A patient presents with erythematous papules and macules on both hands and feet that began one week ago with fever, and now has right‑sided acute otitis media. What is the most likely diagnosis and appropriate management?

Kawasaki Disease is the Most Likely Diagnosis

This clinical presentation—erythematous papules and macules on bilateral hands and feet following fever one week ago, now with acute otitis media—is highly suggestive of Kawasaki disease, and immediate evaluation for coronary artery involvement with echocardiography and treatment with IVIG plus aspirin should be initiated urgently to prevent potentially fatal coronary artery aneurysms.

Clinical Reasoning for Kawasaki Disease

Key Diagnostic Features Present

• Extremity changes: Erythema of the palms and soles with firm induration of the hands or feet are distinctive acute phase findings in Kawasaki disease, typically appearing within the first 5 days of fever onset 1

• Fever timing: The patient had fever one week ago, which aligns with the typical Kawasaki disease presentation where fever persists for 1-3 weeks without treatment and clinical features evolve over time rather than appearing simultaneously 1

• Associated otitis media: Acute otitis media is a recognized associated finding in Kawasaki disease and does not exclude the diagnosis 1

Diagnostic Criteria Assessment

Classic Kawasaki disease requires ≥5 days of fever plus ≥4 of 5 principal clinical features 1:

1. Oral changes (erythema/cracking of lips, strawberry tongue)
2. Bilateral bulbar conjunctival injection without exudate
3. Rash (maculopapular, diffuse erythroderma, or erythema multiforme-like)
4. Extremity changes (erythema and edema of hands/feet) ✓ Present
5. Cervical lymphadenopathy (≥1.5 cm)

The patient currently has documented extremity changes and rash on hands/feet 1. A careful history must be obtained to determine if other principal features were present during the illness but resolved by presentation, as clinical features are typically not all present simultaneously 1.

Critical Differential Diagnoses to Exclude

Rocky Mountain Spotted Fever (RMSF) - Must Be Excluded Immediately

• RMSF is a life-threatening emergency where 50% of deaths occur within 9 days, and the rash typically appears 2-4 days after fever onset, beginning as small blanching pink macules on ankles, wrists, or forearms that evolve to maculopapules 1, 2

• However, RMSF rash involving palms and soles typically indicates advanced disease (day 5-6) and is associated with severe systemic illness including high fever, severe headache, and altered mental status 1, 2

• The patient's presentation one week after fever with current otitis media (not severe systemic toxicity) makes RMSF less likely, but if there is any history of tick exposure, severe headache, or systemic toxicity, empiric doxycycline must be started immediately 2

Hand, Foot, and Mouth Disease (HFMD)

• HFMD presents with vesicular lesions (not just erythematous papules/macules) concentrated on hands, feet, and mouth, with fever typically low-grade (<102.2°F) 3, 4

• The key distinguishing feature is that HFMD has discrete vesicles, whereas Kawasaki disease presents with diffuse erythema and edema 3, 4

• The timing (one week post-fever) and lack of vesicular description makes HFMD less likely 3

Erythema Multiforme

• Erythema multiforme presents with target-like lesions that are fixed for minimum 7 days, typically on extensor surfaces of extremities spreading centripetally 5, 6

• While erythema multiforme can involve hands and feet, it lacks the firm edema and induration characteristic of Kawasaki disease 5

• Erythema multiforme is typically preceded by HSV infection or medications, not associated with otitis media 5, 6

Immediate Management Algorithm

Step 1: Urgent Assessment for Kawasaki Disease

Examine for all 5 principal clinical features 1:

• Check for conjunctival injection (bilateral, bulbar, nonexudative)
• Examine oral mucosa for erythema, lip cracking, strawberry tongue
• Document rash characteristics and distribution
• Assess for cervical lymphadenopathy (≥1.5 cm, usually unilateral)
• Confirm extremity changes (erythema, edema, induration)

Obtain detailed history 1:

• Were other features present earlier but resolved?
• Duration of fever (count from first calendar day)
• Any recent tick exposure or travel to endemic areas?
• Medication history?

Step 2: Laboratory Evaluation

If Kawasaki disease is suspected 1:

• CBC with differential (expect normal/elevated WBC with neutrophil predominance)
• ESR and CRP (elevated acute phase reactants)
• Comprehensive metabolic panel (may show hyponatremia, elevated transaminases)
• Urinalysis (sterile pyuria may be present)
• Echocardiography to assess for coronary artery abnormalities (if present, confirms diagnosis)

If systemic toxicity or RMSF cannot be excluded 2:

• CBC with differential and peripheral smear
• Comprehensive metabolic panel
• Start empiric doxycycline immediately (even in children <8 years due to high RMSF mortality)

Step 3: Treatment Based on Diagnosis

For Kawasaki Disease 1:

• IVIG 2 g/kg as single infusion (primary treatment to prevent coronary artery aneurysms)
• High-dose aspirin 80-100 mg/kg/day divided every 6 hours until fever resolves for 48 hours
• Fever should resolve within 36 hours after IVIG completion; if not, patient has IVIG resistance requiring additional therapy
• After fever resolution, transition to low-dose aspirin (3-5 mg/kg/day) for antiplatelet effect

For Acute Otitis Media 7:

• Amoxicillin is first-line treatment for suppurative otitis media
• Duration: 8 days without perforation, 10 days with perforation
• Pain management with acetaminophen or ibuprofen

Critical Pitfalls to Avoid

Common Diagnostic Errors

• Do not wait for all 5 principal features to appear simultaneously - they evolve over time and some may have resolved by presentation 1

• Do not exclude Kawasaki disease if fever resolved spontaneously after 7 days - spontaneous resolution does not rule out the diagnosis 1

• Do not dismiss the diagnosis based on presence of otitis media - associated infections are common in Kawasaki disease 1

• Do not confuse the erythema multiforme-like rash of Kawasaki disease with true erythema multiforme - Kawasaki rash lacks the fixed target lesions and is associated with other diagnostic criteria 1

Life-Threatening Conditions Not to Miss

• RMSF requires immediate empiric doxycycline if there is any diagnostic uncertainty with systemic toxicity - waiting for confirmation can be fatal 2

• Meningococcemia can present similarly with rapidly progressive rash - if cannot be excluded, add ceftriaxone immediately 2

• Untreated Kawasaki disease carries 25% risk of coronary artery aneurysms, which can lead to myocardial infarction and sudden death 1

Treatment Timing Is Critical

• IVIG is most effective when given within 10 days of fever onset to prevent coronary artery complications 1

• Delay in Kawasaki disease treatment significantly increases risk of coronary artery aneurysms - do not wait for "complete" diagnostic criteria if clinical suspicion is high 1