Fibroadenoma is the most common tumour of the breast. It occurs in 25 percent of asymptomatic women, usually with a peak incidence in early reproductive life between the ages of 15 and 35.
It is conventionally regarded as a benign tumour of the breast, and is thought to represent a harmless overgrowth of breast tissue. It is hormone-dependent and may enlarge during pregnancy, and involutes (shrinks) with the rest of the breast after menopause.
Fibroadenoma has no known risk factors and is thought to be caused by female hormones.
Fibroadenoma often presents as a painless, highly mobile, firm nodule within the breast.
They may also be detected upon routine breast imaging i.e. mammography or ultrasound examination.
Clinical breast examination often reveals the characteristic ‘breast mouse’ which is a nodule that is very mobile within the breast. Mammograms and breast ultrasound are often used depending on the risks, and diagnosis can be confirmed by core needle biopsy or excision biopsy.
A fibroadenoma may be monitored for long-term stability or they may be removed by vacuum-assisted needle biopsy (VAB) or surgery.
It may be difficult to differentiate a large fibroadenoma from the phyllodes tumour, another type of breast tumour, based on ultrasound or even core needle biopsy. If the latter is suspected, surgical excision with a margin to completely remove the tumour is recommended.
Simple fibroadenomas do not increase the risk of breast cancer.