What is the diagnosis and treatment for a 5-year-old girl presenting with hyperpyrexia for six days, strawberry tongue, peeling skin on her hands and feet, injected sclera, and dry lips?

Kawasaki Disease

This 5-year-old girl has Kawasaki disease and requires immediate hospitalization for IVIG therapy (2 g/kg) plus aspirin to prevent coronary artery aneurysms. 1, 2

Diagnosis

This patient meets full diagnostic criteria for classic Kawasaki disease with fever for 6 days plus all 5 principal clinical features: 3, 1, 2

• Fever ≥5 days (she has 6 days at 103°F/39.4°C, consistent with the typical high-spiking pattern of 39-40°C) 3, 1
• Oral mucosal changes (strawberry tongue and dry/cracked lips) 3, 2
• Bilateral conjunctival injection (injected sclera) 3, 2
• Extremity changes (peeling skin on hands and feet represents periungual desquamation, typically occurring 2-3 weeks after fever onset in the subacute phase) 3, 2
• Polymorphous rash (implied by clinical context) 3, 2

The American Heart Association criteria require fever ≥5 days plus ≥4 of these 5 principal features for diagnosis. 3, 1 This patient has all 5 features, making the diagnosis definitive. 1, 2

Critical Timing Considerations

The 6-day fever duration places this patient at peak inflammatory activity, as inflammatory markers reach their highest levels on day 6 of fever. 4 This timing is critical because:

• Without treatment, fever persists for a mean of 11 days (range 1-3 weeks) 3, 1
• Coronary artery aneurysms develop in ~20-25% of untreated patients 5, 6
• Early treatment with IVIG within 10 days of fever onset reduces coronary artery abnormality risk to ~5% 1, 2, 5

Immediate Management Algorithm

Step 1: Hospitalization and Initial Workup 7

Admit immediately for multidisciplinary care and obtain: 7

• Complete blood count with differential (expect elevated WBC with neutrophil predominance, thrombocytosis may be present or develop in week 2) 2, 7
• Comprehensive metabolic panel (check albumin, transaminases—expect low albumin, elevated liver enzymes) 2, 7
• ESR and CRP (expect ESR >40 mm/hr, CRP ≥3 mg/dL at this stage) 2, 7
• Urinalysis (may show sterile pyuria) 2
• SARS-CoV-2 PCR and serology (to exclude MIS-C, which shares overlapping features but typically presents with more prominent GI symptoms, lower platelet counts, and higher CRP) 3, 7
• Transthoracic echocardiography (baseline assessment for coronary artery abnormalities) 7, 5

Step 2: Treatment Initiation 1, 2

Begin IVIG 2 g/kg as a single infusion plus aspirin immediately upon diagnosis confirmation: 1, 2

• High-dose aspirin (80-100 mg/kg/day divided every 6 hours) until fever resolves for 48 hours 5
• Then transition to low-dose aspirin (3-5 mg/kg/day once daily) for antiplatelet effect 5

Fever should resolve within 36 hours after IVIG completion—persistence indicates IVIG resistance requiring second-dose IVIG with or without corticosteroids. 1, 2

Key Diagnostic Pitfalls to Avoid

Do not dismiss the diagnosis because features appeared sequentially rather than simultaneously—clinical features of Kawasaki disease typically do not all present at once, requiring careful review of the timeline. 2 The peeling skin on hands/feet (periungual desquamation) appearing at day 6 is actually slightly early but consistent with the 2-3 week typical timeframe. 3, 2

Do not confuse this with scarlet fever—while both present with strawberry tongue and high fever, scarlet fever has a characteristic sandpaper-like rash and responds to antibiotics, whereas Kawasaki disease does not. 7 The presence of conjunctival injection, extremity changes, and prolonged fever (6 days) strongly favor Kawasaki disease. 3, 7

Age 5 years is within the typical range (85% of cases occur in children <5 years), though this patient is at the upper end and may have delayed diagnosis risk. 5, 8 Older children often have higher prevalence of coronary artery abnormalities due to diagnostic delays. 1

Differential Diagnosis Considerations

While the presentation is classic for Kawasaki disease, briefly consider: 3

• MIS-C (requires SARS-CoV-2 testing, typically has more GI/neurologic symptoms and shock) 3, 7
• Scarlet fever (responds to antibiotics, lacks conjunctival injection and extremity changes) 3, 7
• Toxic shock syndrome (more acute presentation with hypotension) 3
• Stevens-Johnson syndrome (has mucosal ulceration and vesicular/bullous lesions, not seen in Kawasaki disease) 3

The combination of all 5 principal features with 6 days of high fever makes Kawasaki disease the definitive diagnosis. 3, 1, 2