Dynamic histopathological changes of thyroid nodule after microwave ablation and its clinical significance / 第二军医大学学报

ABSTRACT

Objective: To investigate the changes of tissue structure in the ablation area after microwave ablation of thyroid nodules and to identify the appropriate time for pathological evaluation of the ablation area. Methods: From January 2017 to December 2018, a total of 69 core-needle biopsy tissue samples from the ablation area of thyroid nodules in 60 patients were investigated histologically using H-E and immunohistochemical staining. The samples were taken after microwave ablation at different stages and from different areas. Cellular morphology and tissue structure as well as thyroid transcription factor 1 (TTF1) in the tissues from the central zone and marginal zone of ablation area were observed immediately, 1 month, 3 months, 6 months and 12 months after microwave ablation. Results: Successful biopsies were achieved in 69, 12, 19, 25 and 13 ablation areas immediately, 1 month, 3 months, 6 months and 12 months after microwave ablation. There was no necrosis but only coagulated degeneration in both the central zone and marginal zone of the 69 (100.00%) ablation areas immediately after microwave ablation. At 1 month after microwave ablation, 9 (75.00%) samples of central zone and 9 (75.00%) samples of marginal zone showed complete necrosis. At 3 months, 16 (84.21%) samples of central zone and 15 (78.95%) samples of marginal zone showed complete necrosis. At 6 and 12 months, all (100.00%) samples of central zone and marginal zone became necrotic completely. Conclusion: The histopathologic feature of thyroid nodules after microwave ablation varies with time. There is only coagulated degeneration in the freshly ablated thyroid tissue, and no necrosis is found. Necrosis occurs and progresses to the whole ablation area in all patients. It suggests that the reliable therapeutic effect of microwave ablation on thyroid nodules is due to complete necrocytosis. Necrosis occurs in all the ablation area at 6 months after microwave ablation, indicating the 6th month is an appropriate time for pathological evaluation of the ablation area.