When David Edges's wife spotted a faint brown line on his toenail, he didn't think it was anything to worry about. But Kelly, ...

a brown line in your nail bed can alert you to the presence of some cancers. But what about what’s happening under the nail?

Medically reviewed by Susan Bard, MD A black line on the nail could be normal, such as when it is just a color variation.

This is also the case if you see dark lines underneath the nail, as although this can be caused by trauma, it could also be a sign of subungual melanoma, a rare but serious type of skin cancer.

These reddish-brown streaks are 1-3 millimeters long ... Splinter hemorrhages look like dark, vertical lines under your nails. They can affect your fingernails or toenails. The most common cause ...