What are they?

Fibroadenomas are the most common benign solid lumps. They are caused by an overgrowth of the normal breast tissue in one of the lobules of the breast, probably due to increased sensitivity to oestrogen.

Who gets them?

They are found most commonly as a non tender mobile lump (breast mouse) in young women in their 20s and 30s.

How do they behave?

The natural behaviour of fibroadenomas has been studied. They gradually increase in size up to to 1 - 3cm over a period of about 5 years.After this growth period they can remain the same size for many years or gradually become smaller. Occasionally one may continue to grow until it is more than 5cm in size to form a giant fibroadenoma.

They can also develop later in life.

How are they discovered?

Usually found when a lump is noticed in the breast.

Breast screening often finds fibroadenomas that cannot be felt either because they are very small or because they are situated deep within the breast tissue.

The diagnosis can usually be made on clinical exam, ultrasound and needle biopsy.

View case example

How are they treated?

In the past all breast lumps were excised. We now know that it is safe to manage some fibroadenomas conservatively as long as the diagnosis has been made accurately using the triple assessment principles.

  1. Reassurance and follow-up with clinical and ultrasound.
  2. Excision

Reasons to excise the lump:

If the diagnosis is in doubt. If triple assessment does not provided a definite diagnosis then I will recommend excision of the lump.

For peace of mind. Many people have heard stories about breast lumps that were left for some time and eventually turned out to be cancer . They may prefer to have the lump removed and not have to worry about checking on it all the time.

To relieve symptoms such as pain. Occasionally a fibroadenoma may be quite sore whin it is bumped.

The operation is performed as a day case procedure and takes 40 - 60 minutes in theatre.

Phylloides Tumour:

This is an unusual lump that has some similarities to a fibroadenoma but behaves differently in that it continues to grow. The pattern of growth varies from very slow to being quite aggressive. The diagnosis can be missed on a needle biopsy as the features are very similar to a benign fibroadenoma. The correct diagnosis is often only made when the lump is finally excised because it has continued to increase in size over a period of time and the pathologist is now able to examine the whole lump.

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