A 45-year-old man presents with erythematous, greasy scales on the scalp, nasolabial folds, and presternal area. He is HIV-positive with a CD4 count of 85 cells/μL. Skin scrapings with 10% KOH show flask-shaped yeast forms with unipolar budding. What is the organism responsible and the first-line topical treatment?

• A Candida albicans; nystatin cream
• B Malassezia furfur; ketoconazole shampoo/cream ✓
• C Trichophyton rubrum; terbinafine cream
• D Pityrosporum ovale; selenium sulfide lotion

Explanation

Seborrhoeic dermatitis is caused by Malassezia furfur (also called Pityrosporum ovale in its yeast phase), which shows characteristic flask-shaped or bottle-shaped yeast cells with unipolar budding on KOH mount. It is markedly exacerbated in HIV infection and inversely correlates with CD4 count. First-line topical therapy is ketoconazole 2% shampoo or cream; selenium sulfide and zinc pyrithione shampoos are also effective alternatives. Option D incorrectly names the organism separately from its treatment.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.