I have a breast fibroid. I am 20. Will needle biopsy leave a scar? I am worried.

No scar. Needle biopsy won't leave a scar. A small needle is used.
There may be. A tiny scar at the needle entry site or skin nick which will likely fade with time.
No scar. A needle biopsy will be similar to receiving a vaccination, in terms of needle size, if you have the simplest procedure - a fine needle aspiration. A slightly bigger biopsy - a needle core biopsy, is unlikely to be necessary to diagnose your lump. Even with a needle core, the mark remaining is smaller than a pimple and in most cases resolves completely!