High-Risk Lesions of the Breast: Diagnosis and Management

High-risk lesions of the breast comprise a broad variety of diseases, which remain poorly understood. These lesions include atypical ductal hyperplasia, flat epithelial atypia, lobular neoplasia, papillary lesions, phyllodes tumor, radial scar, complex sclerosing lesions, and other rare entities. Diagnosis is frequently made by needle biopsy under ultrasound, stereotactic, or magnetic resonance imaging guidance as these lesions lack specific diagnostic imaging features. They are also referred to as B3 lesions, which histopathologically are lesions of unknown biological potential; that is, they are non-obligate precursors of malignancy and risk indicators with an increased possibility of developing breast cancer in any location of the same or the contralateral breast. The management of these lesions is challenging; a wide spectrum of therapeutic options are available to women to limit potential overtreatment in patients at low risk. The aim of this chapter is to provide a comprehensive overview of the different high-risk lesions. We review their characteristics with respect to histopathology and imaging phenotypes and discuss the role of the individual imaging modalities in this context. We detail the prognosis for the different high-risk lesions and current guidelines for management. We further discuss other therapeutic options for the women diagnosed with these lesions, such as chemoprevention. Finally, we discuss the strategies the multidisciplinary team may adopt to find an individually adapted and optimized treatment for each patient diagnosed with a high-risk lesion.