Many causes: It would be helpful to know how wide it is. I am assuming as well it is a lengthwise line? A lot of times these are like moles on the skin under the nail. Sometimes also caused by vitamin deficiencies, previous trauma to the nail, medications, other systemic diseases,or worst skin cancer. Maybe have your doc check it out and make sure nothing else serious is going on in your body.
Answered 9/28/2016
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A doctor has provided 1 answer
A doctor has provided 1 answer
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