Tinea nigra is a type of dermatomycosis. A dermatomycosis is a fungal infection of the skin. Tinea nigra affects the outermost layer of skin, called the stratum corneum. Tinea nigra causes a black or brown patch on the skin. Although a patch of tinea nigra may be mistaken for the more serious skin discolorations of melanoma, tinea nigra is actually a very benign condition that often causes no symptoms apart from its appearance.

Causes

Tinea nigra is caused by a fungus called Hortaea werneckii that lives in rotting wood, soil, compost, or sewage. You may contract the fungus if you are around any of these materials and you suffer an injury that involves a break in the skin.

Risk Factors

Individuals more likely to develop tinea nigra are:

• Children

• Young adults

• Females

• Living or traveling in tropical or subtropical areas, such as:

• • South Africa

• • Brazil

• • Panama

• • Cuba

• • Puerto Rico

• • Coastal areas along the Southeastern seaboard of the United States

Symptoms

Tinea nigra causes a brownish-black patch on the skin. The area tends to expand over time, has an irregular shape, and often sports a darker border. Sometimes the area is itchy or scaly. Patches usually affect the palms of the hands or soles of the feet. Occasionally, patches may appear on the neck or trunk.

Diagnosis

Your doctor will ask about your symptoms and medical history, and perform a physical exam. You may need to see a dermatologist for testing, diagnosis, and treatment of this condition. Tinea nigra is diagnosed by scraping a small sample of the affected skin. The sample is cultured in a laboratory and examined under a microscope, where the fungi can be identified.

Treatment

Talk with your doctor about the best treatment plan for you. Tinea nigra is usually treated with topical medications that can be applied to the affected area of skin, such as:

• Whitfield’s Ointment

• 2% miconazole cream

• 2% ketaconazole cream

• 5-10% salicylic acid ointment

Prevention

To help reduce your chances of getting tinea nigra, take the following steps:

• Use care when traveling in areas where tinea nigra may be contracted

• Avoid contact with potentially infected material, such as rotting wood, dirt, sewage, or compost

RESOURCES:

American Academy of Dermatology
http://www.aad.org/

Dr. Fungus
http://www.doctorfungus.org

CANADIAN RESOURCES:

BC Health Guide, British Columbia Ministry of Health
http://www.bchealthguide.org

Canadian Famiily Physician
(the official publication of the College of Family Physicians of Canada)
http://www.cfpc.ca/cfp/

References:

Gupta AK. Tinea corporis, tinea cruris, tinea nigra, and piedra. Dermatological Clinics. 2003; 21; 395-400.

Habif TP. Clinical Dermatology, 4th ed. St. Louis: Mosby, 2004.

Mandel GL, Bennett JE, Dolin R. (eds). Principles and Practice of Infectious Diseases, 6th ed. Philadelphia: Elsevier, Inc., 2005.