Definition
Diagnostic Criteria
Key History
Key Physical Exam
Risk Factors for Kawasaki Disease
Differential Diagnosis
Diagnostic Testing
Clinical Risk and Safety Pearls
Treatment
Complications
Kawasaki disease is an acute, self-limited, multisystem vasculitis with unknown etiology that is diagnosed clinically in children with fever. The most significant vasculitis involves the coronary arteries, which are involved in about 20% of patients. No one single microbial agent or environmental toxin has been proven as causative. The etiology is unknown, but the epidemiology and clinical picture suggest an inciting infection with an abnormal immune response.
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Clinical criteria have been established for the diagnosis:
Diagnostic criteria for Kawasaki disease (KS) have been established. They include fever of higher than 38.5ºC (103.1ºF) for at least 5 days, and 4 of the following 5 criteria are noted:
- Bilateral nonexudative conjunctival injection.
- Changes in lips, tongue or oral mucosa (injection drying, fissuring, red
strawberry
tongue).
- Changes in peripheral extremities (edema, erythema, desquamation).
- Rash, primarily on the trunk. May be maculopapular, scarlatiniform, or Erythema
multiforme-like.
- Cervical lymphadenopathy (at least one node greater than or equal to 1.5 cm in
diameter).
These criteria are not perfect, with less than 100% sensitivity and specificity.
Children who do not meet all the criteria may have an atypical or incomplete case
of KS. Also, children who meet all the criteria may have another diagnosis.
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- Begins abruptly, lasts an average of 11 days. Acute phase days 1–11.
- Fever: Typically lasting at least 5 days, remittent, > 38.5ºC (103.1ºF)
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- Irritability
- Lethargy
- Intermittent colicky abdominal pain
- Rash
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- Bilateral conjunctival injection (not associated w/exudates)
- Injected or fissured lips, injected pharynx or strawberry tongue
- Erythema of palms/soles, or edema of hands/feet (acute phase)
- Periungual desquamation (convalescent phase)
- Polymorphous rash
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- Maculopapular/scarlatiniform rash on trunk
- Cervical adenopathy
- Erythematous oral mucosa
- Desquamation of hands and feet
- Other findings in cardiovascular, respiratory, musculoskeletal, GI,
GU and nervous systems
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- Japanese descent more than African Americans/Filipinos more than Caucasian
- Age less than 5 years with peak incidence 18 to 24 months
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- Cases appear year-round – most often spring or winter
- Most commonly seen in U.S. and Japan
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- Adenovirus
- Echovirus
- Epstein-Barr virus
- Measles
- Mercury hypersensitivity reaction
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- Rocky mountain spotted fever
- Stevens-Johnson syndrome
- Toxic epidermal necrolysis
- Toxic shock syndrome
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Text / literature information and recommendations include:
- Lab tests are not diagnostic but may be obtained to rule out other disorders.
- CBC – May show anemia with a left shift in the acute phase. Children often have normocytic, normochromic anemia.
- Platelets: Thrombocytosis in 2nd week, up to
1,000,000/mm3.
- LFTs, bilirubin – 30% of patients have mild to moderate elevation of
transaminases.
Some may develop jaundice from hydrops of the gallbladder.
- UA – WBCs if clean catch. WBCs are of urethral origin and may be missed on
catheterized
specimens. Leukocyte esterase is negative.
- ANA
- RF
- ESR - Elevated
- CRP - Elevated
- Pharyngeal and blood cultures
- Cardiac markers: CKMB and troponin
- Lumbar puncture – CSF can show elevated white cell counts.
- Arthrocentesis of involved joints demonstrates 125,000 to 300,000 white
cells/mm3.
- Imaging
- CXR: Evaluate for CHF and infiltrates.
- Echocardiography: This is the primary imaging modality to assess for coronary artery abnormalities. It should be performed at diagnosis, 2 weeks, and 6-8 weeks after the onset of illness. The American College of Rheumatology/Vasculitis Foundation recommends echocardiography to screen for coronary aneurysms and other cardiac involvement.
- ECG: Evaluate for arrhythmias.
- Cardiac Catheterization: Evaluate for aneurysm.
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- In infants < 6 months of age, prolonged fever and irritability may be the only clinical manifestations.
- Delayed diagnosis is common in older children and adolescents.
- Fever and pyuria in an infant or young child can be mistakenly attributed to a UTI, and later development of rash, red eyes and red lips to an antibiotic reaction.
- Diagnosis can be overlooked in an infant with prolonged fever/irritability and a culture-negative CSF pleocytosis suggestive of aseptic meningitis.
- Cervical lymphadenitis may be misdiagnosed as bacterial adenitis.
- Patients with shock may be misdiagnosed with bacterial sepsis or toxic shock syndrome.
- Risk factors associated with increased risk of coronary artery abnormalities include late diagnosis and delayed treatment with IV immunoglobulin; age < 1 or > 9; male sex; fever ≥ 14 days; serum Na < 135 mEq/L; hematocrit < 35%; WBC> 12,000mm³.
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The treatment for Kawasaki disease primarily involves intravenous immunoglobulin (IVIG) and aspirin. According to the American Heart Association guidelines, the standard initial therapy is IVIG at a dose of 2 g/kg administered as a single infusion. This treatment should ideally be initiated within the first 10 days of illness, and if possible, within the first 7 days.
Aspirin is also a critical component of the treatment regimen. Initially, high-dose aspirin (80-100 mg/kg/day) is given during the acute febrile phase. Once the fever subsides, the dose is reduced to low-dose aspirin (3-5 mg/kg/day) until follow-up echocardiograms confirm the absence of coronary abnormalities.
For patients who do not respond to the initial IVIG treatment (approximately 10%-20% of cases), several options are available:
- Repeat IVIG: A second dose of IVIG (2 g/kg) is often administered.
- Corticosteroids: Adjunctive therapy with corticosteroids, such as a 3-day course of intravenous pulse methylprednisolone (30 mg/kg/day), has shown benefits, particularly in patients at high risk for IVIG resistance.
- Tumor Necrosis Factor (TNF)-α Inhibitors: Agents like infliximab have been used in refractory cases.
For patients with coronary artery abnormalities, additional antiplatelet or anticoagulant therapy may be required. Low-dose aspirin or clopidogrel is recommended for mild-to-moderate coronary involvement, while warfarin or low-molecular-weight heparin may be necessary for those with giant aneurysms.
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- 20% to 25% of patients develop cardiovascular sequelae (coronary artery aneurysms,
myocardial infarction, myocarditis).
- Infants less than one year of age with KD have the highest risk of cardiac
complications.
- Patients with fever for more than 16 days or with recurrence have a higher risk
of developing an aneurysm.
- Coronary artery aneurysms occur in 20% to 25% of untreated children, while only 4%
of adequately treated patients develop aneurysms.
- Nonvascular complications
- Acute renal failure
- Abdominal: gallbladder hydrops, paralytic ileus, appendicular vasculitis
- Behavioral changes
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