Hello. All black lines on toes are not melanomas or cancer. There are several other causes of black line, also called longitudinal melanonychia. These include injury, medications like minocycline, antimalarials, hydroxyurea etc., skin disorders like lichen planus, nevus (counterpart of birth marks in adults), fungal infection of nail plate and last and most common cause in Indian population being the genetic cause.
Take care and don't worry. But nevertheless visit a good dermatologist in your area to find out the cause of your problem.
Answered2017-01-13 07:03:16
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