What is tinea nigra?
Tinea nigra is a mould infection of the skin of the palm or sole presenting as persistent brown or black patches.
Who gets tinea nigra?
Tinea nigra is most common in tropical regions and often infects those with a tendency to excessive sweating (hyperhidrosis).
What is the cause of tinea nigra?
Tinea nigra is due to infection with a brown mould, Hortaea werneckii. This mould usually inhabits soil.
The organism's previous names include:
- Exophiala phaeoannellomyces
- Phaeoannellomyces werneckii
- Exophiala werneckii
- Cladosporium werneckii.
What are the clinical features of tinea nigra?
Tinea nigra presents as unilateral or asymmetrical brown or black patches on the palms or soles. They are slightly scaly and do not itch or sting. The patches slowly enlarge. Dermoscopy can help distinguish tinea nigra from other brown-black skin lesions.
How is tinea nigra diagnosed?
Tinea nigra may be suspected clinically but should be confirmed by mycology. Scrapings that have been taken from the edge of the scaly lesion show a mycelium. The hyphae can be clear in colour, yellow or brown, and are septate.
Culture grows black colonies of Hortaea werneckii within a week.
Mycology of Hortaea werneckii
What is the differential diagnosis of tinea nigra?
- A benign mole (naevus)
- Postinflammatory pigmentation arising after dermatitis or another skin inflammation
What is the treatment of tinea nigra?
Tinea nigra usually clears with a topical antifungal applied for 2–4 weeks.