by Jason Wasserman MD PhD FRCPC
May 1, 2024
Atypical lobular hyperplasia (ALH) of the breast is a benign (non-cancerous) condition characterized by an abnormal increase in the number of epithelial cells in the lobules of the breast. This condition involves cells that look different from normal cells but are not abnormal enough to be classified as cancer. Atypical lobular hyperplasia is considered a marker of increased breast cancer risk, though it is not cancerous itself.
Women diagnosed with atypical lobular hyperplasia have a higher risk of developing breast cancer in the future compared to women without this condition. The risk is estimated to be about 4 to 5 times greater than that of the general population. This increased risk affects both breasts, not just the one where atypical lobular hyperplasia was found.
The exact causes of atypical lobular hyperplasia are not fully understood, but the condition is believed to result from a combination of genetic and hormonal factors. Alterations in the cells within the breast lobules are likely influenced by estrogen, as this hormone plays a significant role in breast tissue growth and development. Genetic factors may also contribute to an individual’s susceptibility to developing this condition, especially if there is a family history of breast cancer.
Atypical lobular hyperplasia does not cause symptoms on its own, and the condition is normally discovered incidentally when tissue from the breast is examined under the microscope for other reasons.
Diagnosing atypical lobular hyperplasia can only be made after a pathologist examines breast tissue under a microscope. The tissue may be from a biopsy or a larger surgical procedure, such as a lumpectomy or resection.
When examined under the microscope, atypical lobular hyperplasia consists of abnormal cells that fill small glands within groups called lobules. The cells may be described as monomorphic, which means they are all very similar-looking. They may also be described as discohesive, which means they do not stick together like normal epithelial cells. Mitotic figures (cells dividing to create new cells) may also be seen.
E-cadherin is a protein made by most types of epithelial cells, including the cells normally found in the breast. This protein is normally found on the membrane or surface of the cell. Instructions for making the e-cadherin protein come from a gene called CDH1. The function of e-cadherin is to help neighboring epithelial cells stick together.
Before diagnosing atypical lobular hyperplasia, your pathologist may perform a test called immunohistochemistry (IHC). This test allows the pathologist to see if the abnormal cells produce e-cadherin. Cells that produce e-cadherin are called positive, while those that are not producing e-cadherin are called negative. In most cases of atypical lobular hyperplasia, the CDH1 gene has become altered which results in a loss of e-cadherin production.
Doctors wrote this article to help you read and understand your pathology report. Contact us with any questions about this article or your pathology report. Read this article for a more general introduction to the parts of a typical pathology report.