Radial scars (RS) are benign, tumor-like lesions which are most commonly an incidental finding during mammography. When they are greater than 1 cm in diameter, they are referred to as complex sclerosing lesions. The recent widespread use of imaging techniques such as mammography has led to the identification of features characteristic of this lesion.
In mammography, RS present as characteristically spiculated in appearance, similar to a carcinoma. However, these have a translucent and low-density centre rather than a highly dense central mass. These lesions lead to the distortion of glandular tissue which may make it challenging to differentiate from low-grade carcinoma in histological sections. Furthermore, glandular tissue entrapped within RS may contain a distribution (focal or dispersed) of atypical or malignant cells.
Due to the similarity between RS and carcinoma on imaging or mammography, it is recommended that post-mammographic evaluation be done in order to diagnose the lesion and to exclude any possibility of malignancy. Most commonly, imaging-guided core needle biopsy (CNB) is the technique of choice. This is advised in spite of the finding of benign pathologic changes in most CNB specimens.
When a woman presents with RS after an excisional biopsy or mastectomy, routine follow-up is the appropriate management. However, whether CNB is the optimal clinical approach for these patients is disputed. The majority of RS diagnosed in a CNB sample are actually surgically excised, regardless of the size and other features of the lesion. Not all detected RS warrant such action and this approach to management may be controversial, in light of the fact that RS are commonly small (5 mm or less) and were found incidentally during radiological imaging for unrelated indications.
The surgical upgrade from RS to a high-risk (malignant) lesion can be 0-12%. However, this can only be determined as certain if the entire lesion is available for histopathologic examination. Thus, the inadequate sampling by CNB may pose a problem resulting in underestimation of the likelihood of the presence of carcinoma in the surgical excision sample.
A change in CNB device could partially resolve this concern. In other studies, the rate of underestimation of samples is higher when a 14-gauge automated spring-loaded device is used rather than a larger-gauge vacuum-assisted device.
Following mammography, the use of ultrasound (US)-guided 14-gauge CNB to evaluate non-palpable lesions has yielded a low underestimation rate of upgrade to malignancy and/or atypia, as confirmed on histological examination. Further clinical improvements are required, but this technique may allow for a reduction in underestimation. In case the CNB reveals no high-risk lesions, the probability of finding cancer at excision is markedly reduced, and the patients involved will not require a surgical excision as part of their follow-up. Surgical removal with an adequate margin, however, is highly recommended following the detection of palpable RS and those greater than 1 cm, due to the higher risk of malignancy associated with larger RS and the potential for sampling error in these lesions. This appears to be most likely in older patients, as it is noted that older age is positively associated with pathologic upgrade to changes reflecting atypia and malignancy.
Unfortunately performing a CNB in all RS patients would be difficult to implement. It would require a great deal of time, expense, effort, and cause discomfort for patients, because RS are often challenging to image. On the other hand, the only alternative strategy would be the immediate surgical excision of all RS diagnosed through mammography.