Endoscopic ultrasound-guided fine-needle aspiration cytology of pancreatic neuroendocrine tumors - A study of 46 cases

BACKGROUND. Neuroendocrine tumors (NETs) of the pancreas are relatively uncommon tumors. The objective of this report was to describe the cytopathologic and immunocytochemical features of NETs obtained by endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA). METHODS. Forty-eight patients who were diagnosed with pancreatic NETs based on EUS-guided FNA were studied retrospectively (from 2002 to 2007). Clinical data, EUS findings, cytopathologic features, and immunocytochemical stains were reviewed for this study. The final histopathologic diagnosis from each patient also was available for comparison. RESULTS. Forty-eight patients (28 men and 20 women) who ranged in age from 16 years to 86 years were selected and had the following clinical findings: solid or Multiple pancreatic masses diagnosed by computed tomography or magnetic resonance imaging Studies; Simultaneous, suspicious, metastatic masses in the liver, mediastinum, and/or lung; hypoglycemia; multiple endocrine neoplasia type I syndrome; von Hippel-Lindau syndrome; and primary NET of the small bowel. EUS findings revealed solid or multiple masses in the pancreatic head/uncinate, or in the pancreatic body/tail, or simultaneously in the pancreatic head/uncinate and body/tail. Cytologically, 40 patients were diagnosed with NETs (histopathogically confirmed), and 8 patients had findings that were suspicious of NETs (2 patients had false-positive results, and 6 patients had histopathologically confirmed NETs). The most helpful cytologic findings for the diagnosis of NET were a richly cellular sample with a monotonous, poorly cohesive population of small or medium-sized cells with granular chromatin (salt and pepper) and plasmacytoid morphology. Immunocytochemistry confirmed the neuroendocrine origin of tumors in 40 patients (material for immunocytochemistry was inadequate in 8 patients). CONCLUSIONS. The current results indicated that EUS-guided FNA is a useful method for the diagnosis of pancreatic NETs. Cytopathologic examination in coordination with immunocytochemistry can provide an accurate diagnosis in most patients.