Radial Scar/Complex Sclerosing Lesion

Radial scar (RS) is a pseudo-infiltrative lesion characterized by a fibroelastotic core with entrapped ducts and surrounding radiating ducts and lobules demonstrating a range of epithelial hyperplasia.[20] The term "radial scar" is used for lesions < 1cm and the term "complex sclerosing" lesion is used for lesions > 1 cm in size. The epithelial component can display a variety of atypia and may represent a nidus for development of ductal carcinoma in situ. RS are commonly seen incidentally in pathology specimens obtained for other reasons, but can also be seen as non-palpable lesions detected on screening mammography.

On mammography RS are commonly seen as an area of focal architectural distortion, and are better seen in one projection, without any discernable central mass or overlying skin retraction.[21] The lesion has a "black star" appearance with long thin spicules radiating from a central radiolucent area (Figure 2A). Ultrasound may not always detect RS, but can show a poorly defined hypoechoic area, or an irregular hypoechoic mass with ill-defined, spiculated margins and varying degrees of posterior shadowing.[22] There are no specific sonographic features that distinguish RS from breast cancer. MRI typically demonstrates a focal low signal area of architectural distortion on T1- and T2-weighted images with enhancement ranging from none/minimal to intense enhancement with, at times Type-III kinetics (Figure 2b).[23] Accumulating evidence indicates an association with atypia and/or malignancy and suggests that it is an independent risk factor for development of carcinoma in either breast. Therefore, excision is recommended following a diagnosis of radial scar on core needle biopsy.[20,21]