Dark Lines on Toenails

Dark lines on the toenails are often seen in the office and asked about by patients.  Although most cases of dark nails are benign melanin in the nail root, a small percentage may represent melanoma, a potentially fatal cancer. Pigmentary changes in nail appearance may occur from trauma, inflammatory disease, occupational exposure, fungal infections, etc.

The deposition of melanin, or dark lines in the nail plate, can be caused by:

• mole or birthmark in the nail root;
• dark spots in the nail root;
• nail tumors, such as squamous cell carcinoma;
• human immunodeficiency virus (HIV) infection;
• inflammatory nail disorders;
• trauma;
• pregnancy;
• medications;
• endocrine disorders, such as Addison’s disease and Cushing’s disease; and/or
• melanoma.

Acral melanoma tumors are an aggressive type of cancer and have a poorer survival outcome.  It is the most common type of melanoma in dark-skinned individuals, and is mostly diagnosed between the ages of 40 and 70.  This can be confused with ethnic or racial pigmentation, which, also in darker-skinned individuals, dark lines on the nails can commonly occur in one or multiple nails, and is mostly benign.

Read what the warning signs are for cancer with dark lines on toenails.

If you suspect that you have melanoma cancer according to either of the criteria above, please contact Dr. John Hoy at Seattle Foot and Ankle Center in Seattle, Washington, to discuss a biopsy procedure to rule out cancer.

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