| Background: The fine needle aspiration cytology, has become one of the the most effective examinations internationally recognized in diagnostics of thyroid nodules. With FNAC technology continues to mature and develop, thyroid cancer detection rate has also been improved. But there is still a large part of nodules which FNAC results suggest benign, however, postoperative pathology findings suggest malignancy,the false negative cases. How to reduce the false negative rate,and on what basis is more suitable to guiding of thyroid carcinoma, the international experts and scholars always have different opinions. So it is very necessary to observe the false negative results of fine needle aspiration cytology and evaluate its value of diagnostic for thyroid cancer.Objective: The aim of stuudy is to review the independent risk factors of fine needle aspiration cytology false-negative results and assess the value of fine needle aspiration cytology in the diagnosis of thyroid cancer.Methods: A retrospective analysis from October 2014 to October 2015 period, 612 cases of patients all have the FNAC results which puncture by the same sonographer and the same cytology examining physician, and all treated at the Department of Thyroid Surgery, the First Hospital of the Jilin University,Changchun,China.All patients have been prepared for Ultrasound examination, laboratory tests and other routine examinations preoperative and have the results of FNAC,intraoperative frozen section examination and postoperative pathology.Comparing 27 false-negative patients to 36 true-negative patients in two groups analyzing the factors of nodule size(≤0.5cm or >0.5cm), multiple centers,cancer with Hashimoto’s thyroiditis, cancer with hyperthyroidism, ultrasound remindes calcification, TSH, FT3, FT4 and heart rate and separately compared the sensitivity,specificity, accuracy, negative predictive value, positive predictive value, false negative rate and false positive rate of all the nodules and malignant nodules in both group FNAC and group intraoperative frozen section.Results: Nodules≤0.5cm, multiple centers, cancer with Hashimoto’s thyroiditis and ultrasound remindes calcification,P<0.05,are easily lead to the false negative results with statistically significant. Nodules>0.5cm,cancer with hyperthyroidism,the value of TSH, FT3, FT4 preoperative and heart rate, P>0.05, there is no significantly difference. The incidence ratio of thyroid cancer of male and female is 1: 3.2, the patient whose age of onset is between 41 to 50 years old has the highest incidence, and whose age of onset is ≥71 or ≤20 years old has lowest incidence.The overall sensitivity, specificity, accuracy, negative predictive value, positive predictive value, false negative rate and false positive rate of FNAC VS intraoperative frozen section are 95.24%, 90.16%, 94.12%, 98.36%, 57.14%, 9.84%, 4.76% VS 98.41%, 93.33%, 98.04%, 99.47%, 82.35 %, 6.67%, 1.56%. For the diagnosis of malignant nodules, the accuracy of group FNAC and group intraoperative frozen section is 98.37% and 97.83%, respectively and the misdiagnosis rate is 1.63% and 2.17% respectively, the accuracy of FNAC is a little higher than intraoperative frozen sections, we have already could diagnosis of thyroid cancer depend on the class V or class VI result of FNAC.Conclusion: 1.Nodules≤0.5cm,multiple centers,cancer with Hashimoto’s thyroiditis and ultrasound remindes calcification are easily lead to the false negative results.2.Nodules>0.5cm and cancer with hyperthyroidism aren’t the independent risk factors of false negative results.The false negative result is irrelevant to the value of TSH, FT3, FT4 preoperative and heart rate.3. From a qualitative point of view, we can diagnosis of thyroid cancer depend on the class V or class VI result of FNAC, but for the surgery which needs to be known about capsule invasion, lymph node metastasis and multiple lesions and so on,the intraopretaive frozen section examination is still needed. |
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