nothing found, breast lump causing pain.

Hi there,
Im a 19 y/o girl,
I had a nipple piercing in my right breast about 8 months ago, and took it out due to infection.
I went to the doctors and was put on medication to treat it,
Not long after the infection went away...
I discovered a lump in my breast.
doctors thought it was part of the infection, but sadly it didnt go away after another set of antibiotics.
I have now been for two ultrasounds and still no results or conclusion as to what it is.
in the recent months i have been getting sometimes sharp pain, but also accute. then spreading to under my arm and appoisite where the lump is. so the lump is at 2'oclock and the pain has reflected to 7/8 o'clock.
the lump has actualy grown, and now is roughly 2x4cm.
I am having a biopsy done in near future but still am quite concerned as to what this is.
if someone could please give me an idea and closure.
the ultrasounds showed literally nothing. I have been told that they should be able to pick up whatever it could be.
not even a sign of blockage or a cyist.
thank you for your time and sorry to ramble on.

[zouzi]

Hi,  
Not all palpable masses will appear on an ultrasound or mammogram.  Each test has it's limitations and what it can pick up.In this case a biopsy is usually recommended.  
If the lump can be felt and it's a cyst, a needle biopsy FNA ( Fine Needle Aspiration) will make it collapse and no further treatment will be necessary.If the lump is a solid one, the needle can sample it so that the cells extracted can be examined by a pathologist.A lump is a lump and it really doesn't matter what the mammogram or ultrasound show.I would guess that this could be an abscess or a benign growth like a cyst or a fibroadenoma which is very common in your age group.  
Please don't jump to any conclusion...the fact that this lump is palpable but does not show on radiology, does not make it cancerous or increase the chances of it being cancerous.
Hoping that all goes well for you. :)
Best wishes...