Detection of SARS-CoV-2 infection in thyroid follicular cells from a COVID-19 autopsy series

Thyroid dysfunction in COVID-19

The COVID-19 pandemic has affected over 772 million people globally. While lung damage is the major contributor to the morbidity and mortality of this disease, the involvement of multiple organs, including the endocrine glands, has been reported. This Review aims to provide an updated summary of evidence regarding COVID-19 and thyroid dysfunction, incorporating highlights of recent advances in the field, particularly in relation to long COVID and COVID-19 vaccination. Since subacute thyroiditis following COVID-19 was first reported in May 2020, thyroid dysfunction associated with COVID-19 has been increasingly recognized, secondary to direct and indirect effects on the hypothalamic-pituitary-thyroid axis. Here, we summarize the epidemiological evidence, pattern and clinical course of thyroid dysfunction following COVID-19 and examine radiological, molecular and histological evidence of thyroid involvement in SARS-CoV-2 infection. Beyond acute SARS-CoV-2 infection, it is also timely to examine the course and implication of thyroid dysfunction in the context of long COVID owing to the large population of survivors of COVID-19 worldwide. This Review also analyses the latest evidence on the relationship between the therapeutics and vaccination for COVID-19 and thyroid dysfunction. To conclude, evidence-based practice recommendations for thyroid function testing during and following COVID-19 and concerning COVID-19 vaccination are proposed.

Examining the impact of several factors including COVID-19 on thyroid fine-needle aspiration biopsy

OBJECTIVE

The study explores various factors, including coronavirus disease 2019 (COVID-19) history and vaccination status, that influence the classification value of ultrasonography-guided thyroid fine needle aspiration biopsy (TFNAB) by comparing non-diagnostic (Bethesda-I) and diagnostic (Bethesda II-VI) results.

METHODS

We conducted a retrospective observational study in a high-volume tertiary care center involving patients who underwent TFNAB from November 2022 to April 2023. The study retrospectively analyzed the cytopathology of 482 thyroid nodules. Patients were categorized into non-diagnostic (n = 136) and Diagnostic groups (n = 346) based on TFNAB. A comprehensive set of parameters was examined, including demographic, anthropometric and clinical data, thyroid ultrasonography findings, COVID-19 history and immunization status.

RESULTS

The mean age was 55.1 ± 12.1 years in the non-diagnostic group and 53.5 ± 13 years in the Diagnostic group (p = .223). 75.7% (n = 103) of the non-Diagnostic group and 82.9% (n = 287) of the Diagnostic group were male (p = .070). The mean nodule longitudinal diameter of the Diagnostic group was significantly higher than that of the non-diagnostic group (p = .015). The TIRADS score of the nodules showed a statistical difference between the groups (p = .048). The groups had no significant differences regarding other ultrasonographic parameters and COVID-19-related variables.

CONCLUSION

It can be assumed that when the longitudinal diameter of the thyroid nodule is small and in TIRADS categories other than the TIRADS3 category, TFNAB is less likely to be diagnostic. However, future research may be needed to confirm these findings and uncover any long-term effects of COVID-19 or vaccines on thyroid nodule diagnostics.

COVID-19: detection methods in post-mortem samples

COVID-19 identification is routinely performed on fresh samples, such as nasopharyngeal and oropharyngeal swabs, even if, the detection of the virus in formalin-fixed paraffin-embedded (FFPE) autopsy tissues could help to underlie mechanisms of the pathogenesis that are not well understood.

The gold standard for COVID-19 detection in FFPE samples remains the qRT-PCR as in swab samples, contextually other methods have been developed, including immunohistochemistry (IHC), and in situ hybridization (ISH). In this manuscript, we summarize the main data regarding the methods of COVID-19 detection in pulmonary and extra-pulmonary post-mortem samples, and especially the sensitivity and specificity of these assays will be discussed.

Significance of Furin Expression in Thyroid Neoplastic Transformation

Angiotensin-Converting Enzyme 2 (ACE2), Transmembrane Serine Protease 2 (TMPRSS2), and Furin were known to be key players in the SARS-CoV-2 infection, and the thyroid gland was revealed to be one of the relevant targets of the virus. Regardless of the viral infection, the expression of these molecules in the thyroid gland and their putative role in the neoplastic transformation of the thyrocytes has not been thoroughly explored. In this work, we aimed to characterize the mRNA and protein expression pattern of ACE2, TMPRSS2, and Furin in a series of patients with thyroid lesions. Our main results revealed a significantly decreased expression of ACE2 mRNA in the thyroid neoplasms in comparison to normal adjacent tissue. Furin mRNA was significantly increased in thyroid neoplasms when compared to normal adjacent tissue. In addition, a higher Furin mRNA level in thyroid carcinomas was associated with the presence of lymph node metastasis. Furin mRNA expression revealed a high discriminatory power between adjacent tissue and neoplasms. Protein expression of these molecules did not correlate with mRNA expression. Our study shows the mRNA downregulation of ACE2 and overexpression of Furin in thyroid neoplasms. Further studies are required to clarify if Furin expression can be a potential diagnostic indicator in thyroid neoplasia.

Painless thyroiditis incidentally diagnosed following SARS-CoV-2 infection

A euthyroid woman in her 50s with papillary thyroid cancer and primary hyperparathyroidism was referred to our hospital for surgery. Her surgery was scheduled for 4 months later but was postponed because she was diagnosed with COVID-19. Five months after the first visit, she was admitted to our hospital to undergo the planned thyroid lobectomy and parathyroidectomy. Her blood tests on admission showed thyrotoxicosis, with negative thyroid-stimulating hormone receptor and thyroid-stimulating antibody. Notably, her anti-thyroglobulin antibody and anti-thyroid peroxidase antibody, which were originally negative, became positive after SARS-CoV-2 infection. She was diagnosed with painless thyroiditis. Her general condition and vital signs were stable, and the surgery was cautiously performed. Histopathological examination of the resected thyroid revealed papillary thyroid carcinoma, and the findings were consistent with painless thyroiditis. Her postoperative course was uneventful, and her thyroid function improved 2 weeks after the operation.