"lump" on left testicle

I found a lump on my testicle quite a while ago, and it has always been that size, and never got any bigger or smaller. I was getting quite worried about it, to the extent of checking it every couple of hours but there was absolutely no change. If i pull the scrotum skin tight you can see that it is a blue tubular shape, like a thick vein. Is it possible to have thick veins on side of testicle?

Forgot to add, im 15 if this helps.