Summary about Disease
Tinea nigra is a superficial fungal infection of the stratum corneum (outermost layer) of the skin. It is characterized by a painless, brown to black, non-scaly macule (flat spot) most commonly found on the palms of the hands, but can also occur on the soles of the feet or other areas. It is a relatively rare and benign condition, usually easily treated with topical antifungal medications.
Symptoms
The primary symptom of tinea nigra is a single, painless, brown to black macule (flat spot) on the skin. The macule is typically well-defined and non-scaly, but may occasionally be slightly scaly. It often resembles a stain, birthmark, or melanoma. It usually does not itch or cause any other discomfort.
Causes
Tinea nigra is caused by the fungus Hortaea werneckii. The infection is acquired through direct inoculation of the fungus into the skin, often through minor trauma or cuts. The fungus is commonly found in soil, decaying wood, and seawater, particularly in tropical and subtropical regions.
Medicine Used
Tinea nigra is typically treated with topical antifungal medications. Commonly used medications include:
Topical azoles: such as ketoconazole, miconazole, clotrimazole, or econazole creams.
Terbinafine cream or solution: an antifungal medication that inhibits ergosterol synthesis.
Whitfield's ointment: a combination of benzoic and salicylic acid.
Is Communicable
Tinea nigra is generally considered not highly communicable. While the fungus *Hortaea werneckii* can be found in the environment, transmission usually requires direct inoculation into the skin, typically through a break in the skin. Person-to-person transmission is rare.
Precautions
While not highly contagious, general precautions can help prevent infection, especially in endemic areas:
Avoid direct contact with soil, decaying wood, and seawater, especially if you have any cuts or abrasions on your skin.
Wear gloves when gardening or working with soil or wood.
Practice good hygiene: Wash hands thoroughly with soap and water, especially after potential exposure.
Promptly treat any cuts or abrasions to prevent fungal entry.
Avoid sharing personal items such as towels.
How long does an outbreak last?
Without treatment, the lesion may persist indefinitely. However, with appropriate topical antifungal treatment, the infection usually clears within 2 to 4 weeks.
How is it diagnosed?
Diagnosis of tinea nigra usually involves:
Clinical examination: A doctor examines the characteristic brown to black macule.
Microscopic examination: Scraping the lesion and examining it under a microscope after treatment with potassium hydroxide (KOH) reveals the presence of characteristic dematiaceous (darkly pigmented) hyphae.
Fungal culture: Culturing the skin scraping can confirm the diagnosis and identify the specific fungal species (Hortaea werneckii).
Timeline of Symptoms
The timeline of symptoms is usually slow and gradual.
Initial infection: Fungus enters the skin through a small cut or abrasion.
Gradual appearance: A light brown macule appears, which slowly darkens over weeks or months.
Stable lesion: The lesion remains relatively unchanged in size and shape unless treated.
Important Considerations
Differential diagnosis: Tinea nigra can be mistaken for other skin conditions, such as melanoma, nevus (mole), or other forms of hyperpigmentation. Therefore, proper diagnosis by a healthcare professional is essential.
Geographic location: Tinea nigra is more common in tropical and subtropical regions. Consider recent travel history when evaluating skin lesions.
Recurrence: Although treatment is usually effective, recurrence is possible if there is re-exposure to the fungus.
Immunocompromised individuals: While tinea nigra typically affects healthy individuals, those with weakened immune systems might experience more extensive or persistent infections.
Compliance with treatment: It's important to follow the prescribed treatment regimen (duration and frequency of application) to ensure complete eradication of the fungus.