Overview

Atypical hyperplasia is a precancerous condition that affects cells in the breast. Atypical hyperplasia describes an accumulation of abnormal cells in the milk ducts and lobules of the breast.

Atypical hyperplasia isn't cancer, but it increases the risk of breast cancer. Over the course of your lifetime, if the atypical hyperplasia cells accumulate in the milk ducts or lobules and become more abnormal, this can transition into noninvasive breast cancer (carcinoma in situ) or invasive breast cancer.

If you've been diagnosed with atypical hyperplasia, you have an increased risk of developing breast cancer in the future. For this reason, doctors often recommend intensive breast cancer screening and medications to reduce breast cancer risk.