Pancreatic Neuroendocrine Tumors and Intraductal Papillary Mucinous Neoplasm of the Pancreas: A Systematic Review.

Objectives This study aimed to identify factors that explain the association of intraductal papillary mucinous neoplasms-pancreatic neuroendocrine tumors (IPMNs-PNETs), radiological characteristics, and factors that might guide therapy. Methods We performed a systematic review of the literature to search for articles on concurrent IPMN-PNET, mixed endocrine-exocrine pancreatic tumors, and/or PNET with an intraductal growth pattern. Results A review of the literature suggests that there is some confusion about association of IPMNs-PNETs. Regarding this association, the studies collected data from 32 patients. Eleven patients presented concurrent tumors, 9 mixed endocrine-exocrine tumors, and no data were available in the remaining 7. In addition, the relationship IPMN-PNET focuses not only on the coexistence of the 2 lesions, but also on the possibility of the intraductal growth of the endocrine lesion. In the literature, in 4 cases, the preoperative radiological diagnosis had been IPMN. Conclusions Intraductal papillary mucinous neoplasms and PNETs may be associated in a number of scenarios. The association may be due to the concurrent existence of independent lesions, may be a mixed endocrine-exocrine tumor, or may be due to intraductal growth of the endocrine lesion. But the literature is confusing. It is not known whether the association is accidental or whether there is an etiological reason. Further studies are needed to investigate this scenario.