Tinea Incognito — SCE Dermatology MCQ

Instant feedback + full explanation. One question, done properly.

EasyCutaneous InfectionTinea IncognitoSCE Dermatology

A 45-year-old man presents with pruritic erythematous patches on his scrotum. He has been using topical Betamethasone valerate for what he believed was eczema. The rash worsened with steroid treatment. KOH preparation from scrotal skin reveals branching hyphae. What is the diagnosis?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: C — Tinea cruris extending to scrotal skin — modified by topical corticosteroid (tinea incognito)

The correct answer is C, tinea cruris extending to scrotal skin, modified by topical corticosteroid (tinea incognito). This man applied betamethasone valerate, a potent topical steroid, to a dermatophyte infection misdiagnosed as eczema. The steroid dampens the local immune response, so the rash loses its classic well-demarcated, annular, scaling edge and instead spreads, becomes less inflamed looking, and worsens despite treatment, the hallmark history of tinea incognito. Scrotal skin can become involved when groin tinea spreads inferiorly, and the positive KOH preparation showing branching hyphae confirms a dermatophyte rather than an eczematous or psoriatic process. Correct management is to stop the corticosteroid and start an appropriate antifungal (topical terbinafine or an imidazole for localised disease, oral terbinafine for extensive or scrotal involvement).

Reference: https://www.nice.org.uk/guidance/conditions-and-diseases/skin-conditions