What organism is most commonly responsible for tinea versicolor?

• A. Candida albicans
• B. Aspergillus fumigatus
• C. Malassezia species (formerly Pityrosporum)
• D. Trichophyton rubrum

Answer: (C)

Malassezia species, a lipophilic yeast that normally colonizes the skin, is the organism most commonly responsible for tinea versicolor. It overgrows in oily areas of the skin, especially in warm, humid conditions, and disrupts pigment production in the epidermis, leading to the characteristic hypo- and hyperpigmented patches. On skin scrapings with KOH, you may see short hyphae with budding yeast—often described as “spaghetti and meatballs.” This differs from other fungi: Candida albicans typically causes mucosal candidiasis; Aspergillus fumigatus causes aspergillosis; Trichophyton rubrum is a dermatophyte that causes classic tinea infections like ringworm or athlete’s foot. So Malassezia best fits tinea versicolor.