The Analysis Of Histopathological Characters Of IgG4 Positive Hashimoto's Thyroiditis

Objective:To investigate the histological features of IgG4 positive Hashimoto's thyroiditis by researching the expression of IgG4 in tissues of thyroid diseases,so that to improve the understanding of IgG4 positive Hashimoto's thyroiditis and provide a basis for diagnosis and differential diagnosis.Methods:Immunohistochemistry was carried out for assessment of the expression of IgG4 in 66 Hashimoto's thyroiditis patients(group ?),16 Hashimoto's thyroiditis with adenoma patients(group ?),and 40 Hashimoto's thyroiditis with micropapillary carcinoma patients(group ?).Statistical analyses of the difference in the proportion of IgG4 positive cases among groups.Based on the immunohistochemical results,Hashimoto's thyroiditis patients were divided into IgG4 positive group and IgG4 negative group.Statistical analyses of stromal fibrosis,lymphocytes/plasma cells infiltration,thyroid follicular size,and follicular epithelial degeneration were also conducted in both groups.Univariate and multivariate analysis were used to screen the histopathological risk factors of IgG4 positive thyroid diseases.The differences of the above-mentioned risk factors between IgG4 positive cases in group ? and group ? were compared,as well as group ? and group ?.Results:21 of 66 Hashimoto's thyroiditis cases(31.82%)were diagnosed as IgG4 positive cases and 45 were IgG4 negative cases;4 of 16 Hashimoto's thyroiditis with adenoma cases(25.00%)were diagnosed as IgG4 positive cases and 12 were IgG4 negative cases;8 of 40 Hashimoto's thyroiditis with micropapillary carcinoma cases(20.00%)were diagnosed as IgG4 positive cases and 32 were IgG4 negative cases.Although the proportion of IgG4 positive cases in group ? was higher than that in group ?,there was no significant difference(?2=0.052,P=0.819).Similarly,group ? was higher than that in group ? but there was no significant difference(?2=1.750,P=0.186),and group ? was higher than that in group ? but no significant difference(?2=0.003,P=0.959).Compared with IgG4 negative Hashimoto's thyroiditis,IgG4 positive Hashimoto's thyroiditis showed more moderate and severe stromal fibrosis(?2=24.147,P<0.001)and lymphocytes/plasma cells infiltration(?2=35.058,P<0.001).There was no significant difference in follicular size(?2=5.146?=0.069)and follicular epithelium denaturation(?2=5.312,P=0.087)between the two groups.Multivariate Logistic regression analysis showed that stromal fibrosis and lymphocytes/plasma cells infiltration were the main histopathological risk factors of IgG4 positive Hashimoto's thyroiditis(P<0.05).Statistical analysis showed that there was a significant statistical relationship in stromal fibrosis model between IgG4 positive Hashimoto's thyroiditis and IgG4 negative Hashimoto's thyroiditis(P<0.05).In 21 IgG4 positive Hashimoto's thyroiditis,the IgG4 positive plasma cells distribution of 18 cases was thyroid follicular space and the other 3 cases were also distributed in lymphoid follicles.There was no difference in stromal fibrosis model and the distribution of IgG4 positive plasmacytes between the IgG4 positive cases in group ? and group ? and those with positive IgG4 in group ?.Conclusion:IgG4 positive Hashimoto's thyroiditis is common.There was no significant difference in the proportion of IgG4 positive cases among Hashimoto's thyroiditis,Hashimoto's thyroiditis with adenoma or micropapillary carcinoma.The major histopathological risk factors for IgG4 positive Hashimoto's thyroiditis were stromal fibrosis and lymphocytes/plasma cells infiltration.Interfollicular fibrosis is the most common fibrosis pattern in IgG4 positive group and interlobular fibrosis is the most common fibrosis pattern in IgG4 negative group.IgG4 positive cells are mainly distributed in thyroid follicular space in IgG4 positive Hashimoto's thyroiditis,which may be accompanied by lymphatic follicular distribution.Whether the pattern of stromal fibrosis and IgG4 positive plasmacyte distribution is related to thyroid adenoma or micropapillary carcinoma is still uncertain.