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Atypical hyperplasia in a breast lump

Find out what atypical hyperplasia means in a breast lump.

What is it

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

Atypical cells means that the cells are not entirely normal. Normal cells go through quite a few changes before they become cancerous.

The cells may not necessarily become cancer cells. The cells might not change further. Or they may die off or go back to normal.

Who gets it

Atypical hyperplasia can sometimes develop as the breast changes with age. It can affect women of any age, but is more common in women over 35.

Diagnosing atypical hyperplasia

Atypical hyperplasia is usually found by chance after a routine mammogram or when tissue from a biopsy or breast surgery is examined under a microscope in the laboratory. 

Treatment for atypical hyperplasia

Your specialist may recommend a small operation to ensure all of the hyperplasia has been removed. This will then be examined in the laboratory under a microscope. 

There is no danger that any of the cells will have spread, if the cells removed are not cancer cells. But if the lump is left and it does become cancerous in the future, then there is a risk that some of the cells could break away from the lump and spread elsewhere in the body.

Follow up

Your specialist might 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 your situation. 

Does atypical hyperplasia affect the risk of breast cancer

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

Last reviewed: 
20 Sep 2017

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