The pathologist is involved at various steps in the management of a patient with breast cancer and in the therapeutic decision. First, the pathologist confirms a diagnosis of malignancy on cytology specimens, microbiopsies and surgical specimens. During the surgery, through the frozen section, the pathologist specifies the surgical limits and collects specimens for research purposes. Then the pathologist evaluates the parameters needed to establish the final diagnosis, the prognosis and the identification of predictive factors, using ancillary techniques such as immunohistochemistry, in situ hybridization or molecular techniques. Mandatory elements to be included in the final pathological report are size, histological type, SBR grade modified by Elston and Ellis, the presence or absence of vascular or lymphatic peritumoral emboli (prognostic parameters), the status of resection margins (local relapse risk) and the status of hormonal receptor and HER2 (predictive parameters).