Radial scars are benign breast lesions, also referred to as complex sclerosing lesions when larger than one centimeter. Despite their name, these growths are not related to surgical or traumatic scarring. They are typically found incidentally during routine breast screening, often in women between the ages of 41 and 60. Their reported prevalence is relatively low, estimated to be between 0.1 and 2 per 1,000 screening mammograms.
Defining the Radial Scar
A radial scar is a non-cancerous proliferation of breast tissue characterized by a distinct star-like or rosette-like configuration. Pathologically, the lesion features a central core of dense, fibrous, and elastic tissue, which is surrounded by ducts and lobules that radiate outward. This intricate structure results from sclerosing ductal hyperplasia, an overgrowth of glandular tissue within the breast ducts. The exact cause remains unknown, but theories suggest they might result from a localized inflammatory reaction or chronic tissue injury followed by a slow healing process.
Histologically, the radiating ducts within the lesion may show various proliferative changes, such as epithelial hyperplasia, a mild overgrowth of cells lining the ducts. The presence of a radial scar is associated with a slightly elevated risk of developing breast cancer in the future compared to the general population.
The Malignancy Mimic
The primary challenge with a radial scar is its resemblance to invasive breast carcinoma on imaging studies. On a mammogram, the radiating pattern of the fibrous tissue causes a spiculated appearance, a classic sign often associated with malignant tumors. However, a radial scar’s center tends to be translucent or low-density, in contrast to the dense center often seen in a cancerous mass.
Because the visual distinction between a radial scar and a cancer can be difficult based on imaging alone, a tissue sample, or biopsy, is necessary for a definitive diagnosis. Even after a core needle biopsy, medical professionals remain cautious. The concern is that the biopsy may only sample the benign part of the lesion, missing a coexisting area of atypia or an occult carcinoma hidden within the complex architecture. This possibility of underestimation, where the initial benign diagnosis is later “upgraded” upon surgical removal, drives the careful management approach.
Assessing the True Cancer Risk
The chance of a benign radial scar diagnosis being upgraded to carcinoma upon subsequent surgical excision varies depending on the specific characteristics found in the initial biopsy. For radial scars diagnosed as “pure,” meaning there is no associated atypical hyperplasia or carcinoma found in the core biopsy sample, the likelihood of finding cancer upon surgical removal is quite low.
Studies tracking these pure radial scars have shown malignancy upgrade rates ranging from zero to 2.2 percent. One analysis found that only about 0.9 percent of radial scars without atypia were upgraded to invasive carcinoma upon surgical removal. However, the risk increases substantially when the initial biopsy reveals that the radial scar is associated with atypical cells, such as Atypical Ductal Hyperplasia (ADH). When atypia is present, the rate of upgrade to a carcinoma may be around 14 percent, making surgical removal a more pressing concern.
This long-term risk is estimated to be about two times greater than for women without the lesion. For individuals with multiple radial scars, the long-term risk of developing breast cancer appears to be higher than for those with a single lesion. The increased risk is thought to be partly independent of the presence of other high-risk lesions, suggesting the radial scar itself is a marker of susceptibility.
Current Management Recommendations
For many years, the standard approach was surgical excision for nearly all radial scars diagnosed on core needle biopsy, primarily to rule out the presence of a hidden carcinoma. This aggressive approach was a direct response to the risk of underestimation and the potential for a missed cancer.
However, management practices are evolving, particularly for pure radial scars without atypia that are small and exhibit clear radiologic-pathologic agreement. For these specific, low-risk cases, some centers now consider careful imaging surveillance as an alternative to immediate surgery. This shift is supported by research showing the consistently low upgrade rate for pure lesions. The decision to observe rather than excise is made on an individual basis, considering the patient’s overall health history and other risk factors.
If the radial scar is large, if there is any evidence of atypia on the core biopsy, or if the imaging and pathology findings do not fully align, surgical excision remains the preferred course of action. After the complete removal of a radial scar that is confirmed to be benign, patients typically return to routine annual mammographic screening. Additional surveillance is usually only recommended if the surgical pathology reveals an associated finding that independently increases the risk of subsequent malignancy.