What is the best treatment for a 12-year-old patient with tinea corporis (ringworm) that started on the ankle and has spread to other areas of the body?

Treatment of Widespread Tinea Corporis in a 12-Year-Old

For this 12-year-old with widespread tinea corporis that has disseminated from the ankle to multiple body sites, oral terbinafine is the treatment of choice given the extensive nature of the infection. 1, 2

Why Oral Therapy is Indicated

• Extensive disease involving multiple body sites requires systemic treatment rather than topical therapy 1, 2
• Topical antifungals are reserved for localized, limited tinea corporis, not widespread disseminated infection 2, 3
• The progression from a single ankle lesion to body-wide involvement indicates aggressive infection requiring systemic approach 1

Recommended Treatment Regimen

First-Line: Oral Terbinafine

• Dosing for this 12-year-old patient:
  • If weight <20 kg: 62.5 mg daily 4
  • If weight 20-40 kg: 125 mg daily 4
  • If weight >40 kg: 250 mg daily 4
• Duration: 2-4 weeks for tinea corporis 5, 2
• Advantages: Well-tolerated, effective, inexpensive, and fungicidal against T. rubrum and T. mentagrophytes (the most common causative organisms) 4, 1

Alternative: Oral Griseofulvin

• Dosing: 10 mg/kg daily (typically 250-500 mg daily for children >50 lbs) 5
• Duration: 2-4 weeks for tinea corporis 5
• Note: Less preferred than terbinafine but acceptable alternative 1

Alternative: Oral Fluconazole

• Dosing: 150 mg once weekly for 2-4 weeks 6
• Evidence: Effective for tinea corporis with significant reduction in symptom severity scores (from 7.1 to 1.5, p=0.001) 6
• Consideration: May be useful if terbinafine is not tolerated 7

Adjunctive Topical Therapy

• Add topical terbinafine 1% cream once daily to affected areas during oral treatment 8, 2
• This combination approach addresses surface infection while systemic therapy eradicates deeper follicular involvement 2
• For children 12 years and older, apply once daily for ringworm for 1 week 8

Critical Diagnostic Confirmation

Before initiating treatment, confirm the diagnosis:

• KOH preparation from active border of lesions is essential 2
• Fungal culture should be obtained given the extensive nature and to guide therapy if first-line treatment fails 2
• Clinical diagnosis alone is unreliable—tinea corporis can mimic eczema, psoriasis, and other conditions 1, 2

Important Management Pitfalls to Avoid

Do NOT Use Combination Antifungal-Steroid Creams

• While combination products show higher short-term clinical cure rates, they are not recommended in clinical guidelines due to concerns about steroid-related complications and antifungal resistance 1, 3
• The apparent benefit is temporary and does not improve mycological cure 3

Screen for Concurrent Infections

• Examine for tinea pedis (athlete's foot) as the original ankle lesion suggests this may be the source 4
• Check family members for tinea infections—household transmission is common and can lead to treatment failure 4
• Look for tinea capitis (scalp involvement) which would require different treatment duration 9

Hygiene and Prevention Measures

• Daily clothing changes and laundering of contaminated items 9
• Avoid sharing personal items (towels, clothing, sports equipment) 1
• Keep skin clean and dry—moisture promotes fungal growth 4

Monitoring and Follow-Up

• Clinical assessment at 2-4 weeks to evaluate response 2
• Repeat KOH/culture if no improvement to rule out resistant organisms or alternative diagnosis 2
• Continue treatment until complete clinical and mycological cure—premature discontinuation leads to relapse 5, 2

When to Suspect Treatment-Resistant Infection

• Emerging resistant tinea infections are increasingly reported and may not respond to standard first-line therapy 1
• If no improvement after 4 weeks of appropriate oral therapy, consider:
  • Prolonged oral antifungal therapy 1
  • Specialized diagnostic testing for resistant organisms 1
  • Referral to dermatology 1

Safety Considerations for Terbinafine

• Generally well-tolerated in children 4, 1
• Rare serious adverse events include neutropenia and liver failure (typically in those with preexisting liver disease) 4
• Baseline liver function tests are not routinely required for short courses (2-4 weeks) in healthy children 1