Doctor insights on:
Lots of reasons: When you say "lines" it is difficult to say as there are many types of lines. The most common lines seen are longitudinal (running along the length of the nail). More specifically, longitudinal melanonychia means dark lines along the nails. This can be variant of normal, particularly in persons with dark skin. However, any new line of pigmentation should be evaluated by a dermatologist. ...Read more
Are splinter looking brown lines under fingernails something to worry about? There aren't any other symptoms present.
Trauma vs infection: The most common cause of splinter like hemorrhages seen through the nail in the ail bed, come from trauma. I've had them in the past from tapping my nails on the desk. I had to break the habit. Splinter hemorrhages as signs of infection are more often seen at the base of the nail near the cuticle. Again, the most common cause of these hemorrhages is trauma, even as minor as tapping your nail. ...Read more
Purple line on nail: Fingernails can have many different signs. Purple lines may represent a couple different things; mole/freckle at the nail base or splinter hemorrhage. The latter is not specific to any disease state, but may be a sign of something else that is going on. If you recently injured your nail bed, that might be a sign of bruising. http://en.wikipedia.org/wiki/splinter_hemorrhage. ...Read more