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Unmasking Tinea Incognito: Case Study, Insights Into the Pathogenesis, and Recommendations

Summary

A 29-year-old woman was incorrectly treated for psoriasis with steroids, which made her fungal infection worse instead of better. When doctors finally diagnosed her with a fungal infection (tinea incognito), they found it was caused by a common dermatophyte fungus. This case highlights how steroid creams can hide fungal infections and make them spread, and shows why recognizing this condition is important for proper treatment.

Background

Tinea incognito (TI) is a dermatophyte infection altered by inappropriate use of corticosteroids or immunosuppressive treatments, leading to atypical presentations that complicate diagnosis. The condition was initially described in 1968 and is frequently misdiagnosed as psoriasis, eczema, or other dermatological disorders due to lack of classic features.

Objective

To present a case of tinea incognito in a 29-year-old Maya female misdiagnosed with inverse psoriasis and explore the pathophysiological mechanisms of how corticosteroids mask clinical features and facilitate fungal dissemination.

Results

Patient had disseminated hyperpigmented erythematous-scaly plaques diagnosed as tinea corporis caused by Trichophyton mentagrophytes. Laboratory findings showed elevated HOMA-IR index (4.5) indicating insulin resistance. Treatment with oral itraconazole 100 mg daily for four weeks resulted in complete remission without complications.

Conclusion

Tinea incognito presents significant diagnostic challenges requiring integrated approach including patient history, mycological testing, and clinical examination. Chronic glucocorticoid use compromises immune response by diminishing IL-17 and IFN-γ cytokines, and TI occurrence should raise suspicion for underlying conditions such as obesity, insulin resistance, or diabetes.
  • Published in:Cureus,
  • Study Type:Case Report,
  • Source: PMID: 39569254, DOI: 10.7759/cureus.72042
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