OSCE — hypopigmented truncal scale: pityriasis versicolor diagnosis and antifungal therapy

Brief (to candidate)

A 24-year-old man notices coalescing pale, finely scaly patches on the upper chest and back after summer gym training. The patches do not tan with the surrounding skin. Itch is mild. You have 8 minutes to diagnose, confirm, treat, and counsel on recurrence and pigment return.

Candidate instructions

1. Recognise pityriasis versicolor (tinea versicolor) morphology and seborrhoeic distribution.
2. List key differentials for hypopigmented patches.
3. Use KOH / Wood lamp / dermoscopy concepts appropriately.
4. Prescribe topical ± oral antifungal correctly.
5. Counsel pigment lag and recurrence prevention.

Examiner checklist (mark each domain / 10)

Model key actions

• Diagnose PV from truncal branny hypo/hyperpigmented scale in a young adult.^[1]
• Confirm with KOH spaghetti-and-meatballs when needed; treat with topical azole/selenium ± oral azole if extensive.^[3][10]
• Counsel that pigment recovery lags mycological cure and recurrence is common.^[11]

Common errors

• Calling it vitiligo and starting unnecessary anxiety/work-up without noting scale.
• Using oral terbinafine as if dermatophyte tinea corporis.
• Declaring failure at 1 week because colour has not returned.

• Missing extensive disease that needs systemic therapy or confirmation.
• No recurrence prevention plan in sweaty tropical settings.