Previous studies have provided cytologic criteria that aid in the recognition of parathyroid tissue on aspirate smears, including high cellularity, the presence of naked nuclei, loose 2-dimensional clusters, and papillary architecture. However, to the authors knowledge, the cytomorphologic features of parathyroid fine-needle aspiration (FNA) on liquid-based preparations have not been previously described.
The authors retrospectively reviewed all parathyroid FNAs that had aspirate smears and a ThinPrep preparation performed over 10 years at 1 institution. The FNA smears and ThinPrep preparations from each case were deidentified and independently reviewed for cellularity, naked nuclei, architecture, and colloid-like material.
Forty patients were included in the current study. When individual cases were compared, the ThinPrep preparation was more likely to have lower cellularity, lack papillary architecture, lack naked nuclei, and have areas with a microfollicular pattern compared with the FNA smear.
The cytologic features of parathyroid tissue vary depending on preparation. Many of the common features of parathyroid aspirates are lost on ThinPrep preparations, and an increased percentage of parathyroid FNA specimens have a microfollicular pattern on ThinPrep. This may lead to difficulty in recognizing parathyroid origin on FNA.