When you think of skin cancer, you probably think of looking for moles. But did you know that your nails can also reveal a sign of melanoma?

The Jean Skinner manicurist had first-hand experience to catch this stealthy symptom.

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"I had a customer studded a few weeks ago," she wrote in a post posted on Facebook in August 2017. "She had a straight, dark vertical band on her fingernail. She said as soon as she sat down: I needed a color dark enough to cover this band.

Other salons had speculated that the woman's mysterious line might be due to a calcium deficiency, a blood swelling, or a strange hereditary mark. Skinner knew better than that. She immediately informed her client that the dark line was probably an unfamiliar symptom of melanoma. Do not miss these 15 other cancer symptoms that women may ignore.

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Subungual melanoma (melanoma of the nail) is, as its nickname indicates, a skin cancer that occurs under the nail. It affects 0.7 to 3.5% of melanomas. According to the American Academy of Dermatology (AAD), it is very important to know its indicator sign: a dark or dark brown line on the finger or toenail.

Unfortunately, Skinner's intuition was correct – and the prognosis was not good. The client later called to tell him that she had an aggressive melanoma that had spread to the lymph nodes. Check out these other 10 sneaky places where you can catch skin cancer (which is not your skin).

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A black band is not the only symptom of skin cancer that could hide under your nail polish. According to the DAA, other signs of melanoma of the nail include dark skin around the nail, blood, pus and nails in the nails. Early diagnosis can be crucial. Consult your doctor immediately if you notice a dark mark under your fingernail or any other suspicious symptom. Now that you are looking at your own hand, check out these 10 surprising diseases that your hands could predict.

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