Definition

Tinea nigra is an infection of the outer layer of skin. A black or brown patch forms on the skin. It often affects the palms of the hands and soles of the feet. It may also appear on the neck or trunk. Tinea nigra is a harmless condition.

Cross-Section of Skin

Tinea nigra affects the outermost layer of skin.

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Causes

Tinea nigra is caused by a fungus. The fungus is found in rotting wood, soil, compost, or sewage. The fungus may enter the body through a break in the skin.

Risk Factors

Tinea nigra is most common in subtropical and tropical areas. The risk is highest in those who live or travel to areas such as:

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

Symptoms

Symptoms of tinea nigra are a brownish-black patch on the skin that:

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

It may be mistaken for a type of skin cancer.

Diagnosis

The doctor will ask about your symptoms and health history. A physical exam will be done. You may see a skin doctor.

A small sample of the affected skin will be scraped and tested. This will confirm the diagnosis.

Treatment

Tinea nigra is usually treated with antifungal skin creams.

Prevention

To reduce the risk of tinea nigra:

• If living in or traveling to high-risk areas:
  • Avoid contact with rotting wood, dirt, sewage, or compost.
  • If working with materials listed above, wear gloves and other protection.