How is tinea corporis diagnosed and treated?

Diagnosis and Treatment of Tinea Corporis

Tinea corporis should be diagnosed through clinical examination and confirmed with potassium hydroxide (KOH) microscopy or culture, and treated with topical antifungals for localized infections or oral antifungals for extensive, resistant, or recurrent cases. 1

Diagnosis

Clinical Presentation

• Tinea corporis typically presents as well-demarcated, sharply circumscribed, oval or circular, mildly erythematous, scaly patches or plaques with a raised leading edge and mild pruritus 1
• The condition may mimic many other annular lesions, making laboratory confirmation important for accurate diagnosis 1

Diagnostic Methods

• Potassium hydroxide (KOH) microscopy of skin scrapings from the active border of the lesion is the primary diagnostic method 2, 1
  • Specimens should be collected using a blunt scalpel to remove skin scale 3
  • KOH preparation typically shows hyphae and/or arthroconidia 3
• Fungal culture on Sabouraud agar with cycloheximide is considered the gold standard for diagnosis 1, 4
  • Culture should be incubated for at least 2 weeks 3
  • Culture is particularly important when diagnosis is in doubt or infection is widespread, severe, or resistant to treatment 1
• Dermoscopy can be a useful non-invasive diagnostic tool to visualize characteristic features 1

Treatment

Topical Antifungal Therapy

• Topical antifungals are the standard first-line treatment for localized tinea corporis 1, 5
• Effective topical options include:
  • Azoles (e.g., clotrimazole 1%) - shown to be effective compared to placebo 6
  • Allylamines (e.g., terbinafine, naftifine) - terbinafine showed significantly higher clinical cure rates compared to placebo (RR 4.51,95% CI 3.10 to 6.56) 6
• Treatment duration:
  • Typically 2-4 weeks for tinea corporis 5
  • Treatment should continue for at least one week after clinical clearing of infection 5

Oral Antifungal Therapy

• Systemic antifungal treatment is indicated if the infection is: 1, 2
  • Multiple or extensive
  • Deep or chronic
  • Recurrent or unresponsive to topical treatment
  • Present in an immunocompromised patient
• Effective oral options include:
  • Itraconazole (100 mg daily) has shown superior efficacy (87% mycological cure rate) compared to griseofulvin (57% cure rate) when given for 15 days 3
  • Terbinafine appears superior for infections caused by Trichophyton tonsurans 3

Monitoring and Follow-up

• The definitive endpoint for treatment should be mycological cure, not just clinical response 2
• Follow-up with repeat mycology sampling is recommended until mycological clearance is documented 3
• Treatment failure may require extending treatment duration or switching to an alternative antifungal 2

Prevention

• Preventive measures include: 2, 4
  • Avoiding skin-to-skin contact with infected individuals
  • Not sharing towels, clothing, or other personal items
  • Covering lesions to prevent spread
  • Keeping affected areas clean and dry
  • Screening and treating family members if infection is caused by anthropophilic species 2

Common Pitfalls

• Misdiagnosis due to prior use of medications such as calcineurin inhibitors or corticosteroids that can alter the clinical appearance 1
• Stopping treatment too early based only on clinical improvement rather than mycological cure 2
• Not considering secondary bacterial infection in inflammatory cases 2
• Using combination antifungal/steroid agents inappropriately, which can cause atrophy and other steroid-associated complications 5