Fine-needle aspiration biopsy of papillary thyroid carcinoma: cytologic, histologic, and ultrastructural correlations

Aspiration smears from a series of 21 papillary thyroid carcinomas were studied and a number of morphologic features correlated with the histologic and ultrastructural patterns. These included types of papillary structures, metaplastic cells, grooved and lobulated nuclei, optically clear nuclei, intranuclear inclusions, and macrophages. Generally there was a close correlation between histologic and cytologic findings. The numbers of macrophages and metaplastic cells appeared to be exaggerated in aspiration smears as compared with those seen on histologic sections. Optically clear nuclei were not seen on the air-dried cytologic smears. Grooved nuclei were somewhat difficult to recognize in the aspiration smears, although lobulated nuclei were identified easily. We consider the latter to be a significant feature in the diagnosis of papillary carcinoma. Ultrastructurally grooved nuclei showed a deep linear indentation of the nuclear membranes. Lobulated nuclei were characterized by multiple indentations that divided the nucleus into several lobules.