PANCREATIC ONCOCYTIC ENDOCRINE TUMORS - CYTOLOGIC FEATURES OF 2 CASES

BACKGROUND: Oncocytoma designates a usually benign tumor consisting of oncocytes (cells rich in mitochondria). Rarely do endocrine pancreati c tumors show oncocytic transformation, and consequently their liver m etastases may resemble a hepatocellular carcinoma. CASES: Case 1, a 36 -year-old male, presented with an 8-cm pancreatic mass with multiple l iver metastases. Fine needle aspiration (FNA) biopsy was performed on the liver. The cytologic features were highly cellular material; numer ous isolated cells and irregular, loose cellular aggregates; rare mito ses; round or polygonal cell shape; rosette formation; and large, gran ular, eosinophilic cytoplasm (suggestive of poorly differentiated hepa tocellular carcinoma). Case 2, a 57-yenr-ald female with hypoglycemia, had a 13-cm pancreatic mass. FNA material showed the same cytologic f eatures as case 1. In situ hybridization to detect albumin mRNA was ne gative in both cases, while immunocytologic reactions for glandular ep ithelial cytokeratin and chromogranin A were positive. Case 2 was also positive for insulin. CONCLUSION: Oncocytic transformation in endocri ne tumors of the pancreas is a rare occurrence and must be kept in min d in the diagnostic workup of FNA material from turners of the hepatop ancreatic region.