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.