. 2022 Mar 31;28:e01493.
doi: 10.1016/j.idcr.2022.e01493. eCollection 2022.
A young child with pediatric multisystem inflammatory syndrome successfully treated with high-dose immunoglobulin therapy

Yosuke Mohri 1 , Mariko Shimizu 1 , Tadao Fujimoto 1 , Yuki Nishikawa 1 , Akiko Ikeda 1 , Yusuke Matsuda 2 , Taizo Wada 2 , Chiharu Kawaguchi 1



Pediatric multisystem inflammatory syndrome (MIS-C) is a disease that presents mainly in older children after coronavirus disease 2019 (COVID-19) and is associated with Kawasaki-like symptoms and multiple-organ failure. The number of cases of MIS-C has increased since April 2020, with reports mainly from Europe and the United States. The reason is unclear, but few cases of MIS-C have been reported in Asian countries, including Japan. No treatment has been established for MIS-C. In this study, we report the case of a young boy treated with IVIg for MIS-C by measuring the cytokine profile over time. A 4-year-old boy presented with Kawasaki disease-like symptoms 28 days after a positive result from polymerase chain reaction test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), meeting the World Health Organization criteria for MIS-C diagnosis. Blood tests showed lower levels of C-reactive protein and ferritin, and no decrease in lymphocyte count (<1000/μL) or more increase in fibrinogen than those reported in Japan for MIS-C in school-aged children and older. Neopterin, interleukin (IL)-6, IL-18, soluble tumor necrosis factor receptor (sTNF-R)I and sTNF-RII were all high at disease onset, but neopterin, IL-6, and sTNF-RII rapidly decreased with fever resolution after the second dose of IVIg, while IL-18 and sTNF-RI decreased bimodally. As far as we can determine, this case represents the youngest identified in Japan. The key point of difference between MIS-C and Kawasaki disease is older age in MIS-C, but attention is also needed in infants.

Keywords: COVID-19, coronavirus disease 2019; Cytokine, intravenous immunoglobulin (IVIg); IVIg, intravenous immunoglobulin; Kawasaki disease; MIS-C/PIMS, multisystem inflammatory syndrome in children/ pediatric inflammatory multisystem syndrome; Multisystem inflammatory syndrome in children (MIS-C); SARS-CoV-2.