Atypical Kawasaki Disease with Hepatosplenomegaly in a 6-Month-Old Infant: A Case Report

Abstract

Kawasaki disease (KD) is an acute, self-limiting systemic vasculitis that predominantly affects children younger than 5 years and may involve the coronary arteries. In young infants, incomplete or atypical presentations may complicate early recognition, particularly when classical clinical criteria are not fulfilled. This case describes a 6-month-old full-term male infant weighing 7.8 kg who presented with a 9-day history of fever and a generalised erythematous maculopapular rash that developed on the second day of illness. Only one principal clinical feature of KD, the polymorphous rash, was present. Laboratory investigations showed leukocytosis with lymphocytosis, thrombocytosis, an elevated C-reactive protein level, anaemia with reduced mean corpuscular volume and mean corpuscular haemoglobin, and proteinuria. Abdominal ultrasonography demonstrated hepatosplenomegaly, with liver and spleen measurements of 9.5 cm and 9.7 cm, respectively, while two-dimensional echocardiography showed no cardiac involvement or coronary artery aneurysms. Based on the prolonged fever, inflammatory findings, thrombocytosis, and hepatosplenomegaly, atypical Kawasaki disease was diagnosed. The infant received intravenous immunoglobulin, aspirin, methylprednisolone, and furosemide. Fever resolved and the clinical condition and inflammatory markers improved, and the infant was discharged after clinical stabilisation with follow-up advice. This case highlights the importance of considering atypical KD in infants with prolonged fever and unexplained hepatosplenomegaly despite incomplete classical features.