How is ringworm diagnosed?
Often, the diagnosis of ringworm is obvious from its location and appearance. Otherwise, skin scrapings for microscopic examination and a culture of the affected skin can establish the diagnosis of ringworm. If the diagnosis is unclear, a potassium hydroxide (KOH) preparation of a skin scraping can be reviewed under the microscope to confirm the diagnosis of a fungal dermatophyte infection. If a dermatophyte infection is present and the skin problem is misdiagnosed, inappropriate treatment might be prescribed that could actually worsen the infection.