A radial scar is a growth that looks like a scar when the tissue is viewed under a microscope. It has a central core containing benign ducts. Growing out of this core are ducts and lobules that show evidence of unusual changes such as cysts and epithelial hyperplasia (overgrowth of their inner lining). Often, more than one radial scar is present. Another term for this condition is complex sclerosing lesions.
In many cases, radial scars are discovered as a result of a breast biopsy performed for some other reason. When radial scars are large enough to be picked up by a mammogram, they can look like breast cancer. Scars that are larger than 6-7 millimeters (mm) have a better chance of containing cancer cells or atypical hyperplasia (overgrowth of abnormal cells).
Biopsy is needed to tell radial scars apart from cancer. In almost all cases, doctors will remove them, since they are known to sometimes include cancer cells.
Researchers are still working to figure out if radial scars increase the risk of breast cancer. Right now, any increase is thought to be slight to moderate. Your doctor can help you understand your individual situation.