Tinea (pityriasis) versicolor

Tinea (pityriasis) versicolor is a common skin condition caused by an overgrowth of yeast on the skin. It primarily affects the outer layer of the skin, leading to patches that may be lighter or darker than the surrounding skin. These patches often appear on the trunk, neck, and upper arms and can sometimes be mildly itchy. The condition is related to a type of yeast called Malassezia, which normally lives on the skin but can multiply excessively under certain conditions. It mainly affects the skin’s pigmentation, causing cosmetic concerns rather than serious health problems. The condition is more noticeable in warm, humid climates and can recur over time.

Tinea (pityriasis) versicolor is a superficial fungal infection of the skin caused by the lipophilic yeast Malassezia species. It results from the yeast's overgrowth and subsequent interference with normal melanocyte function, leading to hypopigmented or hyperpigmented macules and patches with fine scaling. The condition primarily affects the stratum corneum of the epidermis and is most common in adolescents and young adults, especially in hot, humid environments. The yeast produces azelaic acid and other metabolites that inhibit tyrosinase, disrupting melanin synthesis and causing characteristic pigmentary changes. Clinically, it is significant due to its chronic, recurrent nature and its impact on skin appearance rather than systemic illness.