Skin lesion KOH exam

Definition

The skin lesion KOH exam is a test to diagnose a fungal infection of the skin.

How the Test is Performed

The health care provider scrapes the problem area of your skin using a needle or scalpel blade. The scrapings from the skin are placed in liquid containing the chemical potassium hydroxide (KOH). The liquid is examined under the microscope. KOH destroys all non-fungal cells. This makes it easier to see if there is any fungus.

How to Prepare for the Test

There is no special preparation for the test.

How the Test will Feel

You may feel pressure or pain when the provider scrapes your skin.

Why the Test is Performed

This test is done to diagnose a fungal infection of the skin.

Normal Results

No fungus is present.

What Abnormal Results Mean

Fungus is present. The fungus may be related to ringworm, athlete's foot, jock itch, or another fungal infection.

If the results are uncertain, a skin biopsy may need to be done.

Risks

There is a small risk of bleeding or infection from scraping the skin.


Review Date: 4/14/2017
Reviewed By: Kevin Berman, MD, PhD, Atlanta Center for Dermatologic Disease, Atlanta, GA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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