Reactivation of BCG inoculation site in a child with febrile exanthema of 3 days duration: an early indicator of incomplete Kawasaki disease.

Lim, Kimberley Ying Ying; Chua, Mei Chien; Tan, Natalie Woon Hui; Chandran, Suresh

The aetiology of febrile exanthems in children is often difficult to distinguish clinically. A diagnosis of Kawasaki disease (KD) should be considered in infants with exanthematous fever. More perplexing is the increasing incidence of an atypical form of KD. Pathogenesis of KD remains unclear even though an aberrant response of the immune system to an unidentified pathogen is often hypothesised. A 30-fold increase in the incidence of KD in Italy during the SARS-CoV-2 pandemic suggests an immune response to a viral trigger. We report an infant clinically diagnosed with high probability as incomplete KD, who presented with reactivation of the BCG injection site even though fever with rash was only less than 3 days duration. Echocardiography confirmed coronary artery abnormalities and prompt treatment with intravenous immunoglobulin facilitated rapid recovery. Physicians should consider a diagnosis of KD if BCG site reactivation is noted in children presenting with febrile exanthema.