Introduction: Our case is unique because the differential diagnosis was a challenge. At first, the patient presented with septic shock and multi-organ failure in the context of a suspected lymphoproliferative syndrome. Once the lymphoproliferative process had been ruled out, hemophagocytic syndrome due to COVID-19 infection was suspected, so he is probably one of the few patients with such an exhaustive study that could contribute to our understanding of COVID-19. We followed therapeutic guidelines that differ from the usual, using adrenalin and levosimendan. Corticosteroids helped to modulate the cytokine storm. Case report: A 16-year-old adolescent was admitted to the intensive care unit with fever, diarrhea, multiorgan failure and septic shock. He was IgG positive for COVID-19 and IgM negative. Thoraco-abdominal computed tomography demonstrated multiple para-aortic and peri-pancreatic lymphadenopathy and acute respiratory distress syndrome. The first suspected diagnosis was a lymphoproliferative syndrome and bacterial infection. The second possibility was a hemophagocytic syndrome in a patient recovering from COVID-19. He was treated with broad spectrum antibiotics because the differential diagnosis was difficult, and we removed them when the microbiological screening was negative. During the course of the disease he presented with severe biventricular dysfunction, probably due to the cytokine storm, so we used inotropic drugs (adrenaline, levosimendan). Infection with Salmonella species group B was diagnosed later, when the patient was in the Internal Medicine ward, although he was asymptomatic. Conclusion: The severity of COVID-19 infection ranges from mild to severe, causing serious disease in some people. Although the pathophysiology is not well known, it seems that in some cases an immune storm is triggered, and it is related to more serious and prolonged disease. In our case, heart failure was important, because it could have worsened the prognosis. Fortunately, the response to levosimendan and corticosteroids was adequate and he recovered favorably until discharge.