What could be causing a chronic rash resembling ringworm, with normal liver enzymes (alanine transaminase (ALT) and aspartate transaminase (AST)), that has not responded to triamcinolone acetonide, fluconazole (oral antifungal), and terbinafine (topical antifungal) cream?

Chronic Ringworm-Like Rash Unresponsive to Standard Antifungals

Most Likely Diagnosis

This is most likely NOT a dermatophyte infection, but rather granuloma annulare, nummular eczema, psoriasis, or another inflammatory dermatosis that mimics tinea corporis. The complete failure to respond to both oral fluconazole and topical terbinafine strongly suggests a non-fungal etiology, as these agents have high cure rates (42-66%) even in treatment-resistant dermatophytosis 1.

Why Standard Antifungals Failed

If This Were True Dermatophytosis:

• Terbinafine resistance is rare but emerging, with documented point mutations in the squalene epoxidase (SQLE) gene causing treatment failure 2
• Itraconazole is superior to both terbinafine and fluconazole for chronic/relapsing tinea, with 66% cure rates at 8 weeks versus 28% for terbinafine and 42% for fluconazole 1
• Microsporum canis infections specifically resist terbinafine and require doubled doses or alternative agents like itraconazole 3, 4

The Triamcinolone Problem:

• Using a topical corticosteroid on undiagnosed fungal infection causes "tinea incognito" - a modified clinical presentation that becomes chronic and treatment-resistant 1
• This may have masked the true diagnosis and altered the clinical appearance

Critical Next Steps

1. Confirm or Exclude Fungal Infection:

• Obtain KOH preparation AND fungal culture before any further treatment - culture is mandatory as it identifies the specific organism and allows resistance testing 5
• If culture is negative after proper sampling, this is NOT a fungal infection 5
• Consider fungal PCR if available, as it detected organisms when culture was positive 2

2. If Culture Confirms Dermatophyte:

• Switch to oral itraconazole 200 mg daily for minimum 4 weeks (not pulse dosing for resistant cases) 5, 1
• Itraconazole has broader coverage against non-dermatophyte molds and Candida species that may be misidentified as "ringworm" 5
• Request antifungal susceptibility testing and SQLE gene sequencing if itraconazole fails, as terbinafine-resistant strains require prolonged therapy 2
• For confirmed resistant cases, consider SUBA-itraconazole (super bioavailability formulation) 50 mg 5 days/week long-term 2

3. If Culture is Negative (Most Likely Scenario):

Consider these alternative diagnoses:

• Granuloma annulare: Annular plaques with raised borders, no scale, biopsy shows palisading granulomas
• Nummular eczema: Coin-shaped plaques, intensely pruritic, responds to topical corticosteroids (not just triamcinolone)
• Psoriasis: Silvery scale, extensor surfaces, nail changes
• Subacute cutaneous lupus: Photodistributed, check ANA and anti-Ro/La antibodies
• Contact dermatitis: Pattern matches exposure, patch testing may help

Treatment Algorithm for Confirmed Resistant Dermatophytosis

1. First-line: Oral itraconazole 200 mg daily for 8-12 weeks 1
2. If itraconazole fails: Request resistance testing 2
3. For confirmed resistance: SUBA-itraconazole 50 mg 5 days/week indefinitely 2
4. Adjunctive topical: Ciclopirox or miconazole cream (not terbinafine if resistant) 2
5. Monitor: Liver function tests at baseline and monthly during prolonged therapy 5

Critical Pitfalls to Avoid

• Never continue empiric antifungal therapy without culture confirmation - this delays correct diagnosis and wastes months of ineffective treatment 5
• Do not use topical corticosteroids on suspected fungal infections - this creates tinea incognito 1
• Normal ALT/AST does not exclude other diagnoses - these are only relevant for monitoring antifungal hepatotoxicity 5
• Up to 40% treatment failure occurs even with appropriate antifungals in the current epidemic of altered dermatophytosis, suggesting other factors beyond simple fungal infection 1

Bottom Line

Stop all current treatments, obtain proper fungal culture, and if negative, pursue alternative diagnoses with dermatology referral and possible skin biopsy. The combination of complete treatment failure with multiple appropriate antifungals and normal liver enzymes strongly suggests this is not a fungal infection 1.