Usually, dermatophyte infections can be diagnosed by their appearance. However, a confirmatory rapid in-office test can also be conducted, which entails using a scalpel to scrape off a lesion sample from the nail, skin, or scalp and transferring it to a slide. Potassium hydroxide (KOH) is added to the slide and the sample is examined with a microscope to determine presence of hyphae. Care should be taken in procurement of a sample, as false-negative results may occur if the patient is already using an antifungal, if too small a sample is obtained, or if sample from a wrong site is collected.