Hyperplasia and atypical hyperplasia of the breast tissue are benign (not cancer) breast conditions. They don’t cause any symptoms or pain and are usually found by chance.

Although they’re more common in women, hyperplasia and atypical hyperplasia can also affect men, but this is very rare.

What is hyperplasia?

The breasts are made up of lobules (milk-producing glands) and ducts (tubes that carry milk to the nipple), which are surrounded by glandular, fibrous and fatty tissue.

breast diagram

The lobules and ducts are lined by cells called epithelial cells. Sometimes these cells increase in number. This is called hyperplasia.

Hyperplasia can occur in the ducts (ductal hyperplasia) or the lobules (lobular hyperplasia). It can be graded as mild, moderate or florid (more extensive), according to how the cells look under the microscope.

Hyperplasia usually develops naturally as the breast changes with age. It can affect women of any age, but is more common in women over 35.

What is atypical hyperplasia?

Atypical hyperplasia is also benign. It’s when the cells in the breast increase in number and also develop an unusual pattern or shape. It can occur in the ducts (atypical ductal hyperplasia or ADH) or the lobules (atypical lobular hyperplasia or ALH).

Having atypical ductal hyperplasia has been shown to slightly increase the risk of developing breast cancer in the future.

Atypical lobular hyperplasia is a form of lobular neoplasia.

How are hyperplasia and atypical hyperplasia diagnosed?

Both hyperplasia and atypical hyperplasia are usually found by chance after a routine mammogram (breast x-ray) or when tissue from a biopsy (core biopsy) or breast surgery is examined under a microscope in the laboratory.

Find out more about mammograms and other tests.

Treatment and follow-up


Hyperplasia does not usually need any treatment or follow up.

Atypical hyperplasia

Once a diagnosis of atypical hyperplasia is confirmed following a biopsy, your specialist may recommend a small operation to ensure all of the hyperplasia has been removed.

Alternatively, a vacuum-assisted excision biopsy may be recommended. After an injection of local anaesthetic, a small cut is made in the skin. A hollow probe connected to a vacuum device, is placed through this. Using ultrasound or mammography as a guide, breast tissue is sucked through the probe by the vacuum into a collecting chamber. The biopsy device is used until the area being investigated has been removed. This may mean that an operation under a general anaesthetic can be avoided. The tissue removed is sent to the laboratory and examined under a microscope.

Your specialist may want you to have follow-up appointments. These may include clinic visits and a mammogram every one to two years. How often, and for how long, you go for follow-up appointments will depend on what happens in your local area.

What this means for you


Having hyperplasia doesn’t increase your risk of developing breast cancer. However, it’s still important to be breast aware and go back to your GP (local doctor) if you notice any changes in your breasts regardless of how soon these occur after your diagnosis of hyperplasia.

Atypical hyperplasia

If you have atypical hyperplasia, you may be worried or anxious that your risk of breast cancer is slightly increased. However, it doesn’t mean you’ll necessarily develop breast cancer

It’s important to go to your follow-up appointments and continue to be breast aware and go back to your GP (local doctor) regardless of how soon these occur after your diagnosis of atypical hyperplasia.

Last reviewed: May 2015
Next planned review begins 2018

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