HealthSearch

Health Guide
Images

Skin lesion KOH exam

Definition

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

Alternative Names

Potassium hydroxide examination of skin lesion

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.

References

Chernecky CC, Berger BJ. Potassium hydroxide preparation (KOH wet mount) - specimen. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:898-899.

Elewski BE, Hughey LC, Sobera JO, Hay R. Fungal diseases. In: Bolognia JL, Jorizzo JL, Schaffer JV, eds. Dermatology. 3rd ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 77.


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.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.