Effect of nodule size on the reliability of fine-needle aspiration biopsy in thyroid nodules

Turkish Journal of Medical Sciences Turk J Med Sci (2014) 44: 1002-1009 © TÜBİTAK doi:10.3906/sag-1312-56 http://journals.tubitak.gov.tr/medical/ Research Article Effect of nodule size on the reliability of fine-needle aspiration biopsy in thyroid nodules 1 2 1 3, Ali Erkan UÇAR , Seyit Muhsin SARIKAYA , Ömer PARLAK , Abdussamed YALÇIN * Department of General Surgery, Ankara Atatürk Education and Research Hospital, Ankara, Turkey 2 Department of General Surgery, Kayseri Education and Research Hospital, Kayseri, Turkey 3 Department of General Surgery, Faculty of Medicine, Yıldırım Beyazıt University, Ankara, Turkey 1 Received: 10.12.2013 Accepted: 17.02.2014 Published Online: 24.10.2014 Printed: 21.11.2014 Background/aim: To investigate the reliability of fine-needle aspiration biopsy (FNAB) in thyroid nodules and benign/malignant discrimination, particularly in large nodules. Materials and methods: A retrospective analysis of 1466 nodules in 402 patients with thyroid nodules who underwent thyroid surgery was made. The pathologic results of the thyroid nodules from preoperative FNAB and postoperative surgical pathology results were compared. Results: FNAB was found to be in accordance with the postoperative pathologic results. A concordance between the FNAB and postoperative pathologic results, particularly in nodules less than 3 cm in size, was detected. However, a similar finding was not detected in nodules larger than 3 cm in size. The rates, calculated without taking into consideration the nodule dimensions, were found to be: sensitivity, 47.65%; specificity, 93.98%; false-negative, 52.35%; and false-positive 6.02% Conclusion: In our experience, the false-negative rate of FNAB in nodules larger than 3 cm was high. Therefore, we have concluded that in the event of malignant FNAB, this rate is significant; however, in the event of benign FNAB, it should not be trusted too much. Key words: Thyroid nodules, thyroid cancer, surgery 1. Introduction Thyroid nodules are commonly detected in the general population, with an incidence of 17% to 67% found in adults during ultrasonography. The incidence of thyroid cancer is generally low. It was shown that thyroid carcinoma frequency is higher in large thyroid nodes. Fine-needle aspiration biopsy (FNAB) is the gold standard initial step for the evaluation of thyroid nodules and has significantly reduced the number of surgeries performed unnecessarily for diagnostic purposes (1,2). Unfortunately, FNAB cytology seems to have a high false-negative rate in large nodules. 2. Materials and methods In this study, the FNAB pathology results and the postoperative pathology results of patients who underwent thyroidectomy due to a nodular goiter were compared and, additionally, we investigated whether the dimension of the thyroid nodule had an impact on the FNAB results. This study was performed retrospectively by evaluating the records of patients who underwent thyroidectomy due to nodular goiter in the Second Department of General * Correspondence: 1002 Surgery of the Ankara Training and Research Hospital of the Ministry of Health between July 2006 and August 2008. Overall, 487 patients who underwent thyroidectomy with the diagnosis of nodular goiter were evaluated. Of those, 402 patients whose age, sex, symptoms, physical examination findings, and ultrasonography, free triiodothyronine (T3), free thyroxine (T4), total T3, total T4, and thyroid-stimulating hormone (TSH) results were available and who had had a FNAB procedure were included. Eighty-five patients with cystic nodules, who had previously had a thyroidectomy and a relapsed thyroidectomy, were excluded from the study. Serum T3, T4, and TSH levels were checked in all patients included in the study, and all patients underwent thyroid ultrasonography and ultrasound-guided FNAB. Nodule dimensions, number of nodules, FNAB pathology results, and postoperative pathology outcomes were recorded according to the results of thyroid ultrasonography. All euthyroid patients and those with hypothyroidism who were included in the study underwent ultrasoundguided FNAB. Patients who had toxic and/or had laboratorial hyperthyroidism underwent the same UÇAR et al. / Turk J Med Sci procedure after becoming euthyroid following medical antithyroid treatment. The results of the FNAB pathology were divided into 4 groups as malignant, benign, suspicious, and insufficient material in terms of malignancy. The FNAB procedure was repeated in patients whose pathology results were found to be insufficient. The pathology reports in which malignancy was suspected and those that were reported as insufficient material again after the third repeat were included in the malignant group. The results of these 4 groups were collected into 2 groups as benign and malignant to be used in statistical analysis in this study. Hurthle cell carcinoma, medullar carcinoma, follicular carcinoma, papillary carcinoma, and undifferentiated thyroid carcinoma were considered as malignant thyroid diseases. Remaining diseases, reported as Hurthle cell adenomas, diffuse hyperplasia, follicular adenoma, granulomatous thyroiditis, Hashimoto’s thyroiditis, lymphocytic thyroiditis, nodular hyperplasia, nodular colloidal goiter, and Riedel thyroiditis, were grouped as benign. Statistical analysis in this study was performed based on the data collected, including FNAB pathology results, postoperative pathology outcomes, and nodule dimensions. 2.1. Statistical analysis The SPSS (SPSS Inc., Chicago, IL, USA), was used in the statistical analysis. In addition to the descriptive statistical methods (mean, standard deviation), Student’s t-test was used for comparison of the descriptive data with normal distribution when the study data were evaluated. For comparison of the qualitative data, chi-square, McNemar, and kappa goodness-of-fit tests were used. Results were evaluated at the 95% confidence interval and the P < 0.05 significance level. 3. Results A total of 1466 nodules were identified in patients by ultrasonography. Of the patients, 313 (77.86%) were female and 89 (22.14%) were male. Mean patient age was 47.67 ± 12.82 years (range: 17–79). Median patient age was 47 years. The women’s ages ranged between 17 and 79, with a mean age of 46.96 ± 12.89 and a median of 46. The men’s ages ranged between 19 and 75; their mean age was 50.18 ± 13.30 and the median was 50. The female-to-male ratio was found to be 3.52:1. In terms of the distribution of nodules by sex, the number of nodules was 1139 (77.70%) in female patients and 327 (22.30%) in male patients (Table 1). Regarding nodule dimensions measured according to ultrasonography, the smallest nodule was measured as 2 mm in size and the largest nodule size was 100 mm. When we classified nodules according to their sizes as 0 to 9 mm, 10 to 19 mm, 20 to 29 mm, 30 to 39 mm, and larger than 40 mm, the majority of the nodules (39.56%) were found to be in the small nodule group of 0 (...truncated)