Abstract
BackgroundCOVID-19, a disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), commonly presents as fever, cough, dyspnea, and myalgia or fatigue. Although the majority of patients with COVID-19 have mild symptoms, some are more prone to serious outcomes, including pneumonia, acute respiratory distress syndrome (ARDS), and even death. Hemophagocytic lymphohistiocytosis (HLH) is a severe, life-threatening inflammatory syndrome associated with intense cytokine release (also known as a “cytokine storm”). Similar to COVID-19, HLH is characterized by aggressive course leading to multi-organ failure.Main textThe purpose of this review article is to draw attention to the possibility of the complication of HLH in patients with the severe course of COVID-19. Indeed, some of the clinical characteristics observed in the more severe cases of COVID-19 are reminiscent of secondary HLH (which can be triggered by infections, malignancies, rheumatological diseases, or autoimmune/immunodeficiency conditions). The pathogenesis of SARS-CoV-2 infection also suggests that HLH or a similar hyperinflammatory syndrome is the cause of the severe course of the infection.ConclusionThe pathogenesis and clinical symptoms of severe COVID-19 indicate that an increased inflammatory response corresponding to HLH is occurring. Therefore, patients with severe COVID-19 should be screened for hyperinflammation using standard laboratory tests to identify those for whom immunosuppressive therapy may improve outcomes.
Highlights
The purpose of this review article is to draw attention to the possibility of the complication of Hemophagocytic lymphohistiocytosis (HLH) in patients with the severe course of COVID-19
The pathogenesis and clinical symptoms of severe COVID-19 indicate that an increased inflammatory response corresponding to HLH is occurring
Patients with severe COVID-19 should be screened for hyperinflammation using standard laboratory tests to identify those for whom immunosuppressive therapy may improve outcomes
Summary
HLH: an aberrant immune response to viral infections The majority of viral infections acquired by nonimmunosuppressed individuals are asymptomatic or result in mild clinical manifestations; for those who are immunocompromised or have an immune disorder, viral infections may result in a life-threatening disease, as occurs in the case of HLH (Table 1) [13]. CRS is another systemic inflammatory response that can be triggered by infections and can present with similar symptoms (e.g., fever, fatigue, headache, rash, arthralgia, myalgia, uncontrolled systemic inflammatory response, and multi-organ failure) and laboratory abnormalities (e.g., cytopenias, elevated creatinine and liver enzymes, abnormal coagulation parameters, and high CRP levels) to HLH [40]. A clinical study to evaluate the efficacy and safety of anakinra and emapalumab (an anti-IFN-γ antibody that is FDAapproved for adult and pediatric patients with primary HLH) in the treatment of hyperinflammatory syndrome associated with severe cases of COVID-19 is currently underway (ClinicalTrials.gov Identifier: NCT04324021) [48]. There are a number of exciting new therapies in the pipeline to combat severe cases of COVID-19
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