A dark line on your nails
What does fingernails say about your health? MORE THAN YOU MIGHT THINK!
In fact, fingernails can reveal just as much about your health as your skin.
And although some marks could be because of something like a nutrient deficiency or even something you inherited from your parents, a more serious one you should be concerned about are dark brown or black lines across the nail.
This particular mark could be a sign of nail or subungual melanoma which appears under the nail and affects only 0.7 to 3.5 percent of people with melanoma.
According to the American Academy of Dermatology, other suspicious dots on your nail could be more signs of melanoma, too, including darkened skin around the nail, blood, and splits in the nail.
