Fine-needle aspiration cytology of columnar-cell carcinoma of the thyroid: report of two cases with cytohistologic correlation.

The columnar-cell variant of papillary carcinoma is a rare tumor of the thyroid, associated with aggressive behavior, early visceral metastasis, and a rapidly fatal course. In this report we present the fine-needle aspiration cytologic findings of two examples of this variant of papillary carcinoma with cytohistologic correlation. In the smears, clusters, monolayered sheets, and scattered papillary fronds of tumor cells were present. The tumor cells were columnar and exhibited overlapping and stratification of the nuclei. In the first case the tumoral cells showed round nuclei with finely granular chromatin pattern, small nucleoli and vacuolated-appearing cytoplasm. The malignant cells in the second case presented oval to elongated nuclei with stippled chromatin, inconspicuous nucleoli and indistinct cytoplasmic borders. It is important to distinguish this tumor from the common thyroid papillary carcinoma because of its much more aggressive behavior.