What is the recommended management for a 5-month-old child with suspected herpetic whitlow and a rash that started on the neck and spread to the face and fingers, with symptoms including blisters, tactile fevers, and decreased oral intake?

Management of Suspected Herpetic Whitlow in a 5-Month-Old Infant

Direct Recommendation

This 5-month-old infant with classic herpetic whitlow (grouped vesicles on the finger from ungual region to PIP joint) and perioral HSV lesions should be treated with oral acyclovir immediately, given the 3-week duration, systemic symptoms (fevers, decreased oral intake), and young age placing her at higher risk for complications. 1, 2

Most Likely Etiology

Primary HSV-1 infection with herpetic whitlow and perioral involvement is the diagnosis based on:

• Grouped vesicles/bullae on the right 2nd finger (ungual region to PIP joint) - pathognomonic for herpetic whitlow 3, 4
• Perioral crusted ulcers on erythematous base - consistent with primary HSV gingivostomatitis 1
• Progressive spread pattern (neck → face → fingers over 3 weeks) 1
• Age-appropriate for primary HSV-1 infection (infants/young children) 1
• Autoinoculation mechanism: oral lesions leading to digital infection through direct contact 3, 4

Critical Differential Diagnoses to Exclude

Bacterial superinfection must be considered given:

• Duration of 3 weeks with ongoing progression 4
• Tactile fevers 4
• Initial misdiagnosis as "heat rash" delaying appropriate treatment 3

Eczema herpeticum should be excluded:

• Look for underlying atopic dermatitis with widespread vesicular eruption 1
• This is a dermatologic emergency with historically 10-50% mortality if untreated 1

Flexor tenosynovitis can mimic herpetic whitlow:

• Assess for Kanavel's cardinal signs (fusiform swelling, flexed posture, tenderness along flexor sheath, pain with passive extension) 5
• However, vesicular appearance strongly favors HSV 5

Diagnostic Approach

Immediate clinical diagnosis is sufficient to initiate treatment - do not delay therapy for confirmatory testing 1:

• Clinical presentation is classic and diagnostic 3, 4
• Peak viral titers occur in first 24 hours of lesion onset; this patient is already 3 weeks into illness 1

Consider confirmatory testing if available without delaying treatment:

• HSV PCR from vesicle fluid (most sensitive) 1, 4
• Viral culture from deroofed vesicles 3, 5
• Tzanck smear (rapid but less sensitive) 1

Laboratory confirmation is particularly important in this case because:

• Atypical duration (3 weeks) raises concern for immunodeficiency 1
• Young age (5 months) 1
• If bacterial cultures are obtained, they should not delay antiviral initiation 4

Treatment Recommendations

Immediate Antiviral Therapy

Oral acyclovir is the treatment of choice 1, 2, 5:

• Dosing: 20 mg/kg/dose orally 4-5 times daily for 7-10 days 2
• Maximum single dose: 400 mg 2
• Treatment should begin immediately despite 3-week duration 1, 5
• Acyclovir has documented safety in infants and children 2

Rationale for treatment despite delayed presentation:

• Ongoing viral replication evidenced by new vesicles continuing to appear 1
• Systemic symptoms (fever, decreased PO intake) indicate active infection 1
• Young age increases risk of severe disease 1
• Primary HSV infections are more severe and prolonged than recurrences 1, 6

Adjunctive Management

Discontinue topical hydrocortisone immediately 1:

• Corticosteroids can worsen HSV infection and increase risk of dissemination 1
• May have contributed to prolonged course and spread 1

Supportive care:

• Adequate hydration (especially important given decreased PO intake) 2
• Pain management with acetaminophen or ibuprofen (avoid aspirin in children) 1
• Gentle wound care without aggressive debridement 3, 4

Consider empiric antibiotics only if:

• Frank purulent drainage develops 1
• Bacterial culture grows pathogenic organism 1, 4
• Clinical signs of bacterial cellulitis worsen despite antiviral therapy 4

Monitoring and Follow-Up

Close follow-up within 48-72 hours to assess:

• Response to acyclovir (decreased new vesicle formation, improved oral intake) 2
• Resolution of fever 1
• No progression to eczema herpeticum or disseminated disease 1

Red flags requiring immediate re-evaluation:

• Worsening despite 48-72 hours of acyclovir (consider acyclovir resistance, though rare <0.5% in immunocompetent hosts) 7
• Development of widespread vesicular rash (eczema herpeticum) 1
• Signs of bacterial superinfection 1, 4
• Neurologic symptoms (altered mental status, seizures) 1

If treatment failure occurs:

• Consider IV acyclovir for severe or complicated disease 1, 2
• Evaluate for immunodeficiency (prolonged course in infant is concerning) 1, 7
• For confirmed acyclovir resistance: IV foscarnet 40 mg/kg three times daily 7

Critical Pitfalls to Avoid

Do not perform incision and drainage 3, 4, 5:

• Herpetic whitlow is frequently misdiagnosed as bacterial abscess or paronychia 3, 5
• Surgical intervention can worsen infection, cause bacterial superinfection, and prolong healing 4, 5
• The "minimal drainage" noted in case reports confirms this is a viral, not purulent, process 3, 4

Do not delay treatment waiting for confirmatory testing 1:

• Clinical diagnosis is sufficient 3, 4
• Early treatment is critical even though this patient presents late 1, 5

Do not use topical antivirals 1, 7:

• Topical acyclovir provides minimal benefit and cannot reach site of viral replication 1, 7
• Systemic therapy is required 1

Do not assume self-limited course will be benign 1:

• While HSV infections can be self-limiting in immunocompetent hosts, this infant has systemic symptoms and prolonged course 1
• Primary infections in young children can be severe 1
• Risk of autoinoculation to eyes or development of eczema herpeticum 1

Counseling for Family

Educate parents on:

• This is HSV-1 infection, likely acquired from contact with oral secretions (family member with cold sore, or asymptomatic shedding) 1, 3
• Infection will establish latency and may recur, though recurrences are typically milder 6
• Prevent autoinoculation: keep affected finger covered, prevent thumb/finger sucking until healed 3, 4
• Avoid contact with eyes 1
• Good hand hygiene for all family members 1
• Recurrences may be triggered by fever, stress, or UV exposure 1, 7