What is a fibroadenoma?
A fibroadenoma is a benign (non-cancerous) breast lump made up of glandular and fibrous tissue. It is the most common breast lump in women under 35. It feels smooth, firm, and moveable, sometimes described as a "breast mouse" because it slides easily under the skin.
Fibroadenomas are not cancer, and they do not become cancer in the vast majority of cases. However, they should be assessed and confirmed with imaging and, if appropriate, a biopsy, because not all firm breast lumps are fibroadenomas.
Symptoms
- A smooth, firm, well-defined lump that moves freely when pressed
- Usually painless, though some women notice mild tenderness before a period
- Can be single or multiple
- Typically 1 to 3 cm in size, though giant fibroadenomas can be larger
- May grow during pregnancy or hormone use
- May shrink or disappear after menopause
Who gets fibroadenomas?
They are most common in women between 15 and 35. They can occur at any reproductive age and are the most frequently encountered benign breast lump in this age group. Family history does not significantly increase the risk.
When surgery is needed vs watchful waiting
Not all fibroadenomas need to be removed. Many small, confirmed fibroadenomas can be safely monitored with regular ultrasound (usually 6 to 12 monthly) to ensure they are not growing.
Surgery is generally recommended when:
- The lump is large (more than 3 cm) or growing rapidly
- The diagnosis is uncertain (the biopsy findings are not entirely typical)
- The patient prefers removal for personal reasons
- The lump causes significant anxiety despite reassurance
- There are atypical features on imaging or biopsy (phyllodes tumour cannot be excluded)
Types of excision
- Open surgical excision: A small incision is made over or near the lump and it is removed under local or general anaesthesia. Recovery is quick and scarring is minimal when the incision is well planned.
- Vacuum-assisted excision: A minimally invasive technique using a vacuum-assisted biopsy device to remove the fibroadenoma through a small puncture wound. Suitable for selected smaller lumps. Leaves minimal scarring.
If you have been told you have a fibroadenoma without any imaging or biopsy confirmation, it is worth getting a specialist assessment. The clinical diagnosis alone is not sufficient, imaging and histopathology provide certainty.