Lemierre's Syndrome Under the Disguise of COVID-19 Pneumonia: A Case Report and Systematic Review.

Lemierre's syndrome refers to septic thrombophlebitis caused by Fusobacterium necrophorum bacteremia. The incidence of Lemierre's syndrome has risen over the past two decades. This report describes a case of a 31-year-old woman presenting with multifocal pneumonia and uncomplicated parapneumonic effusion, considered as COVID-19 pneumonia initially, then found to have Lemierre's syndrome with Fusobacterium necrophorum bacteremia and right internal jugular vein thrombophlebitis. Her condition improved after four weeks of antibiotics without anticoagulation. The article summarized the history, epidemiology, clinical presentation, differential diagnosis, and treatment of Lemierre's syndrome, the rare but severe complication of bacterial infection. The article also summarized six reported Lemierre's syndrome cases during the COVID-19 pandemic to emphasize the significance of having a broad differential diagnosis for respiratory symptoms, especially in the COVID-19 era.