Lésions frontières du sein

Borderline lesions represent a group of lesions with an intermediate risk between frankly benign and malignant lesions. Their incidence is growing continuously with the development of screening, either individual or organized. They include different lesions, lobular neoplasia, and atypical ductal hyperplasia to which flat epithelial atypia has been recently added. Their definition is based on the level of the relative risk for subsequent breast cancer. Such lesions cause different problems. Their correct microscopic identification requires perfect technical management for both core needle biopsy and surgical resection and the use of strict histological criteria in order to ensure adequate reproducibility. The management of patients varies according to the type of specimen from image-guided biopsy, which usually requires additional resection and surgical excision. The goal of research is to better define each entity in order to increase reproducibility, to define relative risk more accurately so as to adapt management, and to identify new lesions associated with certain types of cancers and patients.