Pancreatic neuroendocrine tumors among patients with intraductal papillary mucinous neoplasms: real association or just a coincidence?

CONTEXT Intraductal papillary mucinous neoplasms (IPMNs) are being recognized with increased frequency and are the most common indication of pancreatic surgery at specialized centers. Many IPMN patients are found to have non-IPMN related pancreatic tumors like pancreatic neuroendocrine tumors (PNTs). OBJECTIVE To study the prevalence of PNTs among patients with IPMN. METHODS Patients who underwent surgical resection for IPMN were retrospectively reviewed for presence of histologically proven PNTs. The PNTs were evaluated for the patient demographics, imaging characteristics, histology, and surgical staging. RESULTS Between January 2002 and October 2007, 104 patients underwent surgery for pancreatic IPMN. Among these, 4 patients (3.8%) were diagnosed with concomitant PNTs (1 male, 3 females; median age 72 years). Three patients had branch duct type-IPMN (cyst size: 19 mm, 15 mm and 27 mm), and one had main duct type-IPMN. Only one branch duct IPMN had adenocarcinoma, other three had low grade/borderline dysplasia. The median size of PNT was 10 mm (range 8-16 mm) and all were missed on the cross sectional imaging. Three patients were recognized by endoscopic ultrasound (EUS) and the fine needle aspiration confirmed the diagnosis in 1/3. Only one patient had metastatic PNT to lymph node, the other three were low grade lesions. CONCLUSION IPMN and PNT can coexist. The prevalence of PNT among IPMN patients is low (3.8%). Our study is limited by small sample size. Large studies with large number of patients are needed to further explore this association.