Subacute Thyroiditis after COVID-19: A Literature Review.

Subacute thyroiditis (SAT), potentially caused by severe acute respiratory syndrome coronavirus 2 infection, has been reported as a complication of COVID-19 since 2020. The clinical characteristics and outcomes of SAT after COVID-19 remain incompletely defined. Therefore, we aimed to collect and survey case reports of SAT after COVID-19. We performed a systematic search of PubMed/MEDLINE, Web of Science, and Google Scholar. The keywords and MeSH terms used for the searches were "subacute thyroiditis" and "COVID-19." A total of 38 patients from 26 case reports, case series, and letters on SAT associated with COVID-19 were included and analyzed. The most frequent SAT symptom was neck pain (27 cases), followed by fever (22 cases). Of the 25 cases with information on the duration between onset of COVID-19 symptoms and onset of SAT symptoms, the shortest was simultaneous occurrence, and the longest was 4 months. In most cases, patients developed SAT at several days or weeks after the onset of COVID-19. All patients with SAT recovered with no severe complications or sequelae. Clinicians should be aware of the possibility of SAT development in patients with neck pain and fever following COVID-19. Further research is necessary to determine the relationship between SAT and COVID-19.

Rapid progression of marginal zone B-cell lymphoma after COVID-19 vaccination (BNT162b2): A case report

B-cell lymphomas are neoplastic diseases occasionally associated with chronic inflammation. mRNA vaccines for coronavirus disease 2019 (COVID-19) induce inflammatory responses, which often lead to fever and lymphadenopathies indistinguishable from lymphomas. Although both lymphadenopathies and lymphomas can be influential, the correlation between them is unclear. Herein, we present the first case of marginal zone B-cell lymphoma following mRNA COVID-19 vaccination. An 80-year-old Japanese woman presented with a right temporal mass that appeared the morning after she was administered her first mRNA COVID-19 vaccination (BNT162b2). The mass gradually decreased in size but persisted over 6 weeks after her first vaccination (3 weeks after her second vaccination). At her first visit to our hospital, ultrasound revealed the size of the mass to be 28.5 × 5.7 mm, and computed tomography revealed multiple lymphadenopathies in the right parotid, submandibular, jugular, and supraclavicular regions. Initially, we suspected head-and-neck benign lymphadenopathy as a side effect of vaccination. Nine weeks later, the number of swollen submandibular and parotid glands increased, and the lymph nodes further enlarged. Finally, the right temporal mass was diagnosed as marginal zone B-cell lymphoma based on immunohistochemical and flow cytometry findings of biopsy specimens. Our findings suggest that although 4–6 weeks of observation for lymph node inflammation after the second vaccination is recommended, malignancy should also be considered in the differential diagnosis of lymphadenopathy following vaccination.