More than Mucositis: Pediatric RIME Following Co-Infection with SARS-CoV-2 and Mycoplasma pneumoniae—A Case Report and Mini-Review

<b>Background:</b> Reactive Infectious Mucocutaneous Eruption (RIME) is a mucositis-predominant syndrome that usually follows respiratory infections in children. Although <i>Mycoplasma pneumoniae</i> is a well-established trigger, viral pathogens as triggers-especially SARS-CoV-2-have been increasingly reported. RIME is often misclassified as Stevens-Johnson syndrome (SJS), which may lead to inappropriate management. <b>Case Presentation:</b> We describe a 12-year-old previously healthy boy who presented with fever, dry cough, odynophagia, and vomiting for 9 days. On admission, he had severe oral ulcerations, bilateral conjunctivitis, and a non-blanching maculopapular rash. Laboratory tests confirmed co-infection with <i>M. pneumoniae</i> and SARS-CoV-2. Inflammatory markers were mildly elevated. Notably, the patient also developed asymptomatic sinus bradycardia, with no signs of structural heart disease. He was treated with antibiotics, intravenous corticosteroids, and supportive care. His mucosal symptoms improved rapidly, and he was discharged in stable condition on day 7. Follow-up at 12 days showed near-complete resolution of all lesions. <b>Conclusions:</b> This case illustrates several clinically relevant features. First, it highlights a dual infectious trigger-<i>M. pneumoniae</i> and SARS-CoV-2-that may have contributed to a more severe mucosal reaction. Second, the patient developed transient sinus bradycardia without myocardial involvement, suggesting a possible inflammatory autonomic response, rarely reported in RIME. Finally, this case supports the early use of corticosteroids in severe mucosal disease, with good outcomes and no complications. Prompt recognition of RIME, especially in the context of viral-bacterial coinfection, is essential to avoid misdiagnosis and to guide appropriate, multidisciplinary management.