What are the symptoms and diagnosis of Kawasaki disease?

Kawasaki Disease: Clinical Symptoms and Diagnostic Features

I cannot provide pictures, but I can describe the characteristic symptoms and diagnostic features of Kawasaki disease in detail to help you recognize this condition.

Classic Diagnostic Criteria

Kawasaki disease is diagnosed clinically by fever lasting at least 5 days plus at least 4 of 5 principal clinical features: oral mucosal changes, bilateral conjunctival injection, polymorphous rash, extremity changes, and cervical lymphadenopathy. 1, 2, 3

Fever Characteristics

• High-spiking fever typically exceeding 39-40°C (102.2-104°F) 2
• Must persist for at least 5 days (day of onset = day 1) 2
• Without treatment, fever continues 1-3 weeks on average 2
• Diagnosis can be made with only 4 days of fever when ≥4 principal features are present, particularly with hand/foot swelling 2

The Five Principal Clinical Features

1. Oral Mucosal Changes 1, 2

• Erythema, dryness, fissuring, peeling, cracking, and bleeding of the lips
• "Strawberry tongue" with erythema and prominent fungiform papillae (indistinguishable from streptococcal scarlet fever)
• Diffuse erythema of the oropharyngeal mucosa
• Important: Oral ulcerations and pharyngeal exudates are NOT seen 1

2. Bilateral Conjunctival Injection 1, 2

• Nonexudative and primarily bulbar
• Limbal sparing is characteristic
• Usually painless 1
• Mild acute iridocyclitis or anterior uveitis may be noted by slit lamp, but rarely associated with photophobia or eye pain 1

3. Polymorphous Rash 2

• Most commonly diffuse maculopapular eruption
• Can take various forms (hence "polymorphous")
• Typically appears early in the illness

4. Extremity Changes 2

• Acute phase: Erythema of palms and soles, edema of hands and feet
• Subacute phase (2-3 weeks): Periungual desquamation beginning under the nail beds of fingers and toes 1

5. Cervical Lymphadenopathy 1, 2

• Least common of the principal features 1, 2
• Usually unilateral and confined to the anterior cervical triangle 1
• Classic criteria: ≥1 lymph node that is ≥1.5 cm in diameter 1, 2
• Lymph nodes are firm, nonfluctuant, not associated with marked erythema of overlying skin 1
• Nontender or only slightly tender 1

Cardiovascular Manifestations

Cardiovascular findings are the leading cause of long-term morbidity and mortality. 1

Clinical Cardiac Findings 1

• Hyperdynamic precordium and tachycardia
• Gallop rhythm suggesting decreased ventricular compliance from myocardial inflammation and edema
• Innocent systolic flow murmurs may be accentuated
• Pansystolic murmur (mitral regurgitation) heard best between low left sternal border and apex in ~25% of patients
• Diastolic murmur (aortic regurgitation) is rare
• Small pericardial effusions are common on echocardiography, though pericardial rub is very rare

Electrocardiographic Changes 1

• Arrhythmias including sinus node and atrioventricular node dysfunction
• Prolonged PR interval
• Nonspecific ST and T-wave changes or low voltage with myocardial/pericardial involvement
• Rarely, malignant ventricular arrhythmias in the setting of myocarditis or myocardial ischemia

Cardiovascular Collapse 1

• Approximately 5% of children present with cardiovascular collapse and hypotension
• Often associated with thrombocytopenia and coagulopathy
• Frequently misdiagnosed as bacterial sepsis initially
• Higher risk of IVIG resistance, coronary artery abnormalities, mitral regurgitation, and prolonged myocardial dysfunction

Other Clinical Findings

Musculoskeletal 1

• Arthritis or arthralgia in approximately one-third of patients
• First week: Multiple joints including small interphalangeal joints and large weight-bearing joints
• After day 10: Predominantly large weight-bearing joints, especially knees and ankles

Neurological 1

• Extreme irritability exceeding that of other febrile illnesses
• Aseptic meningitis in ~30% who undergo lumbar puncture (mononuclear cell predominance, normal glucose, generally normal protein) 1
• Transient unilateral peripheral facial nerve palsy (rare) 1
• Transient high-frequency sensorineural hearing loss (20-35 dB), but persistent hearing loss is rare 1

Gastrointestinal 1

• Diarrhea, vomiting, and abdominal pain in approximately one-third of patients
• Hepatic enlargement and jaundice can occur
• Acute acalculous gallbladder hydrops in 15% during first 2 weeks (identifiable by ultrasound)
• Rarely presents as acute surgical abdomen

Genitourinary 1

• Sterile pyuria in up to 80% of children (lacks specificity) 1
• Urethritis is common 1
• Hydrocele and phimosis are less common 1

Other Findings 1

• Erythema and induration at BCG vaccination site (common in countries where BCG is used widely)
• Testicular swelling (rare)
• Pulmonary nodules and pleural effusions (rare)
• Peribronchial and interstitial infiltrates on chest radiography 1

Laboratory Findings

Acute Phase Reactants 1, 4

• Elevation of ESR and CRP is nearly universal
• Clinical pearl: KD is unlikely if ESR, CRP, and platelet count are normal after day 7 of illness 1, 4
• CRP normalizes more quickly than ESR during resolution 1, 4
• ESR is elevated by IVIG therapy, making it less useful for monitoring treatment response 1, 4
• Minimally elevated ESR with severe clinical disease should prompt investigation for disseminated intravascular coagulation 1, 4

Hematologic Findings 1, 4

• Leukocytosis: Typical during acute stage with predominance of immature and mature granulocytes; ~50% have WBC >15,000/mm³ 1, 4
• Leukopenia: Rare and suggests alternative diagnosis 1, 4
• Anemia: Normochromic and normocytic, resolves with inflammation resolution 1, 4
• Thrombocytosis: Characteristic but generally not until second week, peaking in third week (mean ~700,000/mm³), normalizing by 4-6 weeks 1, 4
• Thrombocytopenia: Rare but may occur in first 1-2 weeks; sign of disseminated intravascular coagulation and risk factor for coronary artery abnormalities 1, 4

Other Laboratory Abnormalities 1, 4

• Mild to moderate elevations in serum transaminases or gamma-glutamyl transpeptidase in 40-60% 1, 4
• Mild hyperbilirubinemia in ~10% 1, 4
• Hypoalbuminemia is common and associated with more severe and prolonged acute disease 1, 4
• Arthrocentesis in patients with arthritis: purulent-appearing fluid with WBC 125,000-300,000/mm³, normal glucose, negative Gram stain and cultures 1

Incomplete (Atypical) Kawasaki Disease

Consider incomplete Kawasaki disease in children with fever ≥5 days AND only 2-3 principal features, or infants with fever ≥7 days without explanation. 1, 2, 3

High-Risk Populations 2, 3

• Infants <6 months: May present with only prolonged fever and irritability, yet have the highest risk of coronary abnormalities
• Older children and adolescents: Often have delayed diagnosis and higher prevalence of coronary artery abnormalities

Evaluation Algorithm 1, 2, 3

• Check inflammatory markers (ESR, CRP)
• Assess supplemental laboratory criteria: anemia for age, platelet count ≥450,000/mm³ after day 7, albumin <3.0 g/dL, elevated ALT, WBC ≥15,000/mm³, urine ≥10 WBC/hpf 1, 4
• Obtain echocardiogram if criteria met
• Echocardiogram is positive if: Z score of LAD or RCA ≥2.5, coronary artery aneurysm observed, or ≥3 suggestive features (decreased LV function, mitral regurgitation, pericardial effusion, or Z scores 2-2.5) 1

Common Diagnostic Pitfalls

Misdiagnosis Scenarios 1

• Bacterial lymphadenitis: Children may present with only fever and unilateral enlarged cervical lymph node; rash and mucosal changes that follow are mistaken for antibiotic reaction 1
• Partially treated UTI: Sterile pyuria mistaken for partially treated urinary tract infection with sterile cultures 1, 4
• Viral meningitis: Young infant with fever, rash, and CSF pleocytosis 1, 4
• Acute surgical abdomen: Occasionally presents with acute abdominal symptoms 1

Key Considerations 1

• KD should be considered in every child with fever of at least several days' duration, rash, and nonpurulent conjunctivitis
• Especially important in children <1 year old and adolescents, where diagnosis is frequently missed

Treatment Implications

Early treatment with IVIG and aspirin within 10 days of fever onset significantly reduces coronary artery abnormality risk. 2, 3

• Fever typically resolves within 36 hours after IVIG completion 2
• Persistence of fever indicates IVIG resistance requiring further therapy 2
• Treatment should be given within 10 days of fever onset or after the tenth day in the presence of ongoing inflammation (elevated CRP, ESR) 1