Tinea nigra causes a brownish-black patch on the skin. The area tends to expand over time, has an irregular shape, and often sports a darker border. Sometimes the area is itchy or scaly. Patches usually affect the palms of the hands or soles of the feet. Occasionally, patches may appear on the neck or trunk.
Your doctor will ask about your symptoms and medical history, and perform a physical exam. You may need to see a dermatologist for testing, diagnosis, and treatment of this condition. Tinea nigra is diagnosed by scraping a small sample of the affected skin. The sample is cultured in a laboratory and examined under a microscope, where the fungi can be identified.