Tinea versicolor is caused by overgrowth of which organism?

• A. Candida albicans
• B. Trichophyton rubrum
• C. Pityrosporium obiculare
• D. Microsporum canis

Answer: (C)

Tinea versicolor results from overgrowth of a lipophilic yeast that normally lives on the skin. The organism responsible is Malassezia species, most often Malassezia furfur or Malassezia globosa. In older texts this yeast was called Pityrosporum ovale, which matches the name shown in the option. This organism thrives in warm, humid environments and interferes with melanin production in the skin, producing hypo- or hyperpigmented macules, usually on the trunk and proximal limbs. On skin scrapings treated with potassium hydroxide, you can see the characteristic yeast cells with short hyphae—often described as a spaghetti-and-meatballs appearance. It is not a dermatophyte and does not invade hair like Trichophyton rubrum or Microsporum canis, nor is it Candida albicans, which causes candidiasis.