Unusual Manifestations of Kawasaki Disease in the COVID Era: A Case Series and Review of the Literature

Kawasaki disease (KD) is an acute medium-vessel vasculitis, mainly affecting infants older than six months and children under five years. It predisposes to the development of coronary artery aneurysms and constitutes the leading cause of acquired heart disease in children. Its diagnosis is based on clinical criteria, namely, fever lasting for ≥ five days together with at least four of the five principal clinical features of the disease. Occasionally, children with KD present with fever, but they fulfill only some of the five principal criteria, and this is described as incomplete KD. Furthermore, "atypical" KD is a term that is usually used for cases that appear with rather unusual clinical manifestations, which complicate clinical judgment and may delay diagnosis and treatment. In this case series, we present four cases of KD with rather unusual clinical features: a five-year-old boy with lobar pneumonia, a six-year-old girl with orange-brown chromonychia appearing on the 10 day of the disease, a 2.5-month-old infant with prolonged fever and urinary tract infection, and an 18-month-old infant with refractory KD and high suspicion of multisystem inflammatory syndrome in children (MIS-C). A literature review on the unusual manifestations of atypical KD was performed to identify clinical findings that must alert the clinician to consider this clinical entity.