[Breast cancer: the interest of pathological classification]

The breast pathology includes a large array of entities for which macroscopic and microscopic analysis remains fundamental. Tissue and cell morphology allows in most cases the distinction between benign or malignant tumours and therefore provides the clinicians with essential information for the therapeutic strategy. In the Pathology laboratory, immunohistochemistry and molecular biology have improved the specificity of the diagnosis and have introduced new prognostic and predictive markers for tumour management. The last edition of the WHO classification, released in 2003, distinguishes 21 varieties of invasive carcinoma and 2 categories of intraepithelial neoplasia based on the morphology and immunohistochemical profile. Other diseases can affect the breast, although much less frequently, such as Paget's disease of the nipple, phyllode tumours, sarcomas, lymphomas... These diseases will not be reviewed here.