Etiology and PathogenesisTop
1. Etiologic agent: Yeast-like fungi of the genus Malassezia, most commonly M furfur, normal inhabitants of the human skin, particularly on the scalp, neck, and shoulders.
2. Risk factors: Moist skin, increased sebum production, and immune system disorders. Pronounced lesions are observed in transplant recipients and persons with HIV infection.
CLINICAL FEATURES AND NATURAL HISTORYTop
Lesions are concentrated on the neck, shoulders, back, and chest. The eruptions appear as macules of different colors, initially pink, through yellowish brown, to brown (Figure 10.8-1). In summer, following sun exposure, well-demarcated white spots are visible at the site of infection (Figure 10.8-2). The depigmentation results from inhibition of melanin production by azelaic acid, a product of Malassezia. The eruptions are characterized by superficial flaking and presence of small scales. Recurrences are frequent.
Diagnosis is commonly based on clinical assessment and confirmed by direct mycologic examination (potassium hydroxide test [10% KOH]). Culture is not performed.
Seborrheic dermatitis, vitiligo, pityriasis rosea, pityriasis alba, syphilitic albinism.
1. Topical treatment is usually sufficient. Use antidandruff shampoos with azole derivatives (eg, ketoconazole, clotrimazole, econazole), Octopirox, selenium sulfide, or zinc pyrithione. The shampoo should be foamed and left on the skin for several minutes, then rinsed. Creams with azole derivatives are also effective. To avoid recurrences, periodic use of antifungal shampoos is indicated.
2. Use systemic treatment for extensive lesions. Options: oral fluconazole 50 mg once daily for 2 to 4 weeks or 300 mg once weekly for 2 weeks; oral itraconazole 200 mg once daily for 7 days or 100 mg once daily for 14 days.
Good personal hygiene.
Tinea versicolor. Numerous yellowish brown macules on the trunk.
Tinea versicolor. Numerous depigmented macules on the trunk, visible in summer following sun exposure.