A radial scar is a form of sclerosing duct hyperplasia. There is typically no solid, dense central tumor corresponding to the size of the spicules. But, often there are translucent, circular, or oval regions in the center of the radiating structure which gives the radial scar a characteristic 'star-like' appearance. Radial scars may indicate a disturbance in the breast tissue and more specifically between the stromal (supportive)and functional elements (lobules, ducts, etc), that can lead to the formation of scar tissue, or possibly to cancer.
A finding of a radial scar is thought to be an increased risk factor for breast cancer. Women with a radial scar are thought to be at higher risk for breast cancer development, ranging from approximately 8% to 30%.
At mammography they may be detected as a kind of star-shaped feature with spiculated contours and no or little central mass. They are not detectable using ultrasound, and they are usually confirmed during biopsy.
The image below is a mammogram of a radial scar.
The spiculated, star-like configuration of the radial scar can resemble tubular carcinoma, so to establish a differential diagnosis, a biopsy is taken examined under a microscope. Typically one of two stains is applied to the tissue: either hematoxylin-eosin or immunohisotchemical actin. A finding of healthy myoepithelial cells in the histological workup exludes the diagnosis of tubular carcinoma.
The images below are histology slides of breast tissue, and show benign ducts within a sclerotic stroma, thus ruling out the possibility of tubular carcinoma. The breast tissue in both of these images has much thicker collagen (fibrous tissue ), than average, and would in fact feel much harder too the touch than normal.
Hematoxylin-Eosin is a type of stain, applied to the tissue, which makes things look a certain way under the microscope.
The second image uses a stain called 'staining-actin', often used to find smooth muscle tissue (actin).The actin stain shows the smooth muscle as the darker-brown color where muscle cells are lining the outside of ducts (tubules).
In both images above, the absence of any kind of abnormality affecting the epithelial lining of the tubules rules out tubular carcinoma, and confirms the diagnosis of radial scar.
There is some danger of 'false negative' finding if the biopsy is done with very small samples, such as by fine needle aspiration or a needle core biopsy. In it not uncommon for a radial scar or complex sclerosing lesion to contain small amounts of malignant breast cancer cells. An excisional biopsy is usually recommended.
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