Pityriasis Versicolor

PITYRIASIS VERSICOLOR
  • Causative Organism
  • Caused by yeast-like micro-organism Pityrosporum ovale (orbiculare) or Malassezia furfur
  • Becomes pathogenic when its growth is encouraged by increased sebum secretion or depressed immunity
  • Skin Lesion Morphology
  • Pale, scaling hypopigmented macules develop over the skin of the chest and back in young adults 
  • Fine velvety scales that are not visible but are seen by scraping the lesion.
  • Central upper trunk the most frequent site.
  • Microscopy: grape-like clusters of spores and a meshwork of pseudomycelium in skin scrapings
  • made more transparent by soaking the scales for 20 minutes in 20 per cent potassium hydroxide.
  • Skin surface biopsy
  • permanent preparation made using cyanoacrylate adhesive to remove a strip of superficial stratum corneum from the skin surface on a glass slide
  • The slide is 'rolled off' the skin after 20 seconds and then stained with periodic acid- Schiff reagent
  • The skin patches often fluoresce an apple green in long-wave UVR (Wood's light).
  • Treatment
  • Topical imidazole creams (e.g. miconazole, clotrimazole, econazole) for 6 weeks or
  • Ketoconazole shampoo to wash the affected areas once daily for 5 days
Exam Question
The skin patches often fluoresce an apple green in long-wave UVR (Wood's light).
Ketoconazole shampoo to wash the affected areas once daily for 5 days
Caused by yeast-like micro-organism Pityrosporum ovale (orbiculare) or Malassezia furfur

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