What is the likely cause and treatment for itchy palms and soles of feet in a 6-year-old boy?

Itchy Palms and Soles in a 6-Year-Old Boy

Most Likely Diagnosis and Immediate Action

The most likely diagnosis is scabies, and you should treat immediately with permethrin 5% cream applied from head to toe (including scalp, palms, and soles), left on for 8-14 hours, with concurrent treatment of all household contacts. 1, 2

Diagnostic Approach

Primary Differential Diagnoses

The key conditions to distinguish are:

• Scabies: Intensely pruritic eruption with palmar and plantar involvement is characteristic in young children, unlike adults where these areas are typically spared 2, 3
• Atopic dermatitis: While common in children, it characteristically spares the palms and soles, making this less likely 4, 5
• Kawasaki disease: Consider if accompanied by 5+ days of high fever (≥39°C), conjunctival injection, oral changes, rash, or lymphadenopathy 4

Critical Red Flags Requiring Urgent Evaluation

Look for these features that change management urgently:

• Fever ≥5 days with any other systemic features → evaluate for Kawasaki disease immediately 4
• Grouped "punched-out" erosions or vesicles → suspect eczema herpeticum, requiring immediate systemic acyclovir 6, 7
• Extensive crusting, weeping, or honey-colored discharge → bacterial superinfection requiring flucloxacillin 6

Specific Diagnostic Features to Examine

For Scabies (Most Likely)

• Distribution: Papules, vesiculopustules, or nodules on palms, soles, face, and scalp are typical in young children 2
• Burrows: Difficult to find but diagnostic if present in interdigital web spaces 2
• Confirmation: Perform mineral oil scraping to visualize mites 2
• Family history: Ask about pruritus in other household members or caregivers 2

For Atopic Dermatitis (Less Likely Given Palm/Sole Involvement)

• Distribution: Should affect flexural areas (antecubital/popliteal fossae), cheeks in young children, but spares palms and soles 4, 5
• Chronicity: History of dry skin, personal or family atopy, onset in first 2 years 4
• Mandatory criterion: Pruritus must be present 5

For Kawasaki Disease (If Febrile)

• Fever pattern: High spiking (≥39°C) for ≥5 days 4
• Palm/sole findings: Erythema with firm, painful induration in acute phase; periungual desquamation occurs 2-3 weeks later 4
• Other features: Bilateral conjunctival injection, oral changes (cracked lips, strawberry tongue), polymorphous rash, cervical lymphadenopathy 4

Treatment Algorithm

First-Line Treatment for Scabies

Permethrin 5% cream is the treatment of choice 1, 2:

• Apply thoroughly from head to soles, including scalp, hairline, neck, temple, and forehead in children 1
• Leave on for 8-14 hours, then wash off 1
• Typical dose: 30 grams for average adult; adjust for child's size 1
• One application is generally curative 1
• Treat all household members and caregivers simultaneously 2
• Cleanse all articles of contact (bedding, clothing) 2

Post-Treatment Expectations and Pitfalls

• Persistent pruritus after treatment is normal and rarely indicates treatment failure; do not retreat unless living mites are demonstrated after 14 days 1
• Post-scabietic nodules may persist for months after mite clearance 2
• Secondary eczematization and impetiginization are common complications 2

If Atopic Dermatitis is Confirmed Instead

• Liberal emollients (≥2 times daily) to all affected areas 6
• Low-to-moderate potency topical corticosteroids (avoid high potency on face) 6, 8
• Avoid irritants (wool clothing, harsh soaps, temperature extremes) 4
• Keep nails short to minimize scratch damage 6

If Kawasaki Disease is Suspected

• Immediate referral for echocardiography and consideration of IVIG plus aspirin therapy 4
• Do not delay if fever ≥5 days with ≥4 principal criteria, or ≥4 days with 4 criteria 4

Common Pitfalls to Avoid

• Do not dismiss palmar/plantar involvement as "not scabies" in children – this distribution is characteristic in infants and young children, unlike adults 2, 3
• Do not retreat for persistent itching alone – pruritus commonly persists after successful scabies treatment and does not indicate failure 1
• Do not forget to treat household contacts – failure to treat all contacts simultaneously leads to reinfestation 2
• Do not overlook Kawasaki disease if any fever is present – ask specifically about fever duration and associated symptoms 4