provide a delayed clue that something happened earlier.
This is one reason healthcare professionals may ask whether you experienced a significant illness, injury, or major health event several months before noticing a change.
A Dark Line Is Different From a Ridge
One important distinction is the difference between a ridge or groove and a dark-colored line.
A dark brown or black band running along the nail can have several possible explanations. Sometimes it results from pigmentation or minor trauma, and in some people, darker nail pigmentation can be completely benign.
