ABSTRACT
Kawasaki disease is an acute systemic disease characterized by the predominant lesions of middle and small arteries, alongside destructive and proliferative vasculitis development. The aetiology is currently being discussed. Infectious factors are mostly preferred, in addition, autoimmune mechanisms and genetic heredity are considered. The diagnosis of Kawasaki disease is established by clinical signs; laboratory changes are usually taken into account as are ancillary criteria. The article discusses the clinical case of Kawasaki disease in an 8-year-old boy. Given the variety and inconsistency of the clinical symptoms (the child had four of the five mandatory criteria together with prolonged fever), there was a late diagnosis, namely on day 10 of the disease. Due to the high risk of cardiovascular complications in the differential diagnosis of children with fever lasting more than 3 days should be considered Kawasaki disease, followed by mandatory heart echocardiography during the first 10 days of the disease, especially if the fever is accompanied by the increase of acute phase reactants. When treating children with chronic fever without a specific source, the doctor should be wary of Kawasaki disease, as it can clinically simulate acute respiratory viral disease, the onset of diffuse connective tissue disease, and infectious endocarditis, and can have common features and require differential diagnostics with coronavirus associated multisystem inflammatory syndrome.