Tinea nigra is an infection of the skin. It affects the outermost layer of skin. The infection will cause a black or brown patch on the skin. Except for the dark patch, tinea nigra is a harmless condition.

Tinea nigra usually affect the palms of the hands or soles of the feet. It may also appear on the neck or trunk.

Cross-Section of Skin
skin layers cross section
Tinea nigra affects the topmost layer of skin.
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Tinea nigra is caused by a fungus. The type of fungus that causes this infection is most often found in rotting wood, soil, compost, or sewage. The fungus may enter your body through a break in your skin.