ABSTRACT
Fine needle aspiration biopsy of the thyroid (FNAB) has become an accepted procedure for evaluation of the thyroid nodule, with 899 performed at the Lahey Clinic from 1981 to 1990. We examined them by medical record, pathology and cytology review, with follow up by chart or personal communication. Three hundred forty five came to surgery, of which 188 (34 percent) were malignant; the specificity of the aspirate was 97 percent, sensitivity 92 percent, with false negative of 8 percnt and false positive rate of 5 percent. In combination with frozen section, the fine needle aspirate result improved the accuracy of the intraoperative estimate of malignancy (p=0.03). When the aspiration was benign but the lesion was clinically suspicious, a cancer was found at surgery in 13 percent of cases. Of the patients observed for a minimum of 5 years, 1,3 percent developed a carcinoma. Both cases had a non diagnostic FNAB. None of the patients with a clinical and cytological benign lesion developed cancer. The complication rate of FNAB was 1.3 percent. FNAB is a helpful and low risk diagnostic procedure but it needs to be done and read appropriately and its result used within the clinical context. Each medical team needs to monitor their results (continued quality control)