Definition | Causes | Risk Factors | Symptoms | Diagnosis | Treatment | Prevention

Definition

Tinea nigra is an infection of the skin. It affects the outermost layer of skin. The infection will cause a black or brown patch on the skin. Except for the dark patch, tinea nigra is a harmless condition.

Tinea nigra usually affect the palms of the hands or soles of the feet. It may also appear on the neck or trunk.

Cross-Section of Skin

skin layers cross section
Tinea nigra affects the topmost layer of skin.
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Causes

Tinea nigra is caused by a fungus. The type of fungus that causes this infection is most often found in rotting wood, soil, compost, or sewage. The fungus may enter your body through a break in your skin.

Risk Factors

You are more likely to develop tinea nigra if you have been living or traveling in tropical or subtropical areas, such as:

  • South Africa
  • Brazil
  • Panama
  • Cuba
  • Puerto Rico
  • Coastal areas along the southeastern United States

Symptoms

Tinea nigra causes a brownish-black patch on the skin that:

  • Has an irregular shape with a darker border
  • May be itchy or scaly
  • Tends to expand over time

A tinea nigra patch may be mistaken for a type of skin cancer. Talk to your doctor about any skin growth or changes.

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will be done. You may need to see a skin specialist for tests, diagnosis, and treatment.

Tinea nigra is diagnosed by scraping a small sample of the affected skin. The sample is examined under a microscope.

Treatment

Tinea nigra is usually treated with an antifungal medication. The medication is placed on the skin as creams or ointments.

Prevention

To help reduce your chance of tinea nigra:

  • Use care when traveling in high-risk areas.
  • Avoid contact with potentially infected material, such as rotting wood, dirt, sewage, or compost.
  • If you must work with any of the materials listed above, take the proper safety steps. Wear gloves and other protective gear.