Architectural distortion of the breast.

Benign Causes of Architectural Distortion Radial Scars and Complex Sclerosing Lesions Both radial scars and complex sclerosing lesions result from idiopathic processes unrelated to trauma or postsurgical change. They are characterized microscopically by radiating ducts and lobules that show varying degrees of hyperplasia, adenosis, ectasia, or papillomatosis. Complex sclerosing lesions are usually larger than 1 cm and display more proliferative tissue than radial scars. Because most patients are asymptomatic and the lesions are not palpable, radial scars and complex sclerosing lesions are usually discovered as incidental findings on screening mammography. However, they pose a diagnostic challenge because they closely mimic scirrhous carcinomas. The typical mammographic appearance is a radiolucent central core with spiculated radiations, at times associated with microcalcifications (Fig. 1). On ultrasound, radial scars commonly present as a hypoechoic mass or parenchymal distortion that mimics malignancy. On MRI, the morphologic features and contrast enhancement patterns of radial scars and complex sclerosing lesions cannot reliably differentiate a benign from malignant process. There is only limited evidence supporting the rate of enhancement as a useful differentiating factor. Because of the inability to reliably differentiate radial scars and complex sclerosing lesions from carcinoma, the lesion must be biopsied and excised.