Skin lesion KOH exam

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Viral lesion culture

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

Potassium hydroxide examination of skin lesion; Fungal wet prep

The lesion is scraped, using a blunt edge such as the edge of a microscope slide. The scrapings from the skin lesion are placed in a solution of potassium hydroxide (KOH) and examined under the microscope. The fungus can be seen, if present. This test is different from a saline (salt water) examination, since the KOH destroys all non-fungal cells, making it much easier to see the fungal material.

There is no special preparation for the test.

You may feel a pressure sensation when the lesion is scraped from the skin.

The test is performed when fungal infections of the skin are suspected.

Review Date: 07/22/2005
Reviewed By: Jonathan Kantor, M.D., Department of Dermatology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.