Usefulness of EUS-guided fine needle aspiration (EUS-FNA) in the diagnosis of functioning neuroendocrine tumors

Background: Localization of neuroendocrine tumors may be challenging. The role of EUS-FNA in this setting is unknown. Methods: Ten patients with clinically suspected functioning neuroendocrine tumors (hormonal disturbances) underwent EUS-FNA to determine the location and to confirm the diagnosis cytologically. Observations: EUS identified 14 tumors in these 10 patients. In all but one patient CT did not demonstrate the tumor or missed at least one of multiple lesions. Mean tumor size was 12 mm (range 4-25 mm). Tumor locations were pancreas (n = 13) and duodenal wall (n = 1). Eleven of the 14 detected lesions were aspirated under EUS with accurate diagnosis in all cases. Surgical confirmation of EUS-FNA findings was available in 7 patients. There was no complication of EUS-FNA. Conclusions: EUS is a highly accurate technique for visualization of small functioning neuroendocrine tumors not evident on CT and for identification of patients with multiple lesions. EUS-FNA safely provides cytologic confirmation with high accuracy in these patients.