Paediatric multisystem inflammatory syndrome temporally associated with COVID-19 (PIMS-TS), also known as multisystem inflammatory syndrome in children (MIS-C), is a novel hyperinflammatory condition that shares features with Kawasaki disease (KD) and toxic shock syndrome (TSS).1–3 The median age of children with PIMS-TS is approximately 8 years with male sex, obesity and black or Asian ethnicity associated with an increased risk.1 2 Children with PIMS-TS typically have a history of SARS-CoV-2 infection in the weeks preceding presentation.1 2 The clinical phenotype varies and includes fever, gastrointestinal symptoms, cardiac manifestations, conjunctivitis, polymorphous rashes and respiratory failure.1–3 Figure 1 and table 1 report the diagnostic criteria for PIMS-TS and the common features seen in children with the disease. Children with PIMS-TS often resemble children with KD/TSS. Many appear very unwell and require admission to the paediatric intensive care unit.1 2 Initial investigations universally demonstrate evidence of hyperinflammation with C reactive protein levels typically greater than 100 mg/L as well as an elevated erythrocyte sedimentation rate, hyponatraemia, hypertriglyceridaemia, and elevated D-dimer and serum ferritin.1–3 Lymphopaenia is common as are abnormal cardiac biomarkers such as elevated brain natriuretic peptide (BNP) and troponin.1–3

Clinical features of PIMS-TS. CRP, C reactive protein; PIMS-TS, paediatric multisystem inflammatory syndrome temporally associated with COVID-19. Brain natriuretic peptide (BNP), C-reactive protein (CRP)

Diagnostic criteria for PIMS-TS

The principles of management of PIMS-TS include immunomodulation (typically with intravenous immunoglobulins and steroids), supportive care, management of cardiac complications and thromboprophylaxis.3 4 The longer term outcomes from PIMS-TS are unknown. Initial reports suggest that while most measures of cardiac function normalise within 6 months, approximately half of children have ongoing fatigue and poor exercise tolerance.5 Very few children with COVID-19 infection develop PIMS-TS suggesting that PIMS-TS occurs by a combination of a genetic predisposition and an aberrant immune …