The accuracy of fine needle aspiration cytology in the tryroid nodule study, in a tertiary hospital
Beatriz Torres Torres1, Gonzalo Maldonado Castro1, Luis Irigoyen Cucalón1, Blanca Catón Santaren2, Julia De Diego2 & Rafael Ezquerra Larreina1
Background: Fine Needle Aspiration (FNA) is currently the primary diagnostic procedure in diagnosing thyroid malignancy. The aim of this study was to report our experience with FNA, and its accuracy.
Materials and methods: Retrospective analysis of 166 patients who were operated of thyroid nodule in our hospital from 2003 to 2008, all of them had a previous FNA cytology results. There were evaluated some clinical variables and the correlation with final histopathologic diagnosis, we also studied the specificity, sensitivity, positive predictive value, negative predictive value of the FNA.
Results: A total of 212 thyroid FNA were obtained from 166 patients; 88.5% were women, 28.8% were solitary nodules, the average nodule size was 28.8 mm (1072), of which 48.2% on the right side. After the first FNA 72 (42%) were negative for malignacy, 55 (33%) were suspicious for malignancy, 12 (7.2%) malignant and 27 (16.2%) unsatisfactory. The FNA was repeated in 36 patients (27 for unsatisfactory previous cytology and 9 for thyroid nodule change during the follow-up) being the results: 18 (50%) were benign, 10 (27.7%) were suspicious for malignancy, 1 (3.3%) malignant and 7 (19%) unsatisfactory. Ten patients did a third FNA being 1 malignant, 7 negative for malignancy and 2 unsatisfactory. Sixty-six (40%)patients were operated for other causes than FNA cytology results, such the size of nodule or compressive goiter. The histologic results were: 33 (20%) follicular adenoma, 100 (60%) nodular goiter, coloide nodule or lymphocytic thyroiditis and 33 (20%) carcinomas 21 (63.6%) papillary carcinoma, 11 (33.3%) follicular carcinoma, 1 (3%) medullar carcinoma. In the carcinoma group after two FNA 2 patients had a benign cytology, both were described as micropapillary carcinoma. The specificity, sensitivity, positive predictive value, negative predictive value of the FNA cytology were 91.5, 92.3, 90, 93% respectively. Sixty percent were palpation-guide FNA and 40% were US-guide FNA. Comparing the accuracy between both (palpation guide vs US-guide): the unsatisfactory FNA was 20 vs 12.5% and the specificity, sensitivity of the FNA cytology were respectively: 88 vs 94.7%; 75 vs 100%.
Conclusions: The accuracy of FNA improves with US-guide FNA although if the indication of palpation-guide FNA is well-done the accuracy would be similar, however FNA cytology is an excellent diagnostic test in the thyroid nodule study.