Background: Coronary artery aneurysm (CAA) in patients with Kawasaki disease (KD) almost always occurs after day 8, and the most early detection report of CAA was in an autopsy case on day 6 after onset. The possibility of CAA formation prior to day 6 has not been documented.
Case report: A 10-month-old Japanese boy presented with a 4-day fever, conjunctival injection, erythema of the lips, erythema of the palms and soles, erythematous rush, and induration at a Bacillus Calmette-Guerin inoculation site. On day 4, echocardiography revealed coronary artery dilatation (right coronary artery [RCA], 4.6 mm; left main trunk [LMT], 4.6 mm; left anterior descending [LAD] artery, 3.4 mm). Laboratory data were as follows: white blood cell count, 19,400/μL; C-reactive protein, 15.2 mg/dL; albumin, 3.2 g/dL; high-density lipoprotein cholesterol, 20 mg/dL, and erythrocyte sedimentation rate, 48 mm/h. He was diagnosed with KD and treated with oral aspirin 30 mg/kg/day and intravenous immunoglobulin (IVIG) 2 g/kg. His fever subsided the next day. On day 17, periungual peeling of the fingers and toes was noted. His fever recurred and he treated with additional IVIG 1 g/kg, after which his fever subsided again. On day 20, the aneurysms had not increased in size (RCA, 3.3 mm; LMT, 3.6 mm; LAD, 2.4 mm). On day 44, although echocardiography showed a mild coronary artery dilatation, a coronary angiogram showed no apparent abnormality. He had no obvious fever or symptoms of KD prior to this course of KD. This case may help clarify the pathophysiology of CAA in patients with KD.