Skin lesion KOH exam

Skin Lesion KOH Exam

A Skin Lesion KOH exam is a test used to help diagnose skin infections and other skin disorders. It is a type of microscopic examination that requires taking a small sample of the affected skin and viewing it under a microscope. The sample is treated with a solution called potassium hydroxide (KOH) which helps to make the diagnosis visible.

Preparation for the Test

In preparation for the test, the doctor will take a small sample of the skin and treat it with potassium hydroxide. The sample is then placed on a slide and covered with a special cover slip. The slides are then viewed under a microscope to determine the cause of the skin lesion.

Procedure of Test

The procedure typically begins with the doctor obtaining a sample of the affected skin. After obtaining the sample, the doctor will treat it with potassium hydroxide and then place the sample on a microscope slide. The slide is then covered with a specialized cover slip and viewed under a microscope.

Types of Skin Lesion Tests

The two main types of skin lesion tests are KOH preparation and Culture testing. KOH preparation is a type of test where the sample of skin is viewed under a microscope after being treated with potassium hydroxide. Culture testing involves growing bacteria in a laboratory in order to identify the type of bacteria present in the skin lesion.


There are generally no risks associated with a KOH preparation test. The test is considered a safe and non-invasive procedure.

Why is a KOH Exam Performed?

A KOH exam is performed to help diagnose various skin infections and disorders such as tinea, dermatophytosis, candidiasis, and other fungal infections. The test can also help determine the cause of an allergic reaction or other skin issues.

When is a KOH Exam Performed?

A KOH exam is typically performed when a person has symptoms of a skin infection or disorder, such as redness, itchiness, scaling, or other skin changes. The doctor may also order a KOH exam if they suspect a fungal infection or an allergic reaction.