A 3-year audit of thyroid fine needle aspirates

Fine needle aspiration (FNA) cytology is an important adjunct to the preoperative management of thyroid swellings. It is a simple and highly cost effective procedure with a higher sensitivity for the detection of malignancy than ultrasound and radio-isotope scans. We audited a total of 208 aspirates performed over a 3-year period. In our experience 61% of solitary thyroid swellings can be diagnosed confidently on FNA cytology as either non-neoplastic (46%) or neoplastic (15%). Based on these two groups the sensitivity is 91% and specificity 94%. The specificity, however, decreases to 40% if the group reactive vs neoplastic, which comprises 10-15% of cases and requires surgical intervention, is included. The positive predictive value for malignant disease is 94% while the false-negative and -positive rates excluding the unsatisfactory and reactive vs neoplastic groups are low at 2.7% and 5.4%, respectively (involving non-neoplastic lesions and benign tumours only). There was no case of malignant cytology with a benign biopsy follow up.