Abstract: The discovery of precancerous breast lesions has increased considerably with the generalization of screening. There are several classifications, the most used is that of Tavassoli and Al (adopted by WHO) which classifies intra-lobular breast neoplasia into three grades: LIN1, LIN2, LIN3. Lobular neoplasias are considered indicators of risk of invasive cancer. Progress in immunohistochemistry, cytogenetics and molecular biology, made it possible to better understand these lesions separating lesions that can be considered as simple breast cancer risk markers (LIN 1, LIN 2, LIN 3 type I) from those that correspond to true precursors of breast cancer (LIN 3 types II and III ). The management varies according to the histological type. The early diagnosis of these lesions thanks to the screening as well as a good management could help reduce the incidence of breast cancer.