What is the diagnosis and management for a 9-year-old male presenting with a 3-day history of a pruritic (itchy) skin lesion on his neck that has spread to superficial abrasions with scabs, pus-filled areas, and superficial bleeding sites, unresponsive to antifungal creams?

Diagnosis: Impetigo with Systemic Involvement

This is impetigo—a highly contagious superficial bacterial skin infection—that has progressed beyond localized disease to include systemic symptoms, requiring immediate systemic antibiotic therapy. 1

Clinical Reasoning

The presentation is classic for nonbullous impetigo that has spread through autoinoculation from scratching:

• Initial small pruritic papule that evolved into vesicles/pustules 1
• Honey-colored crusts and scabs from ruptured vesicles with superficial abrasions, pus-filled areas, and bleeding sites 1
• Spread from scratching (autoinoculation) 1
• Systemic symptoms (fever, chills) indicating deeper infection or possible bacteremia 1
• Failure to respond to antifungal therapy (which was inappropriate) 1

The causative organisms are almost certainly Staphylococcus aureus and/or Streptococcus pyogenes (Group A Streptococcus). 2, 1

Key Differential Diagnoses

• Cellulitis: Possible given spreading nature and systemic symptoms, but the presence of crusts, pustules, and superficial nature points definitively toward impetigo 1
• Atopic dermatitis with secondary bacterial superinfection: Less likely as primary diagnosis, though scratching can predispose to bacterial infection 1
• Fungal infection: Ruled out by clinical appearance and failure to respond to antifungals 3, 4

Immediate Management

1. Systemic Antibiotic Therapy (Mandatory)

Given the systemic symptoms (fever, chills) and spreading infection, systemic antibiotics are absolutely required. 1

First-line oral antibiotic options: 1

• Cephalexin (preferred in most cases)
• Dicloxacillin
• Amoxicillin-clavulanate

If community-acquired MRSA (CA-MRSA) is suspected or the patient fails to respond to first-line therapy within 48-72 hours: 2, 1

• Clindamycin
• Trimethoprim-sulfamethoxazole

2. Local Wound Care

Debride all crusts and scabs to allow antibiotic penetration and reduce bacterial load. 1

Apply topical mupirocin ointment three times daily to affected areas after debridement. 1, 5 The FDA label specifies that mupirocin should be applied as a small amount to the affected area three times daily, with the area optionally covered with gauze dressing. 5

3. Hygiene Measures (Critical to Prevent Spread)

• Trim fingernails short to minimize trauma from scratching 1
• Wash hands frequently with soap and water 1
• Avoid touching or scratching lesions 1
• Use separate towels and linens; wash in hot water
• Keep child home from school until 24 hours after starting antibiotics (impetigo is highly contagious) 2, 1

Monitoring and Red Flags

Re-evaluate within 3-5 days if no clinical response 5

Urgent evaluation required if any of the following develop: 1

• Worsening fever or systemic toxicity
• Increasing pain (suggests deeper infection)
• Woody-hard feel to subcutaneous tissues (suggests necrotizing fasciitis)
• Development of bullae or skin necrosis
• Signs of spreading cellulitis (expanding erythema, warmth, induration)

Monitor for Post-Streptococcal Complications: 1

• Acute post-streptococcal glomerulonephritis can occur 1-3 weeks after streptococcal impetigo
• Watch for hematuria, edema, hypertension, or decreased urine output
• Consider urinalysis if any renal symptoms develop

Common Pitfalls to Avoid

Do not treat with antifungals—this is a bacterial infection, not fungal, despite the presence of crusts and scales. 1 The mother's use of antifungal cream was inappropriate and delayed proper treatment.

Do not rely on topical antibiotics alone when systemic symptoms are present. 2, 1 While topical mupirocin is effective for localized impetigo, systemic symptoms mandate oral antibiotics.

Do not underestimate the contagiousness—impetigo is one of the most common and contagious skin infections in children worldwide. 2