Kawasaki syndrome (KS) is an acute, febrile, self-limited, infectious, multisystem vasculitis, which occurs in young children. Fever is often prolonged, and coronaryaneurysms may lead to myocardial infarction and death.
Kawasaki syndrome has a peak incidence between 1 and 2 years of age. The disease is rare in children older than 8 years old, and it is uncommon before 3 months of age.
Boys are affected more often than girls by a ratio of 1.5 to 1.
Kawasaki syndrome is a multisystem vasculitis with a predilection for the coronary arteries, associated with pancarditis and pericarditis. Death during this phase is usually caused by an arrhythmia, although fatal heart failure may sometimes occur.
10 to 40 days from the onset of fever, the most common cause of death in untreated children is myocardial infarction caused by coronary aneurysms. After 40 days, healing and stenosis of the post-aneurysmal coronary artery develops.
Abrupt onset of high but remittent fever between 38 and 41 degrees Celcius is characteristic of KS.
Within 2 to 5 days, the child develops other diagnostic signs of KS:
- Conjunctival injection
- mouth changes
- an erythematous rash
- changes in the hands and feet
- unilateral cervical lymphadenopathy
Eye involvement consists of conjunctival injection and photophobia.
The lips are initially bright red, progressing over 3 days to swelling, cracking, and bleeding. Prominent papillae on the tongue create a strawberryappearance, and the oral cavityand pharynxis diffuselyerythematous.
The skin rash is deeply erythematous with slightly raised margins, varying in size from 2 to 3 mm papules to large plaques covering several centimeters. The rash often is urticarial and may be intensely pruritic. The rash frequently affects the face, often forming a mask-like area around the eyes, nose, and mouth. It may be distributed more prominently on the trunk or on the extremities.
Firm, indurative edema of the hands and feet and diffuse red-purple discoloration of palms and soles develop.The edema is sharplydemarcated at the wrists and around the sides of the hands and feet.
Ten to 20 days after the onset of fever, in early convalescence, desquamation starts just under the fingernails and toenails and proceeds to involve the entire palm and sole.
Kawasaki Syndrome : Diagnostic Criteria
Fever for >5 days (usually >102°F)
At least four of five features :
Bilateral conjunctival injection
Cervical adenitis (unilateral >1.5 cm diameter, non-fluctuant)
Rash (truncal, perineal accentuation, polymorphous but nonvesicular)
Inflamed oral mucosae (fissured lips, strawberry tongue)
Hand and feet inflammation (periungual peeling around 14-21 days)
No alternate diagnosis
Fever plus 3/5 criteria are diagnostic when coronary abnormalities are present.
Extreme irritability and emotional lability is common.
Mild cerebrospinal fluid pleocytosis occurs in 25%. The CSF cell count is between 50 and 150/mm3 and is mononuclear. Protein levels are normal to slightly elevated, and glucose level is normal.
Urethritis is present in 60% and is characterized by sterile pyuria. Red blood cells may be detected.
Severe abdominal pain occurs in 20% in the first few days, and it may be associated with elevated amylase and lipase levels.
Liver involvement occurs in 40%; 10% have a bilirubin level >2 mg/dL. The direct fraction is elevated.
Tachycardia with gallop rhythm is present in 60%, and congestive heart failure occurs in 20%. Thirty percent have a pericardial effusion, and 30% have tricuspid insufficiency.
Prolongation of the PR interval and first-degree heart block are very common, but more significant arrhythmias are rare. Coronary artery aneurysms develop in 18-25%.
The differential diagnosis includes staphylococcal toxic shock syndrome, scarlatiniform erythroderma, streptococcal scarlet fever, staphylococcal scalded skin syndrome, measles, febrile viral exanthems, hypersensitivity reactions (Stevens-Johnson syndrome), and juvenile rheumatoid arthritis.
KS should be considered in all young children who have a fever of unknown origin, or fever and severe lymphadenopathy, rash, conjunctival injection, hand and feet changes, and mouth changes.
Erythrocyte sedimentation rate, C-reactive protein, and alpha-1-antitrypsin are elevated. White blood cell (WBC) count is elevated, with a polymorphonuclear cell predominance. Bacterial cultures should be drawn to exclude bacterial infection.
Platelet counts areelevated, peaking at 650,000-2,000,000/mm3 between days 10-20.
Mild-to-moderate anemia usually is present. Bilirubin is elevated in 10%, and liver enzymes are moderately elevated in the first week in 40%. Hypoalbuminemia is common. Urinalysis shows pyuria in 60%.
Treatment of Kawasaki syndrome
Intravenous gamma globulin.
As soon as KS is diagnosed, a baseline echocardiogram is obtained and IVIG 2 g/kg is given in an 8-to 12-hour infusion. Heart rate and blood pressure should be monitored during the infusion.
High-dose aspirin therapy is started on the same day as IVIG. The aspirin dosage is 100 mg/kg/day until a few days after defervescence or until the 14th day of illness. This is followed by a daily dose of 3 to 5 mg/kg until the ESR and platelet counts return to normal, usually after 8 weeks.
Cardiac evaluation and monitoring
Serial echocardiograms should monitor the coronary arteries, valves, and ventricles.
Electrocardiography is useful in the acute stage to evaluate heart block or myocarditis, QRS amplitude reduction, T wave changes, or QT interval changes.
KS usually is self-limited; however, cardiac damage may be serious. Twenty percent of all patients not treated with IVIG develop coronary artery aneurysms, appearing 7 days to 4 weeks after the onset of KS.