Skin scraping is a diagnostic procedure done by dermatologist in their rooms to obtain a superficial layer of the dead skin. This procedure is most often used to diagnose fungal infections (skin, hair and nails) and parasitic infections like scabies.
If a dermatologist suspects a parasitic or fungal infection of the skin, they may choose to use skin scrapings of affected sites in order to obtain a sample of tissue.
- Skin scrapes are usually done in areas with visual signs of infestation or infections.
- Depending on the sample site, a small window of hair may first have to be shaved away. If the infection is suspected under the fingernails or toenails, the nails will first be trimmed back. After which, the area will be sterilized with alcohol.
- The dermatologist will use a scalpel blade to scrape perpendicularly across the skin onto a glass slide.
- To prepare the glass slide, a few drops of KOH will be added to the skin sample, and then a cover slip will be placed over the top.
- The dermatologist will then view the slide starting at low light and magnification under the microscope. If hyphae or pseudohyphae are visualized, there is a strong likelihood of a dermatophyte (fungal) or yeast infection, respectfully. Scabies mites can also be visualized in the same way.
- If the KOH preparation turns out negative, there may still be need for a fungal or yeast culture to confirm the diagnosis as the might be sampling errors.