<unk> 's<unk>  can usually be diagnosed by visual inspection of the skin, but where the diagnosis is in doubt direct microscopy of a potassium hydroxide preparation (known as a KOH test).
A KOH preparation is performed on skin scrapings from the affected area.
The KOH preparation has an excellent positive predictive value, but occasionally false negative results may be obtained, especially if treatment with an anti-fungal medication has already begun.
Athlete's foot laboratory findings
Diabetic foot laboratory findings
Gangrene laboratory findings
Varicose veins laboratory findings
Peripheral arterial disease physical examination
Scleroderma physical examination
Athlete's foot other diagnostic studies
Buerger's disease physical examination