Trismus and Retropharyngeal Inflammation Revealing Multisystem Inflammatory Syndrome in Children: A Case Report.

Multisystem inflammatory syndrome in children (MIS-C) is a severe post-infectious hyperinflammatory condition associated with SARS-CoV-2 infection. We report a case of a previously healthy 14-year-old girl who presented with fever, painful cervical lymphadenopathy, progressive trismus, and a diffuse erythematous rash. On admission, she exhibited circulatory shock with severe hypotension, markedly elevated inflammatory markers, acute kidney injury, and severe myocardial dysfunction. Cervical computed tomography revealed retropharyngeal inflammatory edema associated with cervical lymphadenopathy. SARS-CoV-2 serology showed positive IgG and negative IgM antibodies. Based on the clinical presentation, laboratory findings, and multisystem involvement, a diagnosis of MIS-C was established. Treatment with intravenous methylprednisolone pulses followed by oral corticosteroids, aspirin, and supportive therapy resulted in rapid clinical and laboratory improvement, including complete resolution of trismus, recovery of renal function, and normalization of cardiac function. Follow-up echocardiography demonstrated complete recovery of left ventricular systolic function, and the patient remained asymptomatic at three-month follow-up. This case highlights an unusual presentation of MIS-C with trismus and retropharyngeal inflammatory changes. Awareness of this rare manifestation may facilitate early diagnosis and prompt treatment, thereby preventing potentially life-threatening complications.