To confirm whether fine needle aspiration biopsy (FNAB) can avoid close monitoring, a source of worry for women patients with a suspected fibroadenoma found by ultrasound, and requiring their compliance.

Over 39months, 427 nodules with a diagnosis of fibroadenoma were sampled in 372 patients using ultrasound-guided FNAB. The sonographic appearance of all the nodules suggested BI-RADS category 3 fibroadenomas. The mean size of the fibroadenomas was 9mm. The mean duration of follow-up was 29.7months.

Seven nodules had atypical cytology: a microbiopsy and/or excision found a simple fibroadenoma (n=3), mastitis (n=1), a fibroadenoma associated with a papilloma (n=1), fibrosis (n=1) and normal tissue (n=1). Seven other nodules were resected during treatment for synchronous cancer, and were diagnosed as fibroadenomas. Two hundred and seventy-six nodules were followed-up (121 patients were lost to follow-up [n=132]) and the appearance of 263 nodules (95.29%) was stable. Seven nodules, which had increased in size, underwent another FNAB or microbiopsy or surgery. Five nodules were not found again. The borders of one nodule showed modifications.

The use of fine needle aspiration biopsy, interpreted by an experienced cytologist, means that short term follow-up of fibroadenomas can be avoided.