Nasolabial Sores in a 4-Year-Old Child
The most likely diagnosis is impetigo, a superficial bacterial skin infection that commonly affects the face and extremities of young children, and first-line treatment is topical mupirocin or fusidic acid applied three times daily for 5-7 days. 1, 2
Most Likely Diagnosis: Impetigo
Impetigo is the most common bacterial skin infection in children aged 2-5 years, with nonbullous impetigo (70% of cases) characteristically presenting as honey-colored crusts on the face. 1 The nasolabial area (between mouth and nose) is a classic location for this infection. 1, 3
Key Clinical Features to Confirm:
- Honey-colored or golden crusted lesions that may have started as small vesicles or pustules 1
- Lesions that began as red macules progressing to vesicles, then rupturing to form the characteristic crusts 3
- No systemic symptoms (fever, significant pain) in uncomplicated cases 1
- Possible history of minor trauma, insect bites, or pre-existing skin conditions (eczema) that impetigo secondarily infected 1
First-Line Treatment
Topical antibiotic therapy is the preferred initial treatment for localized impetigo: 1, 2
- Mupirocin 2% ointment applied to affected areas three times daily for 5-7 days 1, 2
- Fusidic acid 2% cream (if available) applied three times daily as an alternative first-line option 1, 2
- Retapamulin 1% ointment applied twice daily for 5 days is another topical option 1
When to Use Oral Antibiotics:
Oral antibiotics are indicated when: 1
- Multiple lesions are present or widespread involvement exists 1
- Topical therapy is impractical due to extent of disease 1
- The child has large bullae (bullous impetigo) 1
Oral antibiotic options include: 1, 2
- First-line: Cephalexin 25-50 mg/kg/day divided into 3-4 doses 1
- Dicloxacillin or flucloxacillin for confirmed Staphylococcus aureus 1, 2
- Clindamycin if methicillin-resistant S. aureus (MRSA) is suspected 1
- Amoxicillin-clavulanate provides coverage for both S. aureus and Streptococcus pyogenes 1
Important: Penicillin alone is NOT effective for impetigo and should not be used. 1
Alternative Diagnoses to Consider
Herpes Simplex Virus (HSV)
If lesions appear as grouped vesicles on an erythematous base rather than honey-crusted sores, consider primary HSV infection: 4, 5
- HSV typically presents with painful vesicular lesions that progress to shallow ulcers 4
- Treatment requires oral acyclovir 20 mg/kg (maximum 400 mg) five times daily for 7-10 days in children under 12 years 4
- Topical antivirals alone are substantially less effective than oral therapy 6
Herpes Zoster (Shingles)
Extremely unlikely in a 4-year-old unless immunocompromised, but if vesicular lesions follow a dermatomal distribution: 7
- Requires immediate ophthalmology referral within 24 hours if periocular involvement is present 7
- Treatment is oral acyclovir 800 mg five times daily (adult dose; pediatric dosing requires adjustment) 7
Critical Pitfalls to Avoid
Do not confuse impetigo with viral infections: 1, 3
- Impetigo has honey-colored crusts, while HSV has grouped vesicles that become shallow ulcers 1, 4
- Impetigo is not typically painful, whereas HSV lesions are usually painful 4
Do not use topical corticosteroids if any vesicular viral infection is suspected, as steroids promote viral replication and worsen infection. 6, 7
Obtain bacterial culture if: 2
- The child does not respond to initial therapy within 3-5 days 1
- There is concern for antibiotic-resistant organisms (MRSA) 1
- Bullous impetigo or widespread disease is present 2
Screen household contacts: 2
- Obtain nasal swabs from the patient and immediate family members to identify asymptomatic S. aureus carriers 2
- Treat carriers with topical mupirocin to the nares twice daily for 5 days to prevent recurrence 2
Expected Clinical Course
Impetigo typically resolves within 2-3 weeks without scarring, and complications are rare. 1 The most serious potential complication is poststreptococcal glomerulonephritis, though this remains uncommon. 1
Reassess at 3-5 days: 1