Abstract

Some of the articles being published during the severe acute respiratory syndrome–coronavirus (SARS-CoV)-2 pandemic highlight a link between severe forms of coronavirus disease 2019 (COVID-19) and the so-called cytokine storm, also with increased ferritin levels. However, this scenario is more complex than initially thought due to the heterogeneity of hyperinflammation. Some patients with coronavirus 2019 disease (COVID-19) develop a fully blown secondary haemophagocytic lymphohistiocytosis (sHLH), whereas others, despite a consistent release of pro-inflammatory cytokines, do not fulfil sHLH criteria but still show some features resembling the phenotype of the hyperferritinemic syndrome. Despite the final event (the cytokine storm) is shared by various conditions leading to sHLH, the aetiology, either infectious, autoimmune or neoplastic, accounts for the differences in the various phases of this process. Moreover, the evidence of a hyperinflammatory microenvironment provided the rationale to employ immunomodulating agents for therapeutic purposes in severe COVID-19. This viewpoint aims at discussing the pitfalls and issues to be considered with regard to the use of immunomodulating agents in COVID-19, such as timing of treatment based on the viral load and the extent of cytokine/ferritin overexpression. Furthermore, it encompasses recent findings in the paediatric field about a novel multisystem inflammatory disease resembling toxic shock syndrome and atypical Kawasaki disease observed in children with proven SARS-CoV2 infection. Finally, it includes arguments in favour of adding COVID-19 to the spectrum of the recently defined ‘hyperferritinemic syndrome’, which already includes adult-onset Still’s disease, macrophage activation syndrome, septic shock and catastrophic anti-phospholipid syndrome.