Superficial Mycoses

Overview
  • A variety of dimorphic fungal species cause "Superficial Mycoses" which are fungal infections that do not extend past the epidermis. Culprit fungi live within the stratum corneum of the skin and feed off of sloughing keratinocytes. Because tissues are not truly invaded, the immune response to these fungi is minimal. In general, the primary manifestation of superficial mycoses is discoloration of the skin and so they are of only cosmetic concern.
Pityriasis Versicolor
  • Etiology: Pityriasis Versicolor is caused by superficial infection with the dimorphic fungus "Malassezia furfur"
  • Clinical Consequences: The disease manifests as hyper- or hypo-pigmented macules of the skin
  • Detection: Skin lesions will fluoresce under Wood's Lamp and scrapings treated with potassium hydroxide (KOH) will reveal spaghetti and meatballs (hyphae and yeast forms, respectively).
Tinea Nigra
  • Etiology: Tinea Nigra is caused by superficial infection with the dimorphic fungus "Exophiala werneckii"
  • Clinical Consequences: The disease manifests as dark patches which often affect the palms and soles of the hands and feet
  • Detection: Skin scrapings will reveal pigmented hyphae and yeast forms.
Treatment
  • Selenium Sulfide found in dandruff shampoo can be spread over lesions.