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Malassezia

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Summary

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Key Points

  • Malassezia
    • Includes M. globosa and M. furfur
    • Characteristics
      • Dimorphic fungus
      • Saprophytic, lipid-dependent
      • Not a dermatophyte
    • Transmission
      • Common in hot/humid climates
        • More common in summer and in tropical climates
    • Presentation
      • tinea versicolor (pityriasis versicolor)
        • Variably-colored macules and patches affecting the upper body (mb)
          • May be hypopigmented, hyperpigmented, or erythematous (hence: various color = versicolor)
          • Degradation of lipids by fungus inhibits tyrosinase involved in melanin production and inflammatory response to fungus causes redness
          • Affects trunk, neck, and face
          • Most visible after sun exposure or tanning of adjacent skin
        • Infection confined to stratum corneum of skin
    • Diagnosis
      • KOH preparation of skin scrapings (mb)
        • “Spaghetti and meatballs” appearance under light microscopy
          • Forms both spores and hyphae → hence spaghetti and meatballs
          • Hyphae with a “cigar-butt” appearance
      • Wood’s lamp examination (low-sensitivity)
        • Affected areas fluoresce yellow/green
    • Treatment
      • Responds well to medical therapy, but recurrence is common
      • Selenium sulfide shampoo
      • Itraconazole or Fluconazole may be used for refractory disease