The goal of this study was to evaluate the diagnostic accuracy of preoperative fine needle aspiration biopsy cytology (FNAB-C) in predicting lateral lymph node metastasis in papillary thyroid cancer patients.

A total of 592 patients who underwent thyroid cancer surgery and intra-operative lateral cervical LN frozen section or RND, from January 2002 to December 2011, were evaluated retrospectively. Among them, 228 cases had suspicious findings in FNAB-C of lateral nodes. We reviewed their radiological and pathological reports.

Intra-operative frozen section examination was performed in 540 cases and RND was performed in 314 cases. This study included 534 women (83.4%) and 106 men (16.6%). Patients' ranged in age from 9 to 83 years (mean, 45.65 years). FNAB-C was performed in 228 cases. The sensitivity and specificity of FNAB-C was 71.5% and 78.6%, respectively; 35.9% of cases had a false negative result. The combination of FNAB-C and intra-operative frozen section test sensitivity and specificity was 87.2% and 93.6%, respectively.

The results for sensitivity in FNAB-C actually appear low, and false negative results were very high. In papillary thyroid cancer in patients with FNAB-C, even if the result is negative, if lymph node metastasis is suspected based on radiologic evidence, frozen section examination should be performed for determination of metastasis.