Fine needle aspiration of parathyroid lesions

OBJECTIVE: To assess the cytologic features of parathyroid lesions and to determine if it is possible to differentiate between parathyroid hyperplasia (PH) and parathyroid adenoma (PA) based on fine needle aspiration (FNA). STUDY DESIGN: FNAs of 14 parathyroid lesions were performed during intraoperative consultation. Alcohol-fixed, Papanicolaou-stained smears and air-dried Diff-Quik-stained smears were prepared in each case. Cytologic features were evaluated. RESULTS: All cases, PA and PH, showed numerous bare nuclei in the background. Ninety percent of PA contained microfollicular groups in addition to sheets and syncytia, while PH was arranged primarily in sheets and syncytia without microfollicles. Nuclear pleomorphism was seen in 33% of PA and absent from PH. CONCLUSION: Careful evaluation of cytologic features might help to differentiate between PA and PH on FNA.