Consequences of the COVID-19 pandemic on the structure of surgical pathology of the thyroid gland

Changes in the incidence of thyroid pathology during the COVID-19 pandemic were noted by many authors; multicenter global studies are also devoted to this problem, showing not only a general increase in the incidence rate, but also some negative consequences due to delayed surgical interventions [1]. The increase in the incidence of the surgical pathology is apparently associated with antigenic mimicry of the virus to the components of the colloid and cells of the thyroid parenchyma and, accordingly, with cross-reactivity when its tissue is damaged by cytokines and immune complexes in the acute and subacute periods of the disease [2, 3]. In general, the impact of the pandemic on thyroid pathology is of interest both from the point of view of practical medicine and from the standpoint of fundamental research.

The aim of the study is to investigate the consequences of the COVID-19 pandemic on the structure of surgical pathology of the thyroid gland and the characteristics of papillary carcinomas.

MATERIALS AND METHODS

The structure of thyroid pathology was studied in patients of specialized endocrine surgery centers of the Republic of Crimea and Sevastopol based on cytological and histological findings of morphological diagnostics at the preoperative and postoperative stages. The study was conducted in a comparative aspect in the period up to 2020 before the pandemic, in the period 2020-2021 at the culmination of the pandemic, in 2022 as early consequences of the infection caused by Sars-CoV-2 with respect of the thyroid gland, as well as in the period 2023 and early 2024 as intermediate and late consequences in the period after the pandemic termination. The research work complies with the ethical principles of the Declaration of Helsinki by the World Medical Association (WMAD Helsinki, 1964, ed. 2013). The study was ap- proved by the local committee of the Vernadsky Crimean Federal University on biomedical ethics (extract from the minutes of the meeting No. 7 dated 06/23/23).

RESULTS

While working in the endocrine surgery clinic, we noticed a change in the structure of surgical morbidity during the peak of Sars-CoV-2 virus cases, as well as in the early and late periods after the COVID-19 pandemic. We noted an increase in the incidence of surgical pathology among the male population, the prevalence of autoimmune processes accompanied by thyrotoxicosis and the formation of toxic adenomas in the early period and at the culmination of the pandemic. In case of long-term consequences, we identified a change in the structure of tumor pathology: a greater rate of detection of papillary adenocarcinoma of the thyroid gland. Thus, during the pandemic, the incidence of toxic goiter significantly increased from 10.8% to 26.6% (at p≤0.05), followed by a decrease to 12.3%, 11.6% and 16.3% in 2022-2024, respectively.

The incidence of the tumor pathology changed not during the peak, but in the early and intermediate post-pandemic period. The incidence of papillary cancer (the most common form of thyroid cancer) increased by 1.5-2 times after the pandemic. In the pre-pandemic period, it was 22.6% of all surgical pathology, during the pandemic it reached 21.4%, and in the early period after the peak of the pandemic (2022) the indicator was 32.9% (at p≤0.05); in the intermediate (2023) it was accounted for 45.4% (at p≤0.05), decreasing only in the first half of 2024 to 24%. The same trend was noted for B-cell adenomas. Before the pandemic, they accounted for 5.4% of the overall structure of surgical pathology, during the pandemic they amounted to 2.4%, and after the peak their number increased sharply, amounting to 8.2% (at p≤0.05) with a subsequent decrease to 3.4-4.8% in 2023-2024. In the general population of the Crimean patients, we did not note reliable differences for different variants of papillary cancer (metastatic forms, follicular and B-cell variants, tall-cell variant), as well as for medullary cancer.

It is interesting that the incidence of autoimmune thyroiditis requiring surgical treatment in the overall structure of surgical pathology of operated patients has decreased, despite the known fact of sensitization of the glandular tissue due to the cross-reactivity of its components with the antigens of the Sars-CoV-2 virus. Thus, before the pandemic in 2019, surgical operations for AIT 36 | Cardiometry | Issue 33. November 2024

were performed in 5.4% of the patients, during the pandemic (2020-2021) in 7.1%, in the early period after the peak (2022) - 5.5%, but in the late period (2023-2024) already in 2.3% and 1.9% of the cases, respectively. During the same periods, a gradual, but steady, increase in the incidence of follicular adenomas was noted: from 17.2% before the pandemic to 27.9% in 2024.

Thus, it can be assumed that the Sars-CoV-2 virus, due to cross-reactivity [2, 3], affects the occurrence of toxic forms of goiter and toxic adenomas in the acute period of the disease only and does not elevate the percentage of chronic autoimmune thyroiditis in the later period. At the same time, the pandemic has a significant impact on the incidence of tumor pathology not only due to the limitation of timely surgical care, but also due to the effect of the virus on thyroid cells, apparently contributing to their onco-transformation through stress mechanisms or other pathogenetic methods that requires further study [1, 4].

CONCLUSION

The COVID-19 pandemic has had a significant impact on the structure of general surgical and on-copathology of the thyroid gland that should require alertness and a comprehensive assessment of risk factors when treating patients.

The research work was supported by State Task Ref. FZEG-2023-0009 “Study of the heterogeneity of the tumor microenvironment as a factor in its aggressiveness and resistance to therapy”, No. 123030700011-4 dated 03/07/2023.