Ptyriasis versicolor is caused by?
**Core Concept**
Pityriasis versicolor is a common skin condition characterized by hypopigmented or hyperpigmented macules, typically affecting the chest and back. It is caused by a yeast infection, specifically by a member of the Malassezia genus.
**Why the Correct Answer is Right**
The correct answer is a type of yeast that is naturally found on the skin and in the hair follicles. In individuals with oily skin, the Malassezia yeast can overgrow and cause an infection, leading to the symptoms of pityriasis versicolor. The yeast produces porphyrins, which are compounds that can stain the skin and cause the characteristic macular lesions.
**Why Each Wrong Option is Incorrect**
**Option A:** Trichophyton - This is a type of fungus that causes ringworm and other skin infections, but it is not associated with pityriasis versicolor.
**Option B:** Staphylococcus aureus - This is a type of bacteria that can cause skin infections, but it is not the causative agent of pityriasis versicolor.
**Option C:** Candida - This is a type of yeast that can cause various types of infections, but it is not associated with pityriasis versicolor.
**Clinical Pearl / High-Yield Fact**
Malassezia yeast can be found on the skin of healthy individuals, but it can overgrow and cause infection in individuals with oily skin or compromised immune systems.
**Correct Answer: C. Malassezia. Malassezia yeast.**