Risk factors:
(1) infants, adolescent and the elderly
(2) hot environment with high humidity, such as the tropics
(3) oily skin (hyperhidrosis, liberal use of oil on the skin, other)
(4) prolonged use of an occlusive skin covering
Clinical features:
(1) scaling patches of skin that may be hypopigmented or hyperpigmented compared to adjacent skin
(2) chronic and asymptomatic
(3) do not tan following exposure to sunlight
(4) variable fluorescence under a Wood's lamp
(5) clearance after use of ketoconazole, selenium or "medicated" (sulfur and salicyclice acid) shampoo
Laboratory features:
(1) yeast and hyphae in skin scrapings from affected skin
(2) positive fungal cultures on media supplemented with olive oil or long-chain fatty acid
Diagnosis requires exclusion of other causes of dermatitis such as Candida.
