The Pathological Study On Expression Of VEGF, TGF-β1, CD20, CD45RO And The Detection Of IgH Gene Rearrangement In Hashimoto's Thyroiditis And Primary Thyroid Lymphoma

Objects and methods:Primary thyroid lymphoma and Hashimoto's thyroiditis show morphologic overlaps and may not be clearly distinguished on the basis of light microscopy alone.Thus,it is necessary to explore their transitional relationship and a new method that may help in differential diagnosis.In the first part of our study,we investigated the expression of VEGF,TGF-β1,CD20 and CD45RO in both HT and PTL using immunohistochemical staining in order to explore the role of vascularization and regulation of autoimmune response in the occurrence and development of HT and PTL.The aim in part two was to ascertain the importance of IgH gene rearrangement in distinguishing HT from PTL by semi-nest PCR.All cases from paraffin specimen of 1984～2007 years were selected randomly.Homogeneity of variance test and Student's t test were used to compare the mean age in these cases; One-way ANOVA for the average number of VEGF,TGF-β1 positive thyroid follicle and Chi-square test for positive rate and intensity.Chi-square test(Fisher)was used to compare the IgH gene rearrangement rate.Results:1.The average biopsy rates in 24 years(1984～2007)were:thyroid disease 3.00%,thyroid malignant tumors 2.99%0,PTL 0.10%o.The average proportions of thyroid disease were:thyroid malignant tumors 9.99%,PTL 0.35%.PTL was found in 3.50%thyroid malignant tumors.2.Mean age at onset of 58 cases HT(45.67±10.67)was younger than 13 cases PTL(63.15±9.02)(p＜0.01).61.5%(8/13)PTL was associated with HT.The mean age of HT surrounding PTL(65.38±10.35)was older than HT alone(p＜0.01).But had no statistical difference with that of 5cases HT without PTL(61.78±7.72).The mean age of P-type of HT(52.50±7.08)was older than L-type(40.62±12.04)& O-type(44.79±8.86岁)(p＜0.01),but younger than PTL(p＜0.05).3.The gender of 58 cases HT and 13 cases PTL were apt to female.The sex ratio was 1:19.3 and 1∶12.0,respectively.4.VEGF and TGF-β1 were found to be mainly localized on the cytoplasm of thyroid follicular epithelial cell,lymphocyte and lymphoma cell;CD20 and CD45RO were also mainly expressed in cytoplasm of lymphocyte and lymphoma cell.Most of the lymphoid infiltrate in HT arranged as lymphoid follicles was composed of B cells (CD20+).The interfollicular lymphoid infiltrate was composed predominantly of T cells(CD45RO+).5.Average number of VEGF positive remnant thyroid follicle in PTL(26.69l±13.30 follicles/(×200 HPF))was lower than HT(56.27±28.19)(p＜0.01)as well as HT surrounding PTL(53.15±23.60)(p＜0.05).O-type of HT(68.96±25.97)was higher than bothL-type(49.28±31.43)and P-type(51.02±22.80)(p＜0.05)6.The positive rate of VEGF in thyroid follicle showed an ascending tendency: L-type(50.96%)＜O-type(67.62%)＜P-type(86.37%)＜PTL(99.22%)(p＜0.01). The positive rate in PTL was greater than total HT(64.86%)(p＜0.01)as well as HT surrounding PTL(71.20%)(p＜0.05).7.The positive rate of VEGF in lymphoma cells/lymphocytes of PTL(87.08%) was higher than both total HT(51.64%)and HT surrounding PTL(41.67%)(p＜0.01). P-type of HT(76.67%)was greater than L-type(35.23%)and O-type(46.05%) (p＜0.01).8.Diffuse expression of TGF-β1 positive cells were observed in thyroid follicle of all subtypes HT but without statistical difference.The positive rate of TGF-β1 in lymphoma cells/lymphocytes of PTL(98.33%)was higher than total HT(66.98%) as well as HT(50.00%)surrounding PTL(p＜0.01).9.In subtypes of HT,there was the similar conclusion:the ratio of CD20∶CD45RO was almost 5:4.The expressed difference between CD20 and CD45RO in HT was no significant.Lymphoma cells in PTL were almost expressed CD20 without CD45RO.The expression of CD45RO positive cells were only found in reactive hyperplasia lymphocytes surrounding lymphoma cells.10.IgH gene monoclonal rearrangement rate of PTL(80%)was higher than that of HT(20%)(p＜0.05).Conclusions:1.PTL was found in 0.35%thyroid diseases and 3.50%thyroid malignant tumors from 1984 to 2007 which was lower than average levels in the world.2.Mean age at onset of PTL was older than HT.The gender of them was apt to female.3.The increasing of VEGF in various subtypes of HT and PTL indicated that with the development of disease the angiogenesis and vasopermeability showed an ascending tendency which was involved in exudation,autoimmunological reaction of immunologically competent cells and tumor progression.4.On the basis of HE staining,the positive rate of VEGF in thyroid follicle can be used in auxiliary distinguishing HT from PTL.5.The increasing of TGF-β1 in mesenchyme of PTL compared with HT indicated that TGF-β1 played an important role in the angiogenesis and regulation of autoimmune response.6.Most of the lymphoid infiltrate in HT arranged as lymphoid follicles was composed of B cells(CD20+).The interfollicular lymphoid infiltrate was composed predominantly of T cells(CD45RO+).HT showed a polyclonal hyperplasia. Lymphoma cells Showed monoclonality originated from CD20 positive B lymphocyte. The expression of CD20 and CD45RO were behalf on distinguishing PTL from HT.7.IgH gene monoclonal rearrangement rate of PTL was significantly higher than that of HT.8.L-type of HT were more easy to transform into PTL.9.The detection of IgH gene rearrangement by semi-nest PCR was not sufficient by itself to differential diagnose PTL and L-type of HT,but can be used in distinguishing O-type & P-type from PTL.Therefore it was essential to explore a useful criterion or method for distinguishing PTL from HT.