Atypical hyperplasia of the breast


Atypical hyperplasia is a precancerous condition affecting breast cells, characterized by the presence of abnormal cells in the milk ducts and lobules. While not cancer itself, atypical hyperplasia heightens the risk of developing breast cancer. If these abnormal cells continue to accumulate and become more irregular over time, there is a potential progression to noninvasive breast cancer (carcinoma in situ) or invasive breast cancer.

Individuals diagnosed with atypical hyperplasia face an elevated risk of future breast cancer development. As a preventive measure, healthcare professionals often recommend rigorous breast cancer screening and may prescribe medications aimed at reducing the risk of breast cancer.


Typically, atypical hyperplasia does not manifest specific symptoms, making it challenging to identify without medical examination. If any concerns or signs trouble you, it is advisable to schedule an appointment with your doctor promptly. This condition is often detected during a breast biopsy conducted to investigate anomalies found on mammograms or ultrasounds. Occasionally, atypical hyperplasia is uncovered during a biopsy performed to explore various breast concerns, such as lumps or nipple discharge.


The development of atypical hyperplasia in the breast is not fully understood. This condition arises when there are abnormalities in the number, size, shape, growth pattern, and appearance of breast cells. The specific type of atypical hyperplasia is determined by the appearance of the abnormal cells, which can manifest as either atypical ductal hyperplasia within the breast ducts or atypical lobular hyperplasia within the breast lobules.

Atypical hyperplasia is viewed as a component of the complex cellular transitions that could potentially lead to the onset of breast cancer. The progression to breast cancer typically involves the following stages:

  • Hyperplasia: The disruption of normal cell development and growth results in an overproduction of normal-looking cells, a condition known as hyperplasia.
  • Atypical hyperplasia: Excess cells accumulate and start to exhibit abnormal characteristics.
  • Noninvasive (in situ) cancer: The abnormal cells continue to progress in appearance and multiply, evolving into in situ cancer. In this stage, cancer cells remain confined to the milk ducts.
  • Invasive cancer: The abnormal cells further accumulate within the duct, continue to multiply, and transform into cancer cells. Invasive cancer is characterized by the invasion of surrounding tissues, blood vessels, or lymph channels.