Subacute thyroiditis associated with COVID-19 infection: a report of an increasing entity

In March 2020, the World Health Organization characterized COVID-19 as a pandemic. By May 2021, 37 cases of subacute thyroiditis (SAT) associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had been reported in the literature. We report a patient diagnosed with SAT associated with COVID-19 and review the previously reported cases. A 31-year-old female with no significant previous history developed SAT 5 weeks after SARS-CoV-2 infection. She presented with anterior neck pain and fever. Thyroid function tests revealed hyperthyroidism with slightly increased inflammatory markers. Thyroid ultrasound showed diffuse hypoechoic left lobe and a hypoechoic area in the right lobe. On the fine-needle-aspiration biopsy, large histiocytes, disrupted and normal follicles, and multinucleated giant cells within colloid were seen. Under oral corticosteroid therapy, clinical progression was rapid. Seven weeks later, all thyroid function tests and inflammatory markers normalized. During the recent viral outbreak, clinicians should keep in mind the possibility of SAT after COVID-19, and patients with symptoms of SAT should be tested for SARS-CoV-2.