A child presents with a perioral and arm rash and a strawberry (straw‑colored, enlarged) tongue; what is the most likely diagnosis and recommended immediate management?

Kawasaki Disease: Diagnosis and Immediate Management

This child most likely has Kawasaki disease, and you must initiate intravenous immunoglobulin (IVIG) 2 g/kg as a single infusion plus high-dose aspirin (80–100 mg/kg/day divided into four doses) immediately to prevent coronary artery aneurysms. 1, 2

Diagnostic Reasoning

The combination of strawberry tongue, perioral rash, and arm rash in a febrile child strongly suggests Kawasaki disease. 3 The American Heart Association defines classic Kawasaki disease as fever ≥5 days plus ≥4 of 5 principal features: bilateral non-purulent conjunctival injection, oral changes (strawberry tongue, cracked lips), polymorphous rash, extremity changes (erythema/edema), and cervical lymphadenopathy ≥1.5 cm. 1, 2

Key Clinical Features Present:

• Strawberry tongue (red, swollen tongue with prominent papillae) is one of the oral mucosal changes characteristic of Kawasaki disease 1, 2
• Polymorphous rash on arms and perioral area fulfills the rash criterion 1, 2
• These features, combined with fever, warrant immediate evaluation for Kawasaki disease even if other criteria are not yet apparent 1

Critical Diagnostic Pitfall:

Clinical features in Kawasaki disease appear sequentially, not simultaneously—you cannot wait for all 5 features to develop before treating. 2 If this child has had fever for ≥5 days with only 2–3 principal features, this represents incomplete Kawasaki disease, which carries the same risk of coronary complications as classic disease. 1, 2

Immediate Diagnostic Workup

Obtain these tests immediately while preparing for treatment: 1, 2

Laboratory Evaluation:

• ESR and CRP to document inflammation (ESR typically ≥40 mm/hr, often >100 mm/hr; CRP ≥3 mg/dL) 2
• Complete blood count (expect leukocytosis >15,000 cells/µL, neutrophilia, age-appropriate anemia, thrombocytosis after day 7) 2
• Comprehensive metabolic panel (look for hypoalbuminemia ≤3.0 g/dL, elevated ALT) 2
• Urinalysis (sterile pyuria >10 WBC/hpf is characteristic—do not mistake this for urinary tract infection) 2
• SARS-CoV-2 PCR and serology to rule out MIS-C (Multisystem Inflammatory Syndrome in Children), which has overlapping features 1

Cardiac Imaging:

Urgent transthoracic echocardiogram is mandatory to assess for coronary artery involvement (z-score ≥2.5 for left anterior descending or right coronary artery indicates abnormality). 2 Early vasculitis signs include perivascular brightness, lack of tapering, and coronary ectasia. 2

Differential Diagnosis Considerations

Scarlet Fever:

Scarlet fever also presents with strawberry tongue, fever, and sandpaper-like rash, most common in children aged 5–15 years. 1, 4 Key distinguishing features:

• Scarlet fever typically has pharyngeal exudate and responds to antibiotics 4
• Kawasaki disease has diffuse oral/pharyngeal erythema WITHOUT exudates or ulcers 2
• Obtain rapid strep test and throat culture to differentiate 4

MIS-C:

MIS-C presents with overlapping features but typically has more prominent GI symptoms, lower platelet counts, and higher CRP levels than classic Kawasaki disease. 1 Both conditions can cause coronary artery aneurysms and require similar urgent treatment. 1

Immediate Treatment Protocol

Treatment must be initiated within 10 days of fever onset to reduce coronary artery aneurysm risk from ~25% to ~5%. 2, 5, 6

First-Line Therapy:

• IVIG 2 g/kg as a single infusion 2, 6
• High-dose aspirin 80–100 mg/kg/day divided into four doses 2
• High clinical suspicion justifies starting IVIG and aspirin before completing the full echocardiographic evaluation 2

If No Response to Initial IVIG:

If fever persists 36 hours after completing the first IVIG infusion, administer a second dose of IVIG 2 g/kg with or without corticosteroids. 5, 6

Special Populations at Highest Risk:

• Infants <6 months with fever ≥7 days require echocardiography even with minimal clinical features due to highest risk of coronary abnormalities 2
• Children with early coronary artery dilatation or extreme laboratory abnormalities should receive corticosteroids in addition to IVIG 7

Critical Management Pitfalls to Avoid

Do not dismiss incomplete Kawasaki disease in infants <1 year—this age group has the highest risk of coronary abnormalities and often presents with fewer than 4 principal features. 1, 2

Do not attribute rash to antibiotic reaction if the child was initially treated for presumed bacterial infection—this is a classic missed diagnosis scenario for Kawasaki disease. 1

Do not wait for conjunctivitis to appear—incomplete Kawasaki disease is more common in infants and can present without bilateral conjunctival injection. 1

Sterile pyuria should never be dismissed as a partially treated urinary tract infection—it is a characteristic finding in Kawasaki disease. 2

Hospital Admission Required

This child requires immediate hospitalization for multidisciplinary team involvement, serial cardiac monitoring, and IVIG therapy administration. 1 Coronary artery aneurysm is a lethal complication of Kawasaki disease and represents the leading cause of acquired heart disease in children. 3, 5