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What Is Tinea Nigra?

Medically Reviewed by Dan Brennan, MD on June 05, 2021

‌Tinea nigra is a dark patch of infected skin. It only affects the most surface-level layer of your skin and is not a dangerous condition. It’s not very common, but you’ll recognize it for the unique effect it has on your skin.

It’s most likely to affect your extremities and shows up more often in tropical climates. Tinea nigra is treatable and doesn’t usually have long-term effects on your health.

‌Read on to find out more about tinea nigra, along with its symptoms, causes, and treatment.

Symptoms of Tinea Nigra

‌Tinea nigra can show up on your skin as a rough, brown or black patch. You might mistake it for skin cancer because it gets bigger over time. But a visit to your doctor can clear up any confusion. Your dark spot will be different from skin cancer because it will have an odd shape with a noticeably darker border.‌

If you have tinea nigra on your hands, you might find that its color changes throughout the day. It is reported to vary from a dark color in the morning to a lighter color in the evening. This can be a result of using your hands to carry out activities during the day.

Another distinctive sign of tinea nigra is where it appears. Tinea nigra commonly affects the palms of your hands and the soles of your feet. It can also develop on your neck. Because tinea nigra doesn’t cause discomfort, you might have it for years before you actually get it tested.

Causes of Tinea Nigra

‌This skin infection happens after you come in contact with a fungus called Hortaea werneckii. Hortaea werneckii thrives in hypersaline environments or bodies of water with extremely high salt content. For example, the Dead Sea, which is one of the saltiest lakes in the world, is a hypersaline environment.

Tinea nigra has a long incubation period. This means that it doesn’t show up immediately after you come in contact with Hortaea werneckii. You’ll see color changes in your skin at least 2 to 7 weeks after your exposure to the fungus.‌

You’ll find Hortaea werneckii in rotten wood, dirt, composted materials, and sewage, which you’re likely to step on or touch. The fungus can enter and infect your body through even the smallest cut or opening in your skin.

Many reported cases of tinea nigra come from humid, tropical areas. If you live in any of the following areas, you’re more likely to get this skin infection:‌

  • Panama
  • Colombia
  • Venezuela
  • Brazil
  • Mexico
  • India
  • Sri Lanka
  • Myanmar
  • Polynesia

‌‌Tinea nigra is extremely uncommon in Europe and the United States. But it’s still possible to get it in one of these places. If you have hyperhidrosis, or excessive sweating, or live near the ocean, your chances of getting tinea nigra can increase.

Prevention of Tinea Nigra

Tinea nigra can be difficult to prevent because of its subtle and unique cause. You should avoid touching Hortaea werneckii, especially if you have any open cuts. If you can, you should stay away from the places where it’s most often found.

Risks of Tinea Nigra

‌There are no serious risks or complications that come along with tinea nigra. It’s a superficial skin infection that only changes the color and possibly texture of a small area of your skin. It is not dangerous, but you may want to get rid of it for cosmetic purposes.

Treatment of Tinea Nigra

‌If you think you might have tinea nigra, you should see a dermatologist. Your infection may clear up on its own, but it’s not likely.

Your dermatologist will scrape off a sample of the infected area to test whether you have tinea nigra. This is a quick way to confirm that you have tinea nigra and not skin cancer. If your test comes back positive, you can treat your infection with antifungal skin cream.

The antifungal skin cream will clear up your tinea nigra after 2 to 4 weeks of consistent use. Your dermatologist may even scrape the tinea nigra with a scalpel before you start using the antifungal skin cream.

If your infection goes away but your skin still has dark coloring, you can try scrubbing it. You can also apply a keratolytic agent like salicylic acid to soften and moisturize the healed skin.

Tinea nigra is easy to diagnose and treat. If you think you have it, visit your doctor to make sure that it’s a harmless skin infection.

WebMD Medical Reference

Sources

SOURCES:

Anais Brasileiros de Dermatologia: “Scanning electron microscopy of tinea nigra.”

Beth Israel Lahey Health Winchester Hospital: “Tinea Nigra.”

‌Dermatology Online Journal: “Dermatoscopy in the diagnosis of tinea nigra.”

Medscape: “Tinea Nigra.”

Studies in Mycology: “Tinea nigra by Hortaea werneckii, a report of 22 cases from Mexico.” 

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