Endocrine Abstracts

Background: Thyroid fine-needle aspiration (FNA) is a safe, valuable and cost effective procedure and is now regarded as the investigation of choice for preoperative assessment of thyroid nodules. The reported sensitivity of thyroid FNA varies from 65 to 98% and the specificity from 73 to 98%.

Aim: The aim of this study was to assess the accuracy of this procedure correlating cytology with histological outcomes, and to audit our practice against standard recommendations and published literature.

Methods: The cytological diagnoses of all thyroid FNA biopsies performed during the 5 years period (2008–2012) were retrieved retrospectively from the Pathology Laboratory Information System.

Results: 567 thyroid FNAs were performed on 433 patients. The cytological diagnoses were as follows: Thy1 (non-diagnostic) in 63 (11.1%) cases, Thy2 (benign) in 424 (74.8%) cases, Thy3 (follicular lesion) in 54 (9.5%) cases, Thy4 (suspicious for malignancy) in nine (1.6%), and Thy5 (malignant) in 17 (3%) cases. Of 63 cases which were non-diagnostic, 25 had a repeat sampling, and of those a diagnostic aspirate was achieved in 84% (n=21) of cases. 80% of FNAs were performed under US guidance with onsite cytopathology evaluation, and the inadequacy rate was significantly lower in the US guided FNA compared to the free-hand aspirates (8.7% vs 15.7%, respectively, P<0.05). 111 patients had either partial or total thyroidectomy, of which 69 (62.2%) were benign and 43 (37.8%) were malignant nodules. The sensitivity and specificity for detecting neoplasia were 87.5 and 83% respectively.

Conclusions: Thyroid FNA is a reliable and accurate procedure in triaging patients with thyroid nodule for surgery. Our findings are consistent with the standard recommendations and published literature. The use of US guided FNA coupled with onsite evaluation by pathologist should be the standard practice in all cases of thyroid nodules referred for FNA in order to reduce inadequacy rate and improve accuracy.