This volume provides a comprehensive review of the molecular mechanisms involved in precancerous lesions and benign and malignant breast tumors. Given the complex molecular pathways in breast cancer biology, the book simplifies these complex mechanisms and highlights the practical issues important for daily practice. Sections are structured to review breast carcinogenesis and the role of familial predisposition and stem cells in initiation and progression of breast cancer. In-depth chapters present morphologic and molecular correlations in precancerous and malignant breast lesions, while outlining highly practical issues that are in practice today in breast pathology, such as evaluation of estrogen, progesterone receptors, and HER-2.