Pathophysiology
Idiopathic post-infectious dysregulated immune activation targeting medium-sized arteries. IL-1, IL-6 and TNF drive vasculitis; coronary arteries particularly vulnerable, forming aneurysms 2-4 weeks after onset.
Sources: AHA Kawasaki Disease Scientific Statement (Circulation 2017;135:e927); McCrindle 2017 AHA Update; NICE Kawasaki Disease Overview
Clinical presentation (CRASH & burn)
Fever >=5 days plus >=4 of: bilateral non-exudative conjunctivitis; mucosal changes (strawberry tongue, cracked red lips); polymorphous rash; extremity changes (erythema, oedema, later periungual desquamation); cervical lymphadenopathy >1.5 cm (usually unilateral).
Diagnosis
Clinical - support with ESR/CRP elevation, thrombocytosis after week 2, sterile pyuria, transaminitis. Baseline and follow-up echocardiogram (2 and 6 weeks) to detect coronary aneurysms.
Management
IVIG 2 g/kg single infusion + high-dose aspirin (30-50 mg/kg/day until afebrile 48 h, then low-dose 3-5 mg/kg/day for 6-8 weeks). IVIG-resistant cases: second IVIG dose, IV methylprednisolone, or infliximab. Long-term aspirin/anticoagulation for coronary aneurysms.
Prognosis
Untreated coronary aneurysms 25%; IVIG within 10 days cuts risk to 5%. Giant aneurysms carry lifelong thrombotic risk.
