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Tinea (pityriasis) versicolor, caused by lipophilic yeasts of the genus Malassezia, is the most common superficial skin infection. The clinical presentation usually consists of scaly hypo- or hyperpigmented macular lesions on the chest, back, neck, and arms.
Malassezia species are components of the human cutaneous flora that are dimorphic, existing in both yeast and mycelial phases. Each phase was originally classified as a separate genus: Pityrosporum for the yeast form and Malassezia for the mycelial form. The two genera were reclassified in 1986 as a single genus, Malassezia. Initially, only one species, M. furfur, was recognized, but seven distinct species have since been identified: M. furfur, M. sympodialis, M. obtusa, M. globosa, M. restricta, M. slooffiae, and M. pachydermatis.
Malassezia species can be isolated from sebaceous-rich areas of the skin, most frequently from the chest and the midline of the back. The prevalence of tinea versicolor in susceptible age groups (primarily adolescents and young adults) is low in temperate climates but may reach 40–60% in tropical climates.
The pathogenesis of tinea versicolor is unclear but may involve the conversion of colonizing yeasts into the mycelial form, which then invades the stratum corneum.
The lesions of tinea versicolor are usually asymptomatic. Most patients seek medical advice for cosmetic reasons. Lesions typically appear as patches of pink or coppery-brown skin but may appear paler than the surrounding skin, especially in dark-skinned individuals. Although some patients report mild pruritus, the lesions do not usually elicit an immune response. Other cutaneous manifestations associated with Malassezia species include seborrheic dermatitis, folliculitis, atopic dermatitis, and dandruff.
Tinea versicolor is diagnosed on clinical grounds by the characteristic distribution and appearance of skin lesions. Lesions may fluoresce yellow-green under long-wave UVA (Wood’s light). Treatment of skin scrapings with potassium hydroxide (KOH) reveals yeasts and hyphal elements with a “spaghetti and meatballs” appearance
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