Objectives: To determine the value of fine-needle aspiration biopsies (FNABs) of the thyroid and stratify the risk of malignancy within the indeterminate FNAB diagnostic category at our institution.
Study design: Case series with chart review of preoperative FNABs of consecutive patients who underwent total thyroidectomy between 2005 and 2007.
Subjects and methods: A total of 115 cases were reviewed, and FNABs were categorized into four groups: benign, positive or suspicious for malignancy, indeterminate (follicular or Hurthle cell lesions), and nondiagnostic. Cytohistologic correlation was then established.
Results: The accuracy of FNAB in detecting thyroid malignancy was 88 percent with false-negative and false-positive rates of 13 percent and 7 percent, respectively. Overall, 52 percent of the indeterminate cases were carcinomas (48 percent of follicular lesions and 62 percent of Hurthle cell lesions). In the presence of cytologic atypia, the rate of malignancy increased to 75 percent and 83 percent for the follicular and Hurthle cell lesions, respectively.
Conclusions: FNAB is an accurate and helpful method for the evaluation of thyroid nodules with results directly correlating with management. Surgery should be considered for FNABs categorized as indeterminate, especially in the presence of cytologic atypia. Because of the high false-negative rate, benign FNABs require close follow-up with ultrasound examination and periodic biopsies.