• Suspected fungal or candidal infection.

• Glass microscope slide and coverslip.

• 10–20% potassium hydroxide (KOH).

• Microscope.

• #15 scalpel blade or other device to scrape skin (edge of microscope slide, cytobrush, or foman blade).

• Matches.

• Minimal discomfort and bleeding with aggressive scraping.

• This technique is most commonly used in diagnosing tinea corporis or tinea pedis.

• Although a lower sensitivity is found with this diagnostic test for tinea capitis, spores within hair shafts can be visualized in “black dot” type.

• Samples should be collected from the advancing edge or margins of skin lesions with the edge of a scalpel.

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  • In children, use the dull edge if they are moving or use a cytobrush.

  
  

  • The foman blade, a 2-sided, spatula-type instrument, is less likely to cut the skin of a moving infant.

• Shavings of nails left in KOH for several hours may assist in diagnosis of onychomycosis.

• KOH is used to digest the proteins, lipids, and epithelial debris in the specimen.

• Gentle cleaning of the area to be tested with an alcohol wipe before this examination may remove confusing oil drops and excess debris from the slide.