What are the signs and symptoms of Kawasaki disease in children under 5?

Signs and Symptoms of Kawasaki Disease

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

Principal Clinical Features (Must Have ≥4 of 5)

1. Fever Characteristics

• High-spiking fever typically exceeding 39-40°C (102.2-104°F) with a remittent pattern 1, 2, 3
• Persists despite antibiotic and antipyretic treatment 3
• Without treatment, lasts an average of 11 days (range 1-3 weeks) 1, 4
• Diagnosis can be made with only 4 days of fever when ≥4 principal features are present, particularly with hand/foot swelling 2, 4
• Experienced clinicians may diagnose with 3 days of fever in rare classic presentations 2, 4

2. Bilateral Conjunctival Injection

• Non-purulent, primarily affecting the bulbar conjunctiva with limbal sparing 1, 3, 4
• Notably absent photophobia or eye pain 1, 3
• No exudate, conjunctival edema, or corneal ulceration 1
• Begins shortly after fever onset 1

3. Oral Mucosal Changes

• Erythema and cracking of lips with dryness, fissuring, peeling, and bleeding 1, 3, 4
• "Strawberry tongue" with erythema and prominent fungiform papillae (indistinguishable from streptococcal scarlet fever) 1, 3
• Diffuse erythema of oral and pharyngeal mucosa 1, 3, 4
• Oral ulcerations and pharyngeal exudates are NOT seen 1

4. Polymorphous Rash

• Most commonly diffuse maculopapular eruption, erythroderma, or erythema multiforme-like pattern 1, 3, 4
• Usually extensive with trunk and extremity involvement 1
• Accentuation in the perineal region where early desquamation may occur 1
• Bullous and vesicular eruptions have NOT been described 1

5. Extremity Changes

• Acute phase: Erythema and edema of hands and feet with sharp demarcation at wrists/ankles 1, 3, 4
• Convalescent phase (2-3 weeks later): Periungual desquamation of fingertips 1, 3, 4
• Transverse furrows of fingernails (Beau's lines) during convalescence 1

6. Cervical Lymphadenopathy

• Least common of the principal features 1, 3, 4
• Usually unilateral and confined to the anterior cervical triangle 1, 3, 4
• ≥1.5 cm in diameter 1, 3, 4
• Firm, nonfluctuant, not associated with marked erythema of overlying skin 1
• Nontender or only slightly tender 1

Cardiac Manifestations

• Hyperdynamic precordium, tachycardia, gallop rhythm 1
• Innocent flow murmur in setting of anemia, fever, and depressed myocardial contractility 1
• Pansystolic regurgitant murmur if significant mitral regurgitation present 1
• Rarely, low cardiac output syndrome or shock 1
• ECG changes: arrhythmias, prolonged PR interval, nonspecific ST-T wave changes 1

Other Significant Clinical Findings

Gastrointestinal

• Diarrhea, vomiting, abdominal pain (approximately one-third of patients) 1, 4
• Acute acalculous gallbladder hydrops (15% of patients in first 2 weeks) 1, 4
• Hepatic enlargement, jaundice, mild transaminase elevation 1
• Rarely presents as acute surgical abdomen 1

Musculoskeletal

• Arthritis or arthralgia in approximately one-third of patients 1, 2, 4
• First week: multiple joints including small interphalangeal and large weight-bearing joints 1
• After day 10: favors large weight-bearing joints (knees, ankles) 1

Neurological

• Striking irritability (more than other febrile illnesses) 1, 4
• Transient unilateral peripheral facial nerve palsy (rare) 1
• Mononuclear pleocytosis in cerebrospinal fluid 1
• Transient high-frequency sensorineural hearing loss (20-35 dB) 1

Genitourinary

• Sterile pyuria of urethral origin 1, 4
• Occasional proteinuria 1
• Testicular swelling (rare) 1

Respiratory

• Cough, rhinorrhea, pulmonary infiltrate 1

Supportive Laboratory Findings

• Elevated ESR and CRP (acute phase reactants) 1, 2, 3, 4
• Leukocytosis with neutrophil predominance and left shift 1, 4
• Thrombocytosis (common in second week after fever onset) 2, 4
• Hypoalbuminemia and hyponatremia 1, 4
• Mild anemia in acute phase 1
• Elevated liver enzymes 4

High-Risk Populations Requiring Heightened Suspicion

• Infants <6 months may present with only prolonged fever and irritability, yet have the highest risk of coronary abnormalities 2, 4, 5
• Older children and adolescents often have delayed diagnosis and higher prevalence of coronary artery abnormalities 2
• Children of Asian descent have significantly higher incidence (150 per 100,000 in Japanese children vs. 10-15 per 100,000 in United States) 1, 3

Incomplete (Atypical) Kawasaki Disease

• Consider in children with fever ≥5 days AND only 2-3 principal features, or infants with fever ≥7 days without explanation 2, 3, 4
• Coronary artery complications occur at least as frequently in incomplete cases as in classic cases 1, 3
• When suspected, immediately measure ESR and CRP, and consider CBC, comprehensive metabolic panel, urinalysis, and echocardiography 2, 3

Critical Diagnostic Pitfalls

• Clinical features are typically not all present simultaneously—careful review of prior signs and symptoms over the illness course is essential 3, 4
• Cervical lymphadenopathy as predominant initial finding can mimic bacterial lymphadenitis, significantly delaying diagnosis 3, 4
• Strawberry tongue and rash should not be attributed solely to antibiotic reaction 3
• Male-to-female ratio is 1.5:1 1
• 80% of cases occur in children under 5 years of age 1, 6