Light black line on my nail, is this skin disease?

Other conditions
1

Hey guys, 

I have a light black line on my left thumb nail for about 3-4 years now. I'm in my mid/late teens. It doesn't hurt or anything. It's just been there. 

It's about 2-3 mm wide and it runs from top to bottom of my nail and it grows as my nail grows out. But recently, I feel like it has gotten a little wider than before so I'm worried that it's some sign of skin cancer? I've never had "healthy" looking skin but I'm not exposed to the sun all the time at all and I checked my moles on my body and they are completely normal.  

I'm a little worried. Does anyone know what this is? Thanks. 

2

It's worth checking out! Can be cancer , vitamin deficiency or heart desease. I have a thin black line under my thumb nail. I never worried about it though. Had it for years. But at 57 years old I was diagnosed with heart deasease. Have had bypass surgery. Ok now , but still have the black line. Not to scare you though because it could still be a zinc defeciency. But please , go get it checked out. I should have got checked out when it appeared but waited several years. Hope this gives you a path to better health.

3

I should check it out with your doctor,

4

Are you a nail biter? That can cause those. Any damage to nail bed can do that. A wart can do that as well. Usually grows itself out as long as you arent nail biting. Easy enough to check with your doctor too, or a dermatologist.

5

I replied earlier but my reply has a word in it the caused it to be monitored. It'll probably show up tomorrow. Anyway I don't want to scar you but you should see your doctor. A black line can indicate a few things. One is a vitamin zinc defeciency, and a more serious disorder , heart desease. Your pretty young for heart desease , I would think though. I developed a thin black line on my thumb nail at around 40 years old. By the time I turned 50 , I had heart desease. So , just to be on the safe side , go see your doctor. Don't take chances , Loke I did.

6

Get this checked out,especially as you say it has got wider. You dont have to be exposed to the sun to get cancer and simply because your moles look OK doesnt mean the nails are fine.    Dont delay.  It may be nothing at all,but it needs checking.