RESUMEN
RATIONALE: Macrophage activation syndrome (MAS) is a rare life-threatening condition characterized by cytokine-mediated tissue injury and multiorgan dysfunction. PATIENT CONCERNS: We describe the unique case of young man who developed MAS as the sole manifestation of an otherwise paucisymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. DIAGNOSES: Clinical and biological criteria led to the diagnosis of MAS; cytokine profile was highly suggestive reverse transcription polymerase chain reaction for SARS-CoV-2 in nasopharyngeal swabs was negative, but serum anti-SARS-CoV-2 immunoglobulin A and immunoglobulin G resulted positive leading to the diagnosis of SARS-CoV-2 infection. INTERVENTIONS: The patient was treated with empiric antibiotic and hydroxychloroquine. OUTCOMES: Clinical improvement ensued. At follow-up, the patient is well. LESSON: SARS-CoV-2 infection may trigger develop life-threatening complications, like MAS. This can be independent from coronavirus disease 2019 gravity.