Hyper-inflammation after COVID-19 mARN vaccination: at the crossroads of multisystem inflammatory disease and adult-onset Still's disease. Does terminology matter?

As the pandemic evolves, different facets of the SARS-CoV-2 infection, as well as immunization, with varying complexity and prognostic implications are discovered. One of them is the multisystem inflammatory syndrome (MIS)[1]. Characterized by elevated ferritin levels and hyper-inflammation with vital implications, MIS was proposed as the fifth clinical entity to constitute the “hyperferritinaemic syndromes”, alongside the macrophage activation syndrome (MAS), adult-onset Still’s disease (AOSD), catastrophic anti-phospholipid syndrome and septic shock [2]. Although most reports were related to SARS-COV-2 infection, MIS was recently described in relation to COVID-19 vaccination as well [3]. We hereby report the case of a previously healthy 22-year-old male, who received the first dose of BNT162b2 vaccine on May 1 2021. Thirteen days after vaccination, he developed a hyperinflammatory state, fulfilling the criteria for adult multisystem inflammatory syndrome (MIS-A) [2] (fever, sore throat, myalgias, myocarditis, hepatic injury, maculo-papular rash, diarrhoea, hypotension, and highly elevated inflammatory markers including a procalcitonin level of 33 ng/ml). He was initially admitted in another hospital’s Cardiology department with a diagnosis of acute coronary syndrome. At that moment the patient presented with chest pain, ST elevation on ECG, high troponin level, segmental left ventricular hypokinesia, and mid-range ejection fraction. The coronary angiography was normal,