Tinea nigra is a superficial fungal infection impacting the outermost layer of the skin. This condition, characterized by dark discoloration, is not contagious from person to person through direct contact. It presents as a cosmetic concern rather than a health risk.
What is Tinea Nigra?
Tinea nigra appears as a dark brown to black patch on the skin. These patches are irregular in shape, well-demarcated, and non-scaly, often resembling a stain or a mole. The discoloration is due to pigments produced by the fungus. While it can occur on other body parts, it commonly affects the palms of the hands and the soles of the feet. This infection is asymptomatic, causing no pain, itching, or discomfort.
The fungus responsible for tinea nigra is primarily Hortaea werneckii, a pigmented yeast. This organism lives in the stratum corneum, the outermost layer of the epidermis, and does not invade deeper tissues. Tinea nigra is a harmless condition, posing no serious health risks.
How Tinea Nigra Spreads (Or Doesn’t)
Tinea nigra is not transmitted through direct contact with an infected person or animal. The fungus resides solely in the superficial layer of the skin, preventing person-to-person transmission. This characteristic differentiates it from many other common skin infections.
Acquisition of tinea nigra occurs through environmental exposure to Hortaea werneckii. This fungus thrives in specific environments, including soil, decaying organic matter, and saltwater, particularly in tropical and subtropical regions. Activities that increase the risk of exposure include walking barefoot on contaminated surfaces or handling soil and vegetation without protective gear. The fungus can enter the skin through minor cuts or abrasions.
Identifying Tinea Nigra
Individuals might first notice a persistent dark spot on their palm or sole that does not wash off. Tinea nigra can be mistaken for more serious skin conditions, such as moles or melanoma. Therefore, seeking professional medical evaluation is advisable for any new or changing pigmented skin lesion.
A healthcare professional diagnoses tinea nigra based on its distinctive appearance. Confirmation involves a skin scraping from the affected area. This sample is then examined under a microscope after being treated with a potassium hydroxide (KOH) solution, to identify characteristic fungal elements. Fungal cultures can also be performed to grow and identify Hortaea werneckii.
Treatment and Prevention
Tinea nigra is treatable with topical antifungal medications. Commonly prescribed creams include those containing miconazole or terbinafine, applied to the affected area for a few weeks. The infection resolves completely with consistent application. In some instances, a healthcare provider might gently scrape the lesion to help remove the fungus before or during treatment.
Preventative measures focus on minimizing contact with the fungus in its natural habitats. When in tropical or subtropical regions, wearing protective footwear is recommended, especially when walking on soil or beaches. Wearing gloves while gardening or handling decaying organic matter can also reduce exposure. Maintaining skin hygiene after outdoor activities in at-risk environments can aid prevention.