Derm Cases · Dermatology / Infectious dermatology
OSCE — Malassezia disease: pityriasis versicolor vs Malassezia folliculitis
An 8-minute OSCE station on recognising Malassezia-related skin disease, distinguishing pityriasis versicolor from Malassezia folliculitis and acne, using KOH/Wood lamp, and selecting topical versus oral antifungal therapy — plus the neonatal lipid-infusion sepsis red flag.
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Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station on recognising Malassezia-related skin disease, distinguishing pityriasis versicolor from Malassezia folliculitis and acne, using KOH/Wood lamp, and selecting topical versus oral antifungal therapy — plus the neonatal lipid-infusion sepsis red flag.
Brief (to candidate)
A 24-year-old man who plays outdoor sport in humid weather has asymptomatic hypo- and hyperpigmented finely scaling macules across the upper trunk for 4 months. A second vignette card describes an itchy monomorphic follicular papulopustular eruption on the chest and back after a course of antibiotics for acne, with no comedones. You have 8 minutes to diagnose both Malassezia syndromes, confirm with bedside tests, and outline treatment and counselling.
[1]Candidate instructions
- Recognise pityriasis versicolor morphology and distribution.
- Distinguish Malassezia folliculitis from acne vulgaris.
- State KOH and Wood lamp findings.
- Give topical and oral antifungal regimens with duration.
- Name the neonatal lipid-infusion / central-line invasive disease red flag.
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Pityriasis versicolor | Finely scaling hypo/hyperpigmented macules on seborrhoeic trunk/shoulders; furfuraceous scale on scrape; cosmetic concern more than itch; recurrences common in heat/humidity[1][4] |
| Malassezia folliculitis | Itchy monomorphic follicular papules/pustules on trunk; no comedones; often after antibiotics, occlusion, or immunosuppression — not true acne[6] |
| Diagnostics | KOH: short hyphae + spores ('spaghetti and meatballs'); Wood lamp: pale yellow-gold fluorescence (versicolor); KOH/scrape or biopsy if folliculitis uncertain |
| Topical therapy | Ketoconazole 2% shampoo/cream, selenium sulfide 2.5%, or other imidazole; leave-on application to trunk; continue intermittent prophylaxis in high-risk seasons |
| Systemic therapy | Extensive PV: itraconazole 200 mg daily × 7 days or fluconazole 300 mg weekly × 2 (or equivalent short courses); oral antifungal for refractory folliculitis; avoid misusing long antibiotics for fungal folliculitis[1][4] |
| Counselling | Pigment change may lag weeks after mycologic cure; heat, humidity, oily skin, and immunosuppression favour relapse; seborrhoeic dermatitis overlap possible |
| Safety red flag | Neonate/infant on lipid-containing parenteral nutrition with central line and unexplained sepsis — consider invasive Malassezia; specialised culture media; remove catheter |
Model key actions
- Diagnose pityriasis versicolor with KOH/Wood lamp and treat with topical azole ± short oral azole for extensive disease.[1][4]
- Diagnose Malassezia folliculitis when monomorphic itchy follicular papules lack comedones; treat as fungus, not acne antibiotics.[6]
- Counsel recurrence risk and delayed pigment recovery; flag invasive disease in lipid-infused neonates.
Common errors
- Treating Malassezia folliculitis as acne with prolonged antibiotics.
- Missing KOH/'spaghetti and meatballs' confirmation.
- Promising immediate pigment normalisation after treatment.
- Using only facial acne topicals without trunk antifungal coverage for versicolor.
- Forgetting catheter/lipid-nutrition invasive Malassezia in neonates.
References3ShowHide
- [1]Saunte DML, Gaitanis G, Hay RJ. Malassezia-Associated Skin Diseases, the Use of Diagnostics and Treatment. Frontiers in cellular and infection microbiology, 2020.PMID 32266163
- [4]Leung AK, Barankin B, Lam JM, et al. Tinea versicolor: an updated review. Drugs in Context, 2022.PMID 36452877
- [6]Rubenstein RM, Malerich SA. Malassezia (pityrosporum) folliculitis. The Journal of clinical and aesthetic dermatology, 2014.PMID 24688625