Intravenous Immunoglobulin Resistant Incomplete Kawasaki Disease in a 4-Month-Old Infant: A Case Report

The diagnosis of Incomplete Kawasaki disease (KD) is challenging. Approximately 20% of patients exhibit resistance to initial intravenous immunoglobulin (IVIG) therapy, termed IVIG-resistant KD, which is associated with a markedly increased risk of coronary artery aneurysms and long-term cardiovascular complications. We report a 4-month-old female infant who presented with 8 days of fever, bulging anterior fontanelle, elevated inflammatory markers, thrombocytosis, anemia, and leukocytosis. Echocardiography revealed left main coronary artery (LMCA) dilation (Z-score: 2.9), confirming incomplete KD with coronary involvement. Based on high-risk criteria augmented initial therapy with IVIG, prednisolone, and aspirin was initiated. Despite this, the fever persisted and coronary dilation progressed, confirming IVIG resistance. A second IVIG dose with intravenous methylprednisolone pulse therapy led to defervescence and echocardiographic improvement, with normalization of LMCA dimensions on follow-up. Early identification of high-risk incomplete KD, timely initiation of augmented therapy, and vigilant follow-up are critical in preventing coronary complications.