| 1.BackgroundPapillary thyroid microcarcinoma(PTMC)refers to papillary thyroid carcinoma with a maximum diameter ? 10 mm.In recent years,the prevalence of PTMC has increased sharply due to the widespread use of high-frequency ultrasound and the increasing frequency of people's health checkup.Although most PTMC patients have an excellent prognosis,it should not be neglected that they harbour the risk for extrathyroidal invasions,lymphovascular invasion and lymph node metastasis.It is important to discriminate malignant and benign nodules in patients with a thyroid nodule.Serum thyrotropin(TSH)can promote thyroid follicular epithelial cell proliferation,thyroid hormone synthesis and release,and play an important role in thyroid function and cell proliferation.Recently,many studies have shown that TSH is closely related to differentiated thyroid carcinoma(DTC).Howere,there have been only a few studies concerning the association between TSH and PTMC and the results have been inconsistent.With the development of diagnostic technology and the application of many advanced diagnostic tools,such as three-dimensional ultrasound,MRI,18F-FDG PET/CT genetic test and so on,it provides a new method for the differential diagnosis of thyroid nodules.Because of its good tolerance,low risk,and low cost,ultrasound has become the most commonly used imaging modality for the detection of thyroid nodules.2.ObjectThrough retrospectively analyzing the relationship between serum TSH levels and PTMC and the differences of the ultrasonic examination results in patients with and without PTMC who had undergone thyroidectomy for micronodular thyroid disease,the study attempted to find a simple and effective method for the differential diagnosis of small thyroid nodules and determined the diagnostic validity of thyroid ultrasound in differentiating between benign and malignant small thyroid nodules.3.MethodsA total of 163 eligible patients who accepted thyroid nodule resection in the Second Affiliated Hospital of Zhengzhou University from February 2014 to September 2016 were enrolled,including 113 patients with benign thyroid nodules(benign group)and 50 patients with PTMC(PTMC group).Eligible patients fulfilled the following inclusion criteria:(1)The pathological type of patients with thyroid nodules undergoing initial thyroidectomy is PTC ? 10 mm in diameter or benign tumor;(2)complete medical record materials;(3)Thyroid function tests and ultrasonic examination were done in our hospital.Patients with 1 or more of the following were excluded:(1)PTC > 10 mm in diameter or a final histological diagnosis other than PTC;(2)biochemical and histologic evidence of autoimmunity;(3)history of previous thyroidectomy,radiation exposure,clinical or subclinical hypothyroidism or hyperthyroidism,and familial thyroid carcinoma;(4)history of use of thyroid hormones,anti-thyroid drugs and drugs that can affect thyroid function(eg,estrogen,glucocorticoids).For these patients,the following data were collected: general clinical data,serological results,ultrasonographic results and final histological diagnosis.All analyses were performed using SPSS 17.0 software.4.Results(1)Serum TSH levels in PTMC group were significantly higher than that in benign group(Z =-2.694,P = 0.007),and as TSH increased,the prevalence of PTMC rose clearly(?~2 =8.836,P =0.012).The receiver operating characteristic curve(ROC)analysis showed a TSH cut off point of 1.425 uIU / ml to differentiate benign from malignant thyroid nodules with a sensitivity of 74% and a specificity of 51.6% and with an area under the curve of 0.632 [95% CI : 0.540 ~ 0.725,P = 0.007].The serum TSH levels were positively correlated with tumor size in patients with PTMC(r = 0.298,P = 0.035).In the PTMC group,there was no significant difference in TSH levels between patients with and without lymph node metastasis(Z =-0.579,P = 0.562).(2)The chi square test was used to analyze the number,shape,aspect ratio,echo and microcalcification of thyroid nodules.The results showed that among all ultrasonographic features,there was statistical significance in shape,aspect ratio,echo and microcalcification(all P<0.05)while there was no statistical significance in the number of nodules(P>0.05).Multivariate logistic regression analysis showed that irregular nodular shape,aspect ratio?1,hypoechoic and microcalcification were all valuable for the differential diagnosis of nodules(all P<0.05).Then use these ultrasonographic features as the independent variables of the regression equation of the Logistic regression.Logit(P)=-3.241+1.851×??+1.484×???+1.384×??+2.730×???.The likelihood ratio test was used to evaluate the model.The result was statistically significant(?~2=74.063,P=0.000).Then drew the ROC curve,the area under the curve is 0.873(95%CI:0.809~0.937)5.conclusion(1)Serum TSH is closely related to PTMC and can be used as a predictor of PTMC in small thyroid nodules.(2)Ultrasound is an important method for the differential diagnosis of small thyroid nodules,which can significantly increase the detection rate of PTMC.Irregular nodular shape,aspect ratio ? 1,hypoechoic and microcalcification in a thyroid nodule on ultrasound were very valuable for the differential diagnosis of small nodules. |
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