Multisystem Inflammatory Syndrome in Adults Presenting as Retropharyngeal Phlegmon

Multisystem inflammatory syndrome in adults presents with extrapulmonary organ dysfunction in patients with a recent COVID-19 infection. A 22-year-old man with a history of ataxia with vitamin E deficiency and recent asymptomatic COVID-19 infection presented with retropharyngeal edema treated as phlegmon. He developed cardiac dysfunction and required vasopressor support with evidence of high inflammatory markers. Multisystem inflammatory syndrome in adults was diagnosed, and he rapidly improved with intravenous (IV) corticosteroids. Multisystem inflammatory syndrome in adults can rarely present with retropharyngeal phlegmon. We identified 2 reported cases in adults and 5 in children with an age range of 4 to 51 years. COVID-19 infection was established in all cases but was often previously unknown. All patients recovered with IV corticosteroids with or without IV immunoglobulin. In conclusion, multisystem inflammatory syndrome in adults can present with retropharyngeal edema, and previous COVID-19 infection may not be apparent.