In general, both diseases are malignant neoplastic diseases, but they have different origins and different prognoses and are not the same type of disease. Breast sarcoma mainly originates from mesodermal fibrous connective tissue, while breast cancer mainly originates from the epithelial tissue of cells. Common breast sarcomas include intramammary mesenchymal sarcoma, fibrosarcoma, angiosarcoma and lymphosarcoma. There is another type of tumor that is different from the common sarcoma, which is composed of benign epithelial component and cell-rich mesenchymal component, and is called lobulated tumor because of the fissures that often appear on its individual specimens, and can be classified as benign or malignant according to its mesenchymal component and degree of cell differentiation. Benign ones are called lobulated fibroadenoma; malignant ones are called lobulated cystic sarcoma, in which the epithelial component may show benign hyperplasia, while the mesenchymal component has obvious nuclear division and anisotropy. It is common in women over 50 years of age and presents as a breast lump, which can be large but clearly demarcated, with dilated veins visible on the skin surface. The mass is usually pushable without adhesion to the skin, except when the mass invades the pectoral muscle, which is more fixed. Axillary lymph node metastases are rare, while lung, mediastinal and bone metastases are predominant. Treatment usually involves total mastectomy of the affected side, but if there is invasion of the pectoralis fascia, it should be removed as well. The effectiveness of radiotherapy and chemotherapy is uncertain.