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 common 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. Tinea nigra is uncommon; however, it can be confused with other conditions.

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

Tinea Nigra Symptoms and Appearance

Symptoms of tinea nigra include:

  • Black or brown patches with a darker borderBlack or brown patches that seem to grow with timeTiny brown or black dots that gather into patchesItchiness or scaliness in some cases

Is Tinea Nigra Infection Contagious?

Tinea nigra can be contagious, especially for people and children living in unhygienic environments. It is also more likely to occur when broken skin is exposed to dirt or soil.

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.

Complications of Tinea Nigra

Tinea nigra is mostly a cosmetic disorder, and life-threatening 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

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:

  • Scrape a skin sample to examine for fungi under a microscope
  • Take a skin biopsy to rule out cancers

When to See a Healthcare Provider

While tinea nigra is not contagious or deadly, 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. 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 and among children or young adults, and among people who sweat excessively.

Tinea nigra can be contagious and treated with antifungal creams or exfoliants. Sometimes, iodine solutions can also treat the skin condition. Diagnosing tinea nigra usually requires a biopsy or skin culture since it can be confused for melanoma or skin discoloration.