Successful Recovery of a Child with COVID-19-Induced Secondary Hemophagocytic Lymphohistiocytosis

The coronavirus disease 2019 (COVID-19) pandemic has imposed a significant burden worldwide, manifesting as a severe disease and causing mortality even in children. Severe COVID-19 disease is characterized by cytokine storm with progression to secondary hemophagocytic lymphohistiocytosis (sHLH). We describe an 18-month-old boy in Iran, previously healthy, diagnosed with COVID-19-induced sHLH. Three weeks after close contact with COVID-19 confirmed cases, he was admitted with high fever, lethargy, mild respiratory distress, skin rash, and conjunctivitis with swollen eyelids and lips. Laboratory data revealed elevated levels of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and liver enzymes, and mild thrombocytopenia. His clinical condition rapidly deteriorated, with septic shock, hepatosplenomegaly, and respiratory failure. Laboratory tests showed cytopenia, coagulopathy, hyperferritinemia, and hypertriglyceridemia, which met the criteria for sHLH diagnosis. Chest computed tomography (CT) revealed bilateral infiltrations that suggested acute respiratory distress syndrome (ARDS) of COVID-19 that was confirmed by a positive real-time polymerase chain reaction (RT-PCR) test. Therefore, the child was treated with intravenous immunoglobulin (IVIG), glucocorticoid, hydroxychloroquine, lopinavir/ritonavir, and interferon beta-1a. This therapeutic strategy enabled complete recovery from fever, regaining consciousness, weaning from respiratory support, and resolving shock. Serial chest radiographs showed diminishing infiltrations. Sequential physical examinations revealed an overall significant reduction in spleen and liver span. Laboratory data showed rapid improvement from cytopenia and coagulopathy, normalization of liver enzyme levels, and reduction in hyperinflammation markers. Although ARDS is the most common cause of death from COVID-19, other complications such as sHLH may be lethal; thus, early diagnosis and appropriate treatment are necessary for saving patients' lives.