COVID-19 in children and adolescents: MIS(-C)-taken diagnoses

Multisystem inflammatory syndrome in children (MIS-C) is an inflammatory condition associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is characterized by fever, gastro-intestinal symptoms, cardiovascular complications, conjunctivitis, skin involvement, elevated inflammatory markers, and coagulation abnormalities. The current ongoing COVID-19 pandemic causes an increased alertness to MIS-C. In combination with the heterogeneous clinical spectrum, this could potentially lead to diagnostic blindness, misdiagnosis of MIS-C, and overtreatment with expensive IVIG treatment. This report demonstrates the challenge of accurately distinguishing MIS-C from other more common inflammatory pediatric diseases, and the need to act with caution to avoid misdiagnoses in the current pandemic. We present a case series of 11 patients suspected of MIS-C based on the current definitions. Three of them were eventually diagnosed with a different disease. Conclusion: Current definitions and diagnostic criteria lack specificity which potentially leads to misdiagnosis and overtreatment of MIS-C. We emphasize the need to act with caution in order to avoid MIS(-C)-taken diagnoses in the current pandemic. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00431-022-04562-0.