A change in breast tissue cells that represents an irregular pattern of cell growth is called atypical hyperplasia. Atypical ductal hyperplasia (ADH) is an irregular pattern of cell growth that occurs in the ductal cells of the breast. Atypical lobular hyperplasia (ALH) is an irregular pattern of cell growth that occurs in the lobular cells of the breast. Atypical hyperplasia is found in about 15 percent of breast biopsies performed after a finding of suspicious microcalcifications. These cells could be a precursor to ductal carcinoma in situ or invasive breast cancer. Women who have atypical hyperplasia are at an increased risk for developing breast cancer at some point in their life.

The good news is that ADH and ALH can be managed successfully. The most common intervention is a surgical biopsy to remove these cells and to exclude the presence of any cancer cells in this area. Depending on the patient’s health and other risk factors, she may be eligible for a drug called Tamoxifen, which when taken reduces a woman's risk for breast cancer by 50 percent. If you are diagnosed with atypical hyperplasia after a breast biopsy, your team will counsel you about the diagnosis and your treatment options.