If a patient has tinea corporis, what steps should be taken before initiating secukinumab (Scapho) therapy?

Treat and Clear Tinea Corporis Before Starting Secukinumab

Before initiating secukinumab (Scapho) in a patient with tinea corporis, you must first diagnose and completely treat the fungal infection, as IL-17 inhibitors significantly increase the risk of fungal infection exacerbation and can mask the clinical presentation.

Why This Matters

IL-17 plays a critical role in antifungal immunity, particularly against dermatophytes. Blocking IL-17A with secukinumab impairs the body's ability to control fungal infections. Recent case reports demonstrate that tinea corporis can develop or worsen during IL-17 inhibitor therapy and can clinically mimic a psoriasis flare, leading to diagnostic confusion and inappropriate treatment escalation 1, 2.

Step-by-Step Approach

1. Confirm the Diagnosis of Tinea Corporis

• Do not rely on clinical appearance alone - tinea corporis frequently mimics other conditions, especially in patients already using topical corticosteroids or calcineurin inhibitors 3, 4
• Obtain diagnostic confirmation:
  • Perform KOH (potassium hydroxide) preparation from skin scrapings taken from the active border of lesions - this provides immediate microscopic confirmation 3, 4, 5
  • Send fungal culture on Sabouraud's agar to identify the specific dermatophyte species, which guides treatment selection 5
  • Consider dermoscopy as a useful non-invasive adjunct 3

2. Treat the Tinea Corporis Completely

For localized tinea corporis:

• Use topical antifungals as first-line therapy 3, 4
• Continue treatment for the full course (typically 2-4 weeks) even after clinical improvement

For extensive, multiple, or treatment-resistant tinea corporis:

• Oral terbinafine is first-line for most dermatophytes, particularly Trichophyton species 6, 4
  • Adults: 250 mg once daily for 2-4 weeks
  • More effective than topical therapy for extensive disease 6
• Alternative: Itraconazole 100 mg once daily for 15 days (87% mycological cure rate) 6
• Griseofulvin is preferred for Microsporum species 7

3. Confirm Mycological Cure Before Starting Secukinumab

• Wait for complete clinical resolution AND negative repeat mycology (KOH and/or culture) before initiating secukinumab 7
• The endpoint is mycological cure, not just clinical improvement 7
• This typically requires 2-4 weeks after completing antifungal therapy

4. Screen for Other Fungal Infections

Before starting secukinumab, also evaluate for:

• Tinea pedis (athlete's foot) - common reservoir for reinfection
• Tinea unguium (onychomycosis) - requires longer treatment
• Tinea capitis if scalp involvement suspected

Critical Pitfalls to Avoid

Do not start secukinumab with active tinea corporis present - even if the fungal infection seems mild. IL-17 inhibition will impair fungal clearance and can lead to widespread, difficult-to-treat infection 1, 2.

Do not use combination antifungal-corticosteroid products - these are associated with treatment failure, mask the infection, and promote antifungal resistance 4, 8. Only 7-10% appropriate use has been documented, highlighting this as a major stewardship concern 8.

Do not assume clinical improvement equals cure - dermatophyte infections require mycological confirmation of clearance, as clinical appearance can be misleading, especially with concurrent immunosuppression 7, 3.

Special Considerations for Secukinumab

While the British Association of Dermatologists guidelines recommend exercising caution with IL-17 inhibitors in inflammatory bowel disease 9, the same vigilance applies to active fungal infections. The mechanism is clear: IL-17 is essential for mucocutaneous antifungal defense, and its inhibition creates a permissive environment for fungal proliferation 1, 2.

Monitoring After Starting Secukinumab

Once secukinumab is initiated after confirmed tinea clearance:

• Educate patients to report any new scaly, annular, or pruritic lesions immediately
• Maintain high clinical suspicion for tinea recurrence, as it may present atypically
• If suspected fungal infection develops, obtain KOH/culture before treating, as clinical diagnosis is unreliable in immunosuppressed patients 1, 2

The evidence is unequivocal: active tinea corporis must be completely eradicated with documented mycological cure before secukinumab initiation to prevent serious infectious complications and optimize biologic therapy outcomes 1, 2.