Lump of unknown origin

I have a lump in my left breast at about 4 oclock. I had a mammogram and an ultrasound about a year ago, and the radiologist advised that both procedures were to be repeated in about six months. I had the follow up procedures six months ago. There was no change in the lump and no calcifications that could be seen. My doctor advised me to wait another six months and see if there was any change. The radiologist cannot say what this lump is made up of. It does not appear to be a simple cyst but they cannot say for sure if it is a complex cyst. As of late I have had a dull ache and some tenderness and swelling in that breat in the area of this lump. This is not a large mass, it was less than 4cm on the last ultrasound. I have a history of cystic breasts, but all prior cysts that did not resolve themselves were easily aspirated and did not recur. Should I be more concerned with this? Should I insist that this area be biopsied? I am 39 years old with only my maternal grandmother who has a history of breast cancer and she was not diagnosed until she was over the age of 80.
Thank you
Lori

[CCF-RN,MSN-rf]

Dear johlor:  If there is a mass and neither the radiologist nor the physician can say that it is not cancer, I would consider the opinion of a breast surgeon.  In many cases these problems can turn out to be benign but the only way to know for certain may be to biopsy.