Lobular tumors of the breast are a group of lesions with varying degrees of malignancy. Their degree of malignancy ranges from completely benign tumors all the way to completely malignant sarcomas. Name and Concept of Lobular Tumors Lobular tumors of the breast are a type of fibroepithelial tumor of the breast. It was first described in 1838. The tumor has a fleshy profile and contains vesicles. And leaf-like fissures are seen hence the name lobular cystic sarcoma of the breast. The benign character of the tumor was particularly emphasized, and no malignant connotation was given to distinguish it from breast cancer. Cumin and Chelills reported lobular tumors of the breast in 1927 and 1928, respectively, while Lee and Pack found malignant features. Subsequently, there has been much confusion in the literature regarding the meaning and name of this tumor. Some authors have found more than 60 different names for this disease. For example, lobulated cystic sarcoma. Pseudosarcomatoid adenoma. Adenomucinous tumor． Mixed tumor of the mammary gland． Pseudosarcoma, etc. In 1981, the WHO classification called them lobular tumors or lobular cystic sarcoma. In 2003, the new WHO classification named them as lobular tumors. They are divided into three categories: benign, junctional and malignant. It is divided into 3 subtypes: benign, junctional and malignant; the classification considers most of these tumors to be benign. And lobular cystic sarcoma has potential malignancy. Naming the tumor as lobular cystosarcoma is against the principle of tumor naming. It is easy to cause conceptual confusion.