What is the role of microscopy in the diagnosis of pediatric tinea versicolor?

Updated: Jan 27, 2020
  • Author: Lyubomir A Dourmishev, MD, PhD; Chief Editor: Dirk M Elston, MD  more...
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Answer

Microscopic examination demonstrates the characteristic thick-walled spherical or oval yeast forms and coarse septate mycelium, often broken up into short filaments. This combination of mycelium strands and numerous spores is commonly referred to as "spaghetti and meatballs."

Liquid blue ink, methylene blue, or Swartz-Medrik stain can be added to the KOH preparation for better visualization of the causative organism.

Scales may also be removed using clear adhesive tape; they are then directly examined. The tape must be clear and is pressed several times over involved areas of skin. The tape is then lightly pressed, sticky side down, onto a microscope slide. A small drop of methylene blue or other appropriate stain is placed at the edge of the tape and allowed to run between the tape and the glass slide. Spores, often in grapelike clumps, and mycelium are easily seen. See the image below.

Clear adhesive tape can be pressed onto areas of t Clear adhesive tape can be pressed onto areas of tinea versicolor to collect hyphae and spores. The tape is then lightly pressed onto a glass slide, and a drop of methylene blue is placed at the edge of the tape. The methylene blue is allowed to run under the tape staining Malassezia furfur. The spores and hyphae easily are seen against a background clutter of keratinocytes and glue.

A few reports in literature have recently stated that 1% Chicago Sky Blue 6B (CSB) staining with 10% KOH is a new promising contrast diagnostic method for pityriasis versicolor, with 100% of sensitivity compared with 60.9% in culture. [7]


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