Pancreatic Oncocytic Intraductal Papillary Mucinous Neoplasms: Three Case Reports and Review of Cases in Literature

Objectives Oncocytic intraductal papillary mucinous neoplasias represent a rare morphological subtype of intraductal papillary mucinous neoplasias, accounting for 1-8% of cases. Our aim was to characterize clinical factors associated with oncocytic intraductal papillary mucinous neoplasias, and factors that may predict invasive carcinoma. Methods Patient data for three consecutive cases of oncocytic intraductal papillary mucinous neoplasia were abstracted from electronic medical records. Literature search was performed using Pubmed and Google Scholar search engines using the keywords, "oncocytic intraductal papillary mucinous neoplasm," "oncocytic intraductal papillary mucinous neoplasia," "intraductal oncocytic papillary neoplasm," and "intraductal oncocytic papillary neoplasms." Studies that reported age, gender, invasiveness, and main versus branch duct involvement were included. Results We detailed three case reports and identified 77 previously published cases of oncocytic intraductal papillary mucinous neoplasia. The mean age at diagnosis was 61.6 years. There was a significant association of oncocytic intraductal papillary mucinous neoplasias with male gender (P= 0.03), but not with main/mixed versus branch duct involvement (P= 0.053). Invasive carcinoma was observed in 55.8% of oncocytic intraductal papillary mucinous neoplasias. In a subgroup of patients that underwent KRAS mutation testing (N= 25), 7(28%) harbored a KRAS mutation; KRAS mutation did not predict presence of invasive carcinoma (P= 1.00). Conclusions Clinical factors or KRAS mutation testing cannot currently predict the malignant potential of oncocytic intraductal papillary mucinous neoplasias. Management of oncocytic intraductal papillary mucinous neoplasias should still be based upon macroscopic criteria.