IPMN (O-IPMN) seems to have a unique natural history, but not much information is available because of its rarity. We sought to describe the characteristics of a cohort of patients resected for O-IPMNs, focusing on their long-term outcomes after surgery. STUDY DESIGN: We conducted a retrospective review of the demographics, clinical presentation, pathology, and survival of a cohort of patients resected for IPMN between 1990 and 2013, comparing O-IPMN with other IPMN subtypes. RESULTS: Eighteen of 400 patients (4.5%) who underwent resection for IPMN had the oncocytic subtype. Compared with other IPMN patients, those with O-IPMNs were more likely to be male (72% vs 45%; p = 0.02) and to have main pancreatic duct involvement (72% vs 42%; p = 0.01). Oncocytic IPMNs occurred in asymptomatic individuals in 67% of cases. They had either invasive carcinoma (61%) or high-grade dysplasia (39%), and the proportions in other epithelial subtypes were 19% and 21%, respectively (p < 0.001). After resection, the 10-year recurrence rate for O-IPMNs was 46%. Recurrences occurred up to 11 years after the initial resection and a completion total pancreatectomy was performed in 4 patients. At a median follow-up of 7 years, no patients with O-IPMN had died from the disease. CONCLUSIONS: Oncocytic IPMN is a unique tumor subtype that occurs mostly in the main pancreatic duct and is malignant. Recurrences after resection are not uncommon and can occur more than 10 years after the initial resection. Reoperations for recurrent O-IPMN are often feasible and have excellent results in terms of survival. (C) 2015 by the American College of Surgeons