Pityriasis Versicolor

PITYRIASIS VERSICOLOR

Causative Organism

• Caused by yeast-like micro-organism Pityrosporum ovale (orbiculare) or Malessezia 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

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