Fibroadenoma

A fibroadenoma is a noncancerous (benign) breast lump. This smooth, round, solid tumor consists of fibrous tissue and glandular tissue that form a mass. In very rare cases, a fibroadenoma may contain breast cancer.

Fibroadenomas often shrink or go away without treatment. Your healthcare provider may watch a fibroadenoma over time to see how it changes or recommend surgery to remove it.

What are the types of fibroadenomas?

There are two main types of fibroadenomas:

• Simple fibroadenomas are the most common. They tend to be smaller. These lumps don’t increase your breast cancer risk. Under a microscope, the biopsied tissue appears uniform (the cells look the same all over).
• Complex fibroadenomas are more common in people over 35 and tend to be larger. Under a microscope, your provider may find some differences in the cells (they’re not uniform like a simple fibroadenoma). Your provider may also see calcifications or cysts on your mammogram. They may increase your risk for breast cancer slightly when compared to that of people with no breast lumps. Complex fibroadenomas occur about 15% of the time.

Other types of fibroadenomas include:

• Giant fibroadenomas, which are fibroadenomas that grow to be larger than 5 centimeters (cm).
• Juvenile fibroadenoma, a fibroadenoma that occurs in children and teenagers between the ages of 10 and 18. They’re rare.

How common are fibroadenomas?

Benign breast lumps, including fibroadenomas, are common. A fibroadenoma is the most common type of benign breast lump. They happen most often when you’re between ages 15 and 35. Up to 10% of people assigned female at birth (AFAB) will have a fibroadenoma at some point in their lives.