What are causes of vertical dark line on big toe? – Dr. Rajdeep Mysore

A vertical dark line, we call it as longitudinal melanonychia. A longitudinal melanonychia is very common in dark skinned people and doesn’t indicate that you have melanoma. In fair skinned people, I don’t mean Indians, I mean Caucasians and Europeans, and you have a longitudinal black line on your nail, then you do have to be concerned about melanoma. The characters of longitudinal line due to melanoma are slightly different from other causes. Other causes are common congenital cause like people who have moles in other parts of their body. Moles can even occur on the nail matrix and when the nail grows, it leads to longitudinal lines along the nail. So it is nothing but a mole in most of the people. If somebody in your family had cancer, then you can get a biopsy done from the nail matrix to rule out melanoma. In a biopsy, the pathologist rules out if there are any cancerous cells in that sample.If you have normal nevus cells or mole cells, then you don’t have to be worried.