How Are Fibroadenomas Formed?

You've found a lump in your breast. Now what? While your mind may jump to the worst case scenario — breast cancer — there are a variety of other less serious causes, including a fibroadenoma.

In addition to his work in clinical practice in Santa Monica, California, Dr. Trevan Fischer is involved in clinical trials at the John Wayne Cancer Institute and serves as an assistant program director of its Complex General Surgical Oncology Fellowship program. Whether you need surgical treatment for cancer or diagnosis of a benign breast issue like a fibroadenoma, Dr. Fischer and his expert staff offer state-of-the-art personalized care.

What is a fibroadenoma?

Typically painless, a fibroadenoma is a noncancerous lump in the breast that can move around under the skin and may feel like a marble. It’s usually relatively small at just 1-2 centimeters and almost always less than 5 centimeters in diameter. Approximately 10% of women experience a fibroadenoma, though frequently they don’t realize it.

Fibroadenoma formation

No one knows what causes the creation of a fibroadenoma. Since it usually occurs in women between the ages of 15-35 and those who are pregnant or breastfeeding, experts speculate it may occur due to changing hormone levels.

Breasts get their shape and size from glandular, fibrous, and fatty tissue. Within this tissue are milk-producing glands known as lobules, as well as ducts that transport milk to the nipples. A fibroadenoma begins as an excess lobule that then gets overgrown by glandular tissue and ducts, ultimately resulting in a solid lump. 

Fibroadenomas can form into four different types:

Simple fibroadenoma

A simple fibroadenoma is about 1-3 centimeters and appears the same all over when examined under a microscope.

Complex fibroadenoma

Complex fibroadenoma may have rapidly growing cells and therefore be larger. It’s more common in older women.

Juvenile fibroadenoma

When a girl between the ages of 10-18 finds a lump in her breast, it’s most likely a juvenile fibroadenoma. While it can increase in size, it eventually shrinks and often disappears.

Giant fibroadenoma

This type of fibroadenoma can reach 2 inches or more and may need to be removed.

Fibroadenoma diagnosis and treatment

Diagnosis of a fibroadenoma is typically done through examination and diagnostic imaging like an ultrasound or mammogram. In some cases, Dr. Fischer may do a biopsy to study the tissue in more detail.

For many women, either no treatment is necessary or a wait-and-see approach is taken to determine whether the fibroadenoma shrinks or grows. For those whose fibroadenoma increases in size or don’t have a definitive diagnosis, removal may be the best option.

If you've detected a lump in your breast, getting a proper diagnosis is key. Call our office at 310-504-2548 or click to book an appointment online today.