Azadeh Darabi - Assistant Professor of Pediatrics, Department of Pediatrics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Javad Mohamadi taze abadi - Department of Radiology, Dr. Shariati Hospital, Mashhad University Medical Sciences, Mashhad, Iran.
Hassan Birjandi - Department of Pediatrics, Division of Pediatric Congenital Cardiology, Mashhad University of Medical Sciences, Mashhad, Iran.
Zahra Mousavi Emadi - Department of Pediatrics, Mashhad University of Medical Sciences, Mashhad, Iran.

Background Kawasaki disease (KD) also known as mucocutaneous lymph node syndrome is the febrile and self-limited vasculitis that occurs in children of all ages, especially younger than five years of age. Here, we describe a case of Kawasaki disease with coronary artery aneurysm and a big clot in LV with a diameter of 1.5 cm. Case Presentation In February 2019, a 10-month-old boy with a complaint of weakness and lethargy was referred to Imam Reza hospital in Mashhad (Iran). The patient has had coughs with no response to drug treatment for the past four months. Gallop rhythm was present in heart auscultation. Hepatomegaly was observed in physical examination. No lymphadenopathy was seen, but scalded skin was observed. On the second day of hospitalization in our center, he developed non-purulent bilateral conjunctivitis, strawberry tongue, and maculopapular rashes on the body and distal parts of the limbs. Echocardiography showed dilation of the heart chamber, blood clot in the left ventricle (LV) with the size of 1.5 cm, moderate to severe tricuspid regurgitation (TR), giant aneurysm (0.8 cm) in the left anterior descending coronary artery (LAD), right coronary artery (RCA) aneurysm (0.6 cm), and decreased ejection fraction (EF). Conclusion Kawasaki disease must be considered in the differential diagnosis of patients presenting symptoms of infection including fever and weakness, especially in infants. Early diagnosis of Kawasaki disease can lower the chance of complication including coronary artery aneurysms. Therefore, this disease must be permanently considered in patients (especially in infants) with long-term fever without a typical presentation of Kawasaki to avoid severe heart complications.

Coronary artery aneurysm, giant thrombosis, Kawasaki disease