Kawasaki disease (KD)
mucocutaneous lymph node syndrome and infantile polyarteritis nodosa, is an acute febrile illness of childhood .
KD is a vasculitis with a predilection for the
coronary arteries.
Approximately 20-25% of untreated children develop coronary artery abnormalities (CAA) including aneurysms.
<5% of children treated with intravenous gammaglobulin (IVIG) develop CAA.
KD is the leading cause of acquired heart
disease in children in most developed countries.
ETIOLOGY:bomb:
The cause of KD remains ((unknown))
but certain epidemiologic and clinical features support an infectious origin.
A genetic role in the pathogenesis of KD seems likely, as evidenced
by the higher risk of KD in Asian children.
linkage studies and genome-wide association studies have identified significant associations between polymorphisms in the ITPKC gene, a T-cell regulator, with increased susceptibility to KD and to more-severe disease.
immunoglobulin G (FCGR2A) have also been identified as significant variants in KD patients.
Pathology:bomb:
KD is a vasculitis affects medium-size arteries.
The coronary arteries are the most commonly involved,also popliteal and brachial arteries.
((A 3-phase process ))to the arteriopathy of KD.
The 1st phase is in the 
1st 2 wk of illness begins in the endothelium and moves
through the coronary wall.
Saccular aneurysms may form from this arteritis.
The 2nd phase is a subacute/chronic vasculitis may last weeks to years .
results in fusiform aneurysms.
The vessels affected by the subacute/chronic vasculitis cause progressive stenosis.
Thrombi may form in the lumen and obstruct blood flow.
CLINICAL MANIFESTATIONS:bomb:
Fever is characteristically 
high (≥38.3°C [101°F]),
unremitting
unresponsive to antibiotics.
The duration of fever without treatment is generally 1-2 wk, but may persist for 3-4 wk.
the 5 principal clinical criteria of KD are:
bilateral nonexudative conjunctival injection with limbal sparing
erythema of the oral and pharyngeal mucosa with strawberry tongue and red, cracked lips;
edema and erythema of the hands and feet; rash of various forms (maculo-papular, erythema multiforme, or scarlatiniform
nonsuppurative cervical lymphadenopathy, usually unilateral, with node size >1.5 cm
(Table 166-1; Figs. 166-1 to 166-4).
Perineal desquamation is common in the acute phase.
Periungual desquamation of the fingers and toes begins(( 2-3 wk ))after the onset of illness .
Gastrointestinal symptoms (vomiting, diarrhea, or abdominal pain) occur in more than 60% of patients, and at least 1 respiratory symptom (rhinorrhea or cough) occurs in 35%.
Other findings
* significant irritability
* urethritis and meatitis with sterile pyuria.
* arthritis.
Small or large joints may be affected, and the arthralgias
KD can be divided into 3 clinical phases:
The acute febrile phase is
fever + acute signs of illness and usually
lasts 1-2 wk.
The subacute phase 🤷
desquamation
thrombocytosis
the development of CAA, the highest risk of sudden death from aneurysms
lasts about 3 wk.
The convalescent phase
begins when all clinical signs have disappeared and continues until (ESR) returns to normal.
typically about ((6-8 )) Wk after the onset of illness.