Fine-needle aspiration cytology in pancreatic endocrine tumors.

Pancreatic endocrine tumors (PETs) are relatively uncommon neoplasms. Although their histologic patterns have been widely studied, their cytologic features as they appear in fine-needle aspiration (FNA) specimens have rarely been reported. In this study, aspirates of seven PETs, four primary and three metastatic lesions (two to liver and one to bone), are described. The tumors occurred in seven men ranging in age from 37 to 72 yr. Six tumors presented as nonfunctioning masses and one produced Zollinger-Ellison syndrome. Three were located in the head of the pancreas and four in the body and tail. The pancreatic and liver aspirations were performed under computed tomographic guidance and the bone lesion, under fluoroscopy. The aspiration specimens were hypercellular. The tumor cells occurred singly and in small clusters. In three cases, there was a tendency toward acinar formations. In two cases, there were prominent, thin-walled, branching blood vessels with tumor cells attached to the vascular walls. The cells were round or polygonal with a moderate amount of finely granular, well-defined cytoplasm. The nuclei were eccentrically located and round-to-oval--with one or two small nucleoli and finely granular, evenly-dispersed chromatin. The diagnosis was confirmed by immunocytochemistry (two cases) and electron microscopy (four cases) of the aspirated material and histology sections of the resected tumors (two cases). The results of this study demonstrate that FNA is a useful method to establish the diagnosis of PETs.