Cytology of cystic papillary carcinoma of the thyroid.

Cytologic features in nine cases of cystic papillary carcinoma of the thyroid are described. These cases were from a group of 66 consecutive patients who had papillary carcinomas examined cytologically. The most prominent cytologic findings were clusters and sheets of epithelial cells, enlarged and pale nuclei, intranuclear inclusions and psammoma bodies. Multinucleated giant cells and viscous colloid were not seen in these cystic cases. In eight specimens of resected tissue, the primary lesion was cystic; four cases showed multicentric primary carcinoma, and one showed cystic degeneration in metastases. An evaluation of the cytologic features when cystic degeneration is present may be difficult because papillary cell groups may not be obvious, cell details may be obscured, and intranuclear inclusions and psammoma bodies may be rare or absent.