Fibroadenoma are benign tumors which are characterized by their firm and solid structure. They often develop in puberty and are therefore most commonly seen in young women. Even though fibroadenoma can appear at any age, the risk of developing one decreases with age.
Can fibroadenoma grow?
Typical for fibroadenoma is that they can be felt as smooth structures and can easily be moved under the skin. Usually the nodules reach a size of 1-3 cm (0,4 – 1,2 inches). However, larger sized nodules of even more than 5 cm (2 inches) have been observed. Fibroadenoma are usually not bothersome to patients, but in some cases, especially if they grow bigger, they can cause pain and discomfort. Not all fibroadenoma grow, but hormonal changes, such as a pregnancy may influence their behavior.
Also fibroadenoma are more comment in women, there have been few observations of fibroadenoma in men.
Different types of fibroadenoma
Fibroadenoma can be classified into three categories: simple, complex and giant/juvenile fibroadenoma.
- Simple fibroadenoma
The most common type of fibroadenoma are simple fibroadenoma. These nodules usually reach between 1-3 cm (0,4 – 1,2 inches) and are smooth and solid in their structure. It is uncommon for them to grow any further than this. Nevertheless sometimes they do so. Simple fibroadenoma do not bear an increased risk of developing breast cancer.
- Complex fibroadenoma
Complex fibroadenoma are different to simple ones when looked at under the microscope. These fibroadenoma show some cells with different features compared to normal cells, whilst cells of simple fibroadenoma look the same overall. Complex fibroadenoma are believed slightly to increase the chance of developing breast cancer.
- Giant / juvenile fibroadenoma
Like the name suggests, giant or juvenile fibroadenoma can grow to much larger sizes compared to simple nodules. These lumps can reach sizes of more than 5 cm (2 inches).
Growth of fibroadenoma
Fibroadenoma can be so small to an extent that they cannot even be felt. However, some fibroadenoma can grow to large lumps that can even cause extensive deformations of the breast.
The development of fibroadenoma is believed to be very much affected by the hormone estrogen. Thus, hormonal changes like use of the birth control pill, pregnancy and even the menstrual cycle can have an impact on a fibroadenoma’s growth. Growth is generally difficult to predict. On the other side, reduction in hormone levels, for example during the menopause, can lead to a reduction in size of the fibroadenoma.
How do fibroadenoma develop?
Fibroadenoma develop when fibrous and glandular connective tissue of the breast start to grow more rapidly than usual, consequently building up a lump of tissue within the breast.
The exact causes for fibroadenoma development are not fully understood yet. However, observations suggest that the hormone estrogen and a high sensitivity of the breast tissue to the hormone, play a relevant role in the likelihood of developing fibroadenoma.
It has been observed that fibroadenoma tend to increase in size during pregnancy and shrink during menopause, which strengthens the believe that hormonal factors are a major influencer. Menstrual cycles and breastfeeding, both of which cause hormonal fluctuations, can impact the growth of fibroadenoma. Furthermore, links between taking the birth control pill prior to the age of 20 and a higher risk of developing fibroadenoma have been observed.