Dear hope1962, A fibroadenoma is a benign (non-cancerous) growth. As long as the doctor is sure it is a fibroadenoma, there is no need to remove it, unless it is causing discomfort. In 50% of the cases fibroadenomas will go away on their own within 5 years. In others, the life of a fibroadenoma is about 15 years. In teenagers - the tendency is not to remove fibroadenomas. In middle age women, the tendency is to remove the fibroadenomas to be sure they are, in fact, fibroadenomas. As this has been biopsied the question would be how sure the core biopsy was a representative sample of the whole. Over the internet without having access to the films, biopsy results and ability to put this in context of your situation it is impossible to say what we would advise in your individual situation. Another option for you would be to have a tie breaking third opinion.
I had the same thing three years ago. After a biopsy revealed it to be benign I went ahead and had it removed. I have dense breast tissue and felt it was better to have it removed so nothing could hide behind it in the future. I was 43 at the time