Radial scar

by Kimberly Wood, MD MSc FRCPC
March 13, 2022

What is a radial scar in the breast?

A radial scar is a non-cancerous growth that develops in the breast when there is an increase in the number of glands and ducts surrounding an area of altered connective tissue called a scar. Although non-cancerous, it is associated with a small increased risk of developing breast cancer when compared to women without radial scars. Another name for a radial scar is a complex sclerosing lesion.

How do pathologists make the diagnosis of radial scar in the breast?

A radial scar can be diagnosed after a small sample of tissue is removed in a procedure called a biopsy. The diagnosis can also be made after a larger area of tissue is removed in a procedure called an excision or resection.

For many patients, a radial scar is discovered incidentally after tissue is removed from the breast for another reason. However, some radial scars can be seen on screening mammography or ultrasound, especially when they are greater than 1 cm in size. Because a radial scar can look very similar to breast cancer on mammography or ultrasound, a biopsy is performed to confirm the diagnosis.

What does a radial scar look like under the microscope?

When examined under the microscope, a radial scar is made up of abnormal connective tissue that pathologists describe as fibrosis. The abnormal connective tissue is sometimes described as showing elastosis or elastotic because it contains numerous elastic fibers. Small irregularly shaped ducts and glands are often seen trapped within the area of fibrosis. Other non-cancerous changes that are often seen in the tissue surrounding a radial scar include usual ductal hyperplasia (UDH), cysts, and apocrine metaplasia.