Granulomatous mesenteric lymphadenitis after three doses of the COVID-19 vaccine

Abstract

Lymphadenopathy related to vaccination has been reported as an adverse effect of mRNA-based COVID-19 vaccines. Most cases are regional lymph nodes near of injection site, with mild-moderate 18 F-fluorodeoxyglucose uptake on positron emission tomography. We report a middle-aged Brazilian man with mesenteric lymphadenitis manifested five days after the third dose of the Pfizer-BioNTech mRNA-based vaccine against COVID-19. The patient had no known risk factors and evolved with rapid clinical improvement. The imaging findings, laboratory determinations, histopathological and microbiological evaluations raised doubts about the hypothesis of an eventual adverse effect of the vaccine. The aim is to call attention to possible rare reactions of SARS-CoV-2 vaccinations.