Tinea nigra is a superficial fungal infection caused by Hortaea werneckii. Tinea nigra is uncommon in the United States, where it may be seen along the Gulf Coast. It is more commonly found in tropical regions of Central and South America, Africa, Southeast Asia, and Australia. It presents as one or more asymptomatic tan, brown, or black macules or patches, usually on the palm or sole. The palm is affected more frequently than the sole. Other areas of the body, such as the neck or trunk, can also be affected.

After contamination from an infected source (eg, soil, sand, waste, or wood), the mycosis infects the stratum corneum, resulting in a dark macule or patch as the fungal hyphae produce melanin. The incubation period is typically 10-15 days. 

The most frequently affected populations are children and adolescents (children are more prone to exposure to the fungus); however, persons of any age may be affected. 

Immunocompromised Patient Considerations
The fungus involved in causing infections of tinea nigra can lead to serious infections in immunocompromised patients. There is a risk of disseminated disease from superficial cutaneous fungal infections noted in transplant patients.