What is the diagnosis and management for a 9-year-old male with a 3-day history of a pruritic (itchy) skin lesion on his neck that has spread, with superficial abrasions, scabs, pus-filled areas, and bleeding, despite antifungal cream treatment, and now presents with feelings of warmth and chills?

Diagnosis: Impetigo with Secondary Bacterial Infection and Systemic Involvement

This is impetigo that has progressed to a more severe bacterial skin infection requiring immediate systemic antibiotic therapy, given the presence of fever, chills, and spreading lesions despite topical treatment. 1

Clinical Reasoning

The clinical presentation is classic for nonbullous impetigo that has worsened:

• Initial small pruritic papule that evolved into vesicles/pustules 1
• Characteristic honey-colored crusts and scabs from ruptured vesicles 1, 2
• Superficial abrasions with pus-filled areas and bleeding sites 1
• Spread from scratching (autoinoculation) 1
• Systemic symptoms (fever and chills) indicating deeper infection or bacteremia 1

The antifungal cream was ineffective because this is a bacterial infection, not fungal. 1 The most likely pathogens are Staphylococcus aureus and/or Streptococcus pyogenes (Group A Streptococcus). 1, 3

Key Differential Diagnoses to Consider

Ecthyma - This is a deeper form of impetigo with ulceration that occurs when impetigo is inadequately treated, which fits this progression. 2 The superficial bleeding sites and deeper involvement suggest evolution toward ecthyma. 2

Cellulitis - The spreading nature and systemic symptoms (fever, chills) raise concern for developing cellulitis, though the presence of crusts and pustules points more toward impetigo. 1 However, cellulitis can coexist with impetigo. 1

Atopic dermatitis with secondary bacterial infection - Less likely given the acute 3-day history without prior eczema history, but scratching can predispose to bacterial superinfection. 1, 4

Immediate Management Algorithm

1. Systemic Antibiotic Therapy (Required)

Given the systemic symptoms (fever, chills) and spreading infection, oral antibiotics are mandatory. 1, 2, 3

First-line options:

• Cephalexin (first-generation cephalosporin): 25-50 mg/kg/day divided into 3-4 doses for 7-10 days 1, 3
• Dicloxacillin: 12.5-25 mg/kg/day divided into 4 doses 1, 3
• Amoxicillin-clavulanate: 20-40 mg/kg/day (amoxicillin component) divided into 3 doses 1, 3

Avoid penicillin V as it is seldom effective for impetigo. 5

If MRSA is suspected (based on local resistance patterns or treatment failure): Consider clindamycin 10-20 mg/kg/day divided into 3 doses or trimethoprim-sulfamethoxazole. 1

2. Local Wound Care

• Debride all crusts using gentle cleansing with soap and water or poloxamer 188 2
• Apply topical mupirocin ointment three times daily to affected areas after crust removal 6, 5
• Cover with gauze dressing if desired 6
• This combination of systemic plus topical therapy is appropriate for extensive disease 1, 5

3. Hygiene Measures

• Keep fingernails trimmed short to prevent further autoinoculation from scratching 1
• Wash hands frequently and avoid touching the lesions 1
• Use separate towels and avoid sharing personal items 1
• Daily bathing with antibacterial soap 2

4. Monitor for Complications

Red flags requiring urgent evaluation:

• Worsening fever or systemic toxicity despite 48-72 hours of antibiotics 1
• Increasing pain disproportionate to clinical findings (suggests necrotizing infection) 1
• Woody-hard feel to subcutaneous tissues (necrotizing fasciitis) 1
• Development of bullae, skin necrosis, or ecchymoses 1
• Signs of cellulitis: spreading erythema, warmth, edema beyond the crusted areas 1

Post-streptococcal complications to monitor for:

• Acute glomerulonephritis (can occur 1-3 weeks after streptococcal impetigo) 1
• Check urinalysis if hematuria or edema develops 1

Clinical Pitfalls to Avoid

Do not rely on topical therapy alone when systemic symptoms are present - this patient needs oral antibiotics. 1, 2

Do not assume this is a fungal infection despite the initial presentation - the honey-colored crusts, pustules, and rapid spread are pathognomonic for bacterial impetigo, not dermatophyte infection. 1

Do not delay treatment - impetigo can progress to ecthyma, cellulitis, or rarely post-streptococcal glomerulonephritis if inadequately treated. 1, 2

Re-evaluate within 3-5 days - if no clinical improvement, consider culture and sensitivity testing, MRSA coverage, or alternative diagnoses. 6

Consider bacterial culture if the infection is severe, not responding to initial therapy, or if MRSA is suspected based on local epidemiology. 1