Tinea versicolor - back
Tinea versicolor is caused by the organism Pityrosporum ovale. It occurs most often in young adults. Wood's lamp examination revelas pale yellow-green fluorescence. KOH prep reveals "spaghetti and meatballs" with hyphae and spores. Skin lesions are sharply marginated macules, either hyper or hypopigmented, covered with fine scale. Small discrete lesions may eventually coalesce to cover large areas of the trunk.