Pathology of Kawasaki disease in the healed stage. Relationships between typical and atypical cases of Kawasaki disease.

To define the pathological features of Kawasaki disease (KD) in the healed stage (over 40 days of illness), 69 autopsied infants with clinically typical KD (25 in the healed stage and 38 in the acute stage) and atypical KD (four in the healed stage and two in the acute stage) were examined. In the medium-sized arteries with coronary aneurysm in KD, panvasculitis was evident in the acute stages, while scar formation was noted in the healed stage. Thrombi, marked intimal thickening, marked stenosis, and recanalization were seen in the coronary arteries. In KD without aneurysm, acute inflammation was localized in the intima and the perivascular area of the coronary arteries in the acute stages, but was absent in the healed stage. Although intimal thickening was noted, marked stenosis and thrombi were not evident in KD without aneurysm. In KD with and without aneurysm, acute angiltis in small arteries and micro-vessels and acute inflammation of various organs were noted in the acute stages, but disappeared in the healed stage. Fibrinoid necrosis of the artery was rare in the acute stages and was not noted in the healed stage. Atypical cases of KD showed the same pathological features as those in cases with clinically typical KD. The common cause of death in the healed stage was ischemic heart disease. Old myocardial infarction was noted in 80% of the cases, and acute myocardial infarction was seen In 35%. KD is an acute systemic inflammatory disease and KD without aneurysm is a disease with mild angiitis.