'Breaking' news: A pediatric case of leukocytoclastic vasculitis after SARS-CoV-2 vaccination

ABSTRACT

Case report In May 2021, the European Medicines Agency (EMA) approved the administration of the mRNA BNT162b2 vaccine (Pfizer/BioNTech) in adolescents aged 12-15 years, in the form of a two-doses-primary course three weeks apart, with a booster dose after five months. Few adverse events have been observed in vaccinated children -mainly fever, myalgia, or local edema at the injection site. Conversely, delayed cutaneous reactions are little reported in adults and even rarer in pediatric age. A 12-year-old boy, with no previous cutaneous or autoimmune diseases nor allergic reactions to previous vaccines or drugs, came to our attention because of a cutaneous rash, which started on his right arm two days after his first dose of Pfizer/BioNTech vaccine. The rash was flat, erythematous, and purpuric, with subsequent bruise appearance and spontaneous resolution. Lesions took over on the front side of his arms and shoulders until a month after the vaccine. Urine and blood tests -including blood cell count, flow cytometry, plasma biochemistry, inflammatory index, autoantibodies, coagulation, and platelets aggregation test -did not show significant alterations. Grass pollen monosensitization was detected. Biopsy of the lesions showed 'modest perivascular lymphohistiocytic infiltrate and focal infiltration of vascular walls with swollen endothelium' with 'occasional eosinophils, scattered neutrophil granulocytes, and erythrocytes in interstitial areas,' compatible with leukocytoclastic vasculitis. Epidermidis was undamaged, and the direct immunofluorescence showed fibrinogen deposits in superficial-to-middle dermis vessels. Further tests highlighted a high immune response to the vaccine without previous Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. No therapies were needed, and the boy experienced no other side effects undergoing his second dose. Few leukocytoclastic vasculitis cases after SARS-CoV-2-vaccination have been reported in adults, primarily flares of previously known vasculitis. A role for induced spike glycoprotein as a pseudovirion docking to specific vascular receptors has been suggested, too. To our knowledge, no similar cases were described currently, neither in such young patients nor with such atypical, focal lesions. Further studies are needed to identify the pathogenesis and possibly prevent the onset of this adverse reaction.