Large needle aspiration biopsy histology for preoperative selection of Hürthle cell thyroid nodules

Aims: To assess whether the large needle aspiration biopsy (LNAB) histological distinction between pure microfollicular nodules and mixed micro-macrofollicular nodules can assist preoperative selection of a Hürthle cell nodule (HCN) discovered by fine needle aspiration cytology (FNAC). Methods and results: In 24 HCN identified by preoperative FNAC, preoperative LNAB histology was compared with postoperative pathology. FNAC demonstrated seven benign HCN (negative), eight HCN with atypia (positive); seven suspected cancers with HC (positive); and two cancers with Hürthle cells (positive). LNAB showed mixed micro-macrofollicular hyperplastic features in 12 nodules (negative) and a microfollicular structure in 12 nodules (positive), two of which included findings of papillary cancer. Postoperative findings were benign (negative) in 16 patients and malignant (positive) in eight patients. The sensitivity and specificity for FNAC were 87.5% [seven of eight, 95% confidence interval (CI): 47.3-99.7%) and 37.5% (six of 16, 95% CI: 15.2-64.6%], respectively, and for LNAB were 87.5% (seven of eight, 95% CI: 47.3-99.7%) and 68.8% (11 of 16, 95% CI: 41.3-89.0%), respectively. FNAC results were significantly different from postoperative results (McNemar's test, exact two-sided P=0.012), while LNAB results were not (McNemar's test, exact two-sided P=0.219). Conclusions: These data suggest that LNAB histology is more accurate than FNAC cytology for the preoperative selection of HCN.