ISSN: 2161-1149 (Printed)
Narvel H1*, Mazzini J1 , Shao D1 , Yakkali S3 , Mehta A1 , Kumar A2
HLH is a rare, life-threatening condition characterized by an ineffective hyper stimulation of the immune system which leads to a pathologic rise in cytokine levels and to a hyper inflammatory state. Many conditions like Macrophage Activation Syndrome (MAS), sepsis, malignancies and even multi-inflammatory response syndrome after COVID 19 infection share overlapping clinical presentation and laboratory findings with HLH. Our review aims to provide updated clinical-practical generalities of HLH in terms of epidemiology, pathophysiology, clinical features, and management particularly in light of COVID19. The etiology of HLH can be classified as familial or secondary/ sporadic. The differentiation of primary and secondary HLH is very important because primary HLH may require different treatment modalities like hematopoietic stem cell transplantation. Since the emergence of the SARS-CoV2 pandemic, the number of reported cases of HLH in patients with COVID19 has progressively increased. A brief overview of the etiology, genetics, and immunology of HLH is also provided. This review also highlights the diagnostic challenges associated with HLH and emphasizes that early identification, low threshold for suspicion, thorough diagnostic work up and multidisciplinary approach are crucial for timely diagnosis and optimal management.