S. M. Wcislak1, Z. E. Stiles1, J. L. Deneve1, E. S. Glazer1, S. W. Behrman1, M. Ismail2, F. T. Farees3, P. V. Dickson1 1University Of Tennessee Health Science Center,Division Of Surgical Oncology, Department Of Surgery,Memphis, TN, USA 2University Of Tennessee Health Science Center,Division Of Gastroenterology, Department Of Medicine,Memphis, TN, USA 3Gastro One,Gasteroenterology,Memphis, TN, USA
Introduction: Although pancreatic neuroendocrine tumors (PNETs) typically have a solid, hypervascular appearance on contrast-enhanced imaging, other non-PNET lesions may have a similar appearance. Preoperative recognition of non-PNET diagnoses may alter further staging and treatment plans.
Methods: Patients from our institutional pancreatic surgery database who underwent pancreatectomy for suspected PNET were identified. Demographics as well as results of pre-operative contrast-enhanced CT and/or MRI, endoscopic ultrasound-fine needle aspiration (EUS-FNA), and pathology data were collected. Patients with documented distant metastases, functional tumors, and hereditary PNET syndromes were excluded.
Results: From 2007-2017, 55 patients with pre-operative contrast-enhanced CT and/or MRI had pancreatectomy for a suspected diagnosis of sporadic, localized, non-functional PNET. Final pathology revealed PNET in 42 (76%) and a non-PNET diagnosis in 13 (24%). Of patients with a diagnosis of PNET, the lesion on CT/MRI was solid in 31 (74%) and cystic in 11 (26%). Solid PNETs were hypervascular in 26 (84%), hypodense in 4 (13%), and isodense in 1(3%) on contrast-enhanced imaging. Hypervascular solid lesions were appreciated in 13 non-PNET patients with a final diagnosis of intrapancreatic splenule (4), metastatic renal cell carcinoma (2), solid pseudopapillary tumor (2), serous cystadenoma (1), duodenal GIST (1), adenocarcinoma (1), focal pancreatitis (1), and no tumor present (1). There were no significant differences in age, gender, race, tumor size, tumor location, pancreatic or biliary duct dilation, or contrast enhancement patterns (homogenous vs heterogeneous) between patients with PNET vs non-PNET diagnoses. Patients with a non-PNET diagnosis on final pathology were significantly less likely to have undergone EUS-FNA than patients with a final diagnosis of PNET (15% vs 79%, p<0.001). EUS-FNA was found to have a sensitivity of 79%. Accurate pre-operative diagnosis would have spared pancreatectomy in 7(13%) patients with benign pathology and may have altered the staging or preoperative treatment plan in 4(7%) with non-PNET malignancies.
Conclusion: Although typically hypervascular, PNETs may appear isodense, hypodense, or cystic on contrast-enhanced imaging. Importantly, a number of other benign and malignant non-PNET diagnoses may have a solid, hypervascular appearance. EUS-FNA and additional diagnostic modalities should be routinely performed to confirm a diagnosis prior to pancreatectomy.