Invasive carcinoma of the breast with medullary features refers to medullary carcinoma of the breast, a type of invasive carcinoma of the breast. Breast cancer can be divided into non-invasive carcinoma, invasive specialized carcinoma, and invasive non-specialized carcinoma according to pathological staging. Among them, invasive specialized carcinoma includes papillary carcinoma, medullary carcinoma, tubular carcinoma and so on. It is common in young patients, usually a lump can be touched in one breast, with clear boundary, often solid, so it can be mistaken as fibroadenoma in clinic and image, under the microscope, we can see that this kind of cancer cells are in the form of syncytial growth, and it lacks the structure of glandular ducts, and medullary carcinoma of breast has the clinical manifestations of lumps of breast, and dimple sign can be seen if it involves ligament of Cooper, and cellulite change can be seen if lymphatic ducts are involved, and the advanced stage of medullary carcinoma has the clinical manifestations of lumps of breast, and it can have the symptoms of cellulite change because it involves fascia, lymphatic vessels. In advanced stage, “armored chest” may appear because of the involvement of fascia and pectoral muscle. The treatment methods of medullary carcinoma of breast mainly include surgery, postoperative chemotherapy, radiotherapy and targeted drug therapy, etc. The operation mode is selected according to the stage and spread range, including modified radical mastectomy and radical mastectomy. Medullary carcinoma of breast should consult regular hospitals in time and standardize treatment under doctors’ guidance.