Snapshot A 21-year-old man presents to his dermatologist for a rash on his face. He reports that there is no itch or pain associated with it. Although he spent a summer at the beach as a lifeguard and the rest of his face tanned, the area with the rash has not tanned, resulting in a white and yellow colored patches on his face. On physical exam, there are multiple yellow-white macules along his jawline and a large patch on his left cheek. There are also multiple similar patches on his trunk. A skin scraping and KOH preparation reveals tinea versicolor as a diagnosis. He is prescribed a medicated shampoo to use on his skin. Introduction Clinical definition very common cutaneous fungal infection characterized variably colored macules and patches also known as pityriasis versicolor Epidemiology prevalence 30-40% in tropical climates 1-4% in temperate climates demographics most common in adolescents and young adults risk factors hot and humid weather excessive sweating immunosuppression Etiology Malassezia spp. formerly Pityrosporum Pathogenesis when there is excessive heat and moisture, there may be increased growth of Malassezia spp. compared with other normal flora Associated conditions seborrheic dermatitis Prognosis often recurs Presentation Symptoms asymptomatic inability to tan in affected areas Physical exam macules and patches affecting the trunk, neck, and face lesions have overlying fine scaling variable color pale yellow white hypopigmentation hyperpigmentation yellowish brown Studies KOH preparation skin scrapings mixed with KOH short multibranching hyphae and budding cells “spaghetti and meatballs” appearance Wood lamp examination affected areas fluoresce yellow to yellow-green < 50% sensitivity Differential Vitiligo affected areas also fluoresce lesions are depigmented Eczema Psoriasis Seborrheic dermatitis Treatment Medical topical treatment indications avoid systemic effects of oral medications first-line therapy drugs zinc pyrithione 1% shampoo selenium sulfide 2.5% shampoo often also used for prophylaxis ketoconazole shampoo sulfur salicylic acid shampoo azole creams oral antifungals indication if disease is widespread or refractory to topical treatment drugs itraconazole fluconazole Complications Areas of discoloration may be permanent