For several months, a 19-year-old manhad asymptomatic hyperpigmentedand hypopigmented macules on theright volar forearm. Recent applicationsof topical corticosteroids madethe lesions more noticeable.
For several months, a 19-year-old manhad asymptomatic hyperpigmentedand hypopigmented macules on theright volar forearm. Recent applicationsof topical corticosteroids madethe lesions more noticeable.Many of the round patches featuredfine scales. Examination of apotassium hydroxide (KOH) preparationof material from a scaly lesionrevealed the typical "spaghetti andmeatballs" appearance of hyphae andbudding yeast indicative of tineaversicolor.This infection is caused byMalassezia furfur, a lipophilic commensalyeast that is part of the normalflora in the keratin layer of all humans.Overgrowth, which leads tovisible lesions, is more likely in humidenvironments, in susceptible personswho use topical corticosteroids,and in those who produce excessivesebum. The incidence of tinea versicoloris higher in regions close to theequator.The single site of eruption withno signs of involvement elsewhere onthis patient was atypical. However,the characteristic KOH findings ruledout other conditions in the differentialdiagnosis, such as pityriasis alba, vitiligo,tinea corporis, nummular eczema,seborrheic dermatitis, and guttatepsoriasis. For example, the hyphaeseen on a KOH preparation ofscrapings from tinea corporis are typicallymuch longer, more discrete,and more filamentous than the short,clumped hyphae of tinea versicolor.(Case and photograph courtesy of Joe Monroe, PA-C.)