Diagnosis: Teaching File: Pityriasis Versicolor (KOH examination)
Superficial skin scrapings from pityriasis (tinea) versicolor demonstrating yeast and short mycelial forms.
Superficial skin scrapings from pityriasis (tinea) versicolor demonstrating yeast and short mycelial forms.
Submitted by Alaa Saad. Originally posted December 14, 2010.
See case discussion.
• Vitiligo • Pityriasis alba • Post-inflammatory hypopigmentation • Tinea corporis • Seborrheic dermatitis • Confluent and reticulated papillomatosis • Secondary syphilis
• Caused by Malassezia yeast (dimorphic: yeast → mycelial/hyphal form in disease state) • "Spaghetti and meatballs" on KOH: short hyphae with round spores — pathognomonic • Color varies: hypo- or hyperpigmented patches depending on skin tone and sun exposure • Hypopigmentation mechanism: azelaic acid produced by Malassezia inhibits tyrosinase • High recurrence rate — maintenance therapy recommended • Wood lamp: yellow-gold fluorescence • Not truly contagious — Malassezia is part of normal skin flora; overgrowth is the issue • Risk factors: heat, humidity, oily skin, immunosuppression
Tags: teaching, file, pityriasis, versicolor, koh, examination, alaa saad