Aspiration cytodiagnosis of pancreatic endocrine tumours.

We have reviewed fine needle aspirates from 11 patients with pancreatic endocrine tumours and evaluated the diagnostic criteria as well as those proposed in the literature in an attempt to formulate reliable criteria for the cytological diagnosis of these tumours. As expected, no single criterion was reliable for diagnosis: however, cells with rounded or polygonal rather than a columnar shape, cytoplasmic granularity, and eccentricity of round or oval nuclei with a finely stippled, evenly distributed chromatin pattern were features which, taken together, usually enabled one to make a reliable diagnosis. A striking feature of the smears was the cellular monotony and absence of pleomorphism of the tumour cells. Immunocytochemistry and electron microscopy identified tumour products and confirmed the diagnosis.