This fibroadenoma was diagnosed on which imaging modality - Mammogram or USG? Secondly why was the investigation done - as a part of routine screening or patient presented with lump in breast?
Also please rule out family history especially for breast and ovarian cancer, diagnosed before 50 years of age.
If the clues point towards a probable malignancy, then kindly consider following
1. Detailed history and physical examination - with special focus on - lump in breast/ axillary lymph nodes
2. BIRADS III - refers to probably benign, requiring close follow up, so one option is close observation and repeat imaging after 3-6 months.
3. If history and examination point towards suspicion for cancer, you can consider biopsy - core biopsy.
4. If its benign, then a simple follow up with monthly self breast examination is all that is required.
I hope I have answered your query, kindly feel free to contact for further doubts.