What Is Tinea Nigra?

Tinea nigra is a fungal infection marked by ring-shaped brown or black patches on the soles of the feet and palms. It is most often seen in people living in tropical or coastal areas. Tinea nigra is caused by black mold called Hortaea werneckii, which is found in soil.

Tinea nigra is a superficial fungal infection affecting the epidermis, or top layer, of skin. This condition is uncommon. However, it can be confused with other conditions, such as melanoma, which must be ruled out. This article will discuss the symptoms, causes, diagnosis, and treatment of tinea nigra.

Causes of Tinea Nigra

Hortaea werneckii, a black mold found in soil, is the cause of tinea nigra. Additionally, some conditions can increase its likelihood, including:

• Living in a tropical climate or the southeast coastal area of the United States
• Sweating excessively (hyperhidrosis)
• Broken skin that is exposed to soil, sewage, wood, or compost
• Being a young adult or child

The mold likes salt and warmth, which is why it is found mostly in places where those factors are plentiful. The mold can enter the body through broken skin or with trauma. It produces a black pigment that is much like the melanin pigment in human skin.

Tinea Nigra Symptoms and Appearance

Symptoms of tinea nigra include:

• Black or brown patches with a darker border
• Black or brown patches that seem to grow with time
• Tiny brown or black dots that gather into patches
• Usually only one patch
• Often seen on palms or soles, sometimes on or between fingers or toes
• Usually has no pain, scaliness, or other symptoms
• Itchiness or scaliness in some cases

Is Tinea Nigra Infection Contagious?

Tinea nigra is not transmitted from person to person. It is more likely to occur when broken skin is exposed to dirt or soil.

Diagnosing Tinea Nigra

Since tinea nigra is uncommon and mimics other more common disorders, it can be mistaken for conditions like:

• Melanoma, a skin cancer marked by distorted moles
• A benign mole
• Skin reactions that cause discoloration

To diagnose tinea nigra, a healthcare provider might do the following:

• Use a dermoscope to examine the lesion visually
• Scrape a skin sample to examine for fungi under a microscope
• Take a skin biopsy (removing of skin for examination in the lab) to rule out cancers

Although common in subtropical areas such as Central America and South America, tinea nigra is now also appearing in areas of more temperate climates, including the United Kingdom, France, Spain, and the United States.

Treating Tinea Nigra

Tinea nigra is treated with:

• Exfoliating creams with ingredients like salicylic acid
• Antifungal creams like thiabendazole or imidazole
• An iodine solution

Symptoms can take two to four weeks to clear up when treated with antifungals. The condition rarely goes away without treatment.

Complications of Tinea Nigra

Tinea nigra is mostly a cosmetic disorder. Complications are rare in healthy people. Complications of tinea nigra include:

• Patches that continue to grow larger and become chronic (lifelong)
• Infections for people with compromised immune systems, who might experience infections in the blood or organs caused by untreated tinea nigra
  

When to See a Healthcare Provider

While tinea nigra is not contagious or likely to cause a further problem, skin discoloration should be tested by a healthcare professional to rule out skin cancer. In addition, untreated tinea nigra could cause the patches to grow larger and become a long-term cosmetic concern.

Summary

Tinea nigra is an uncommon fungal infection (caused by a black mold) that appears as brown-black patches on the palms and soles of feet that are painless and have no other symptoms. It is usually found in countries with tropical climates and some coastal areas of Europe and North America.

Tinea nigra is caused by contact between broken skin and infected soil, sewage, wood, or compost. It is more likely to occur in unhygienic living spaces, among children or young adults, and in people who sweat excessively.

You should see a healthcare provider when you have symptoms of tinea nigra as it can mimic melanoma, which must be ruled out. Diagnosing tinea nigra usually involves a dermoscopic examination, a skin scraping examination, and sometimes a skin biopsy.

Tinea nigra can be treated with antifungal creams or exfoliants. Sometimes, iodine solutions can also treat the skin condition.