Melanonychia: Brown or Black Discoloration of the Nail
Introduction
Melanonychia is a condition characterized by the presence of brown or black discoloration in the nail. This discoloration can affect fingernails or toenails and can be caused by a variety of factors, including nail injury, fungal infection, or a more serious underlying medical condition.
Causes of Melanonychia
Nail Injury
Trauma to the nail, such as a nail bed injury, can cause blood to pool under the nail and cause brownish-black discoloration. This type of melanonychia is usually temporary and will resolve as the nail grows out.
Fungal Infection
Distal or lateral subungual onychomycosis, a type of fungal nail infection, can also cause brownish spots under the nail. This infection begins at the edge of the nail and can spread to the entire nail, causing it to become discolored and thickened.
More Serious Underlying Medical Conditions
In rare cases, melanonychia can be a sign of a more serious underlying medical condition, such as: *
Melanoma: A type of skin cancer that can affect the nail *
Addison's disease: A disorder that affects the adrenal glands *
Heavy metal poisoning: Exposure to heavy metals, such as arsenic or lead Diagnosis and Treatment
To diagnose melanonychia, a doctor will typically examine the nail and ask about your medical history. In some cases, a biopsy may be necessary to rule out more serious underlying medical conditions. Treatment for melanonychia depends on the underlying cause. For nail injury, no treatment is usually necessary and the discoloration will resolve as the nail grows out. For fungal infections, antifungal medication will be prescribed. For more serious underlying medical conditions, appropriate medical treatment will be provided.
Prevention
While not all causes of melanonychia can be prevented, there are some measures you can take to reduce your risk of developing this condition: *
Wear protective clothing and gloves: To prevent nail injuries *
Keep nails clean and dry: To reduce the risk of fungal infections *
Avoid exposure to heavy metals: If possible
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