A 14-Year-Old Boy With Neck Pain, Fevers, and Diffuse Erythematous Rash.

A previously healthy 14-year-old boy developed right-sided neck pain, tachycardia, a diffuse erythematous rash, and subjective fevers over 2 days. He sought medical attention in a local urgent care clinic, where he had a negative Sars-CoV-2 antigen test and was referred to the local emergency department (ED) for persistent tachycardia and further workup. After fluid resuscitation, his tachycardia was not improved, so he was admitted to the Pediatric Hospital Medicine Service. Physical examination showed large areas of erythema and erythroderma of multiple body sites, perioral sparing, increased erythema in flexor skin folds, posterior soft palate petechiae, and a white strawberry tongue. There was a small, tender lesion with surrounding erythema without discharge on his right neck thought to be a possible entry point for infection. Laboratory results showed thrombocytopenia, normal white blood cell count, normal hemoglobin concentration, absolute lymphopenia, and an elevated C-reactive protein (CRP) to 130 mg/L. He was started on intravenous fluids and antibiotics for a presumed infectious cause of the rash and laboratory findings. The next morning, an expanded diagnostic workup was undertaken including electrocardiogram, echocardiogram, ferritin, triglycerides, liver enzymes, lactate dehydrogenase (LDH), brain natriuretic peptide, coagulation studies, and fibrinogen. With treatment and supportive care, his tachycardia and energy improved, so he was discharged with oral antibiotics and follow-up with the Infectious Disease Clinic in 2 days. When seen in follow-up, he was immediately admitted to the hospital for worsening fatigue, tachycardia, and new findings that prompted multiple consultations, and transfer to pediatric critical care services.