Clinically, if only metastatic foci are found without primary foci, the malignant tumor is called primary unspecified cancer. This is a relatively rare type of malignant tumor and generally has a poor prognosis. However, there are exceptions: metastatic adenocarcinoma of the axillary lymph nodes in women, where the primary focus is usually the breast, has a relatively good prognosis. Clinicians usually give a physical examination of the breast, ultrasound and mammogram to patients with a complaint of enlarged axillary lymph nodes. If no intra-breast lesions are found, pathology of the enlarged lymph nodes is usually performed. This may include cases of metastatic adenocarcinoma of the lymph nodes. Next, MRI is performed in cases with confirmed lymph node metastases, and in 40-86% of these cases, a breast cancer lesion can be found in the ipsilateral breast. If no breast cancer lesion can be found, then it can be characterized as occult breast cancer. At this time, CT, PET-CT, etc. should be performed to further identify the primary foci or metastases. In the next examination, if metastases from other organs cannot be detected, you can be treated as stage II or stage III primary breast cancer. Surgery: Axillary lymph node dissection is performed in the axilla. There are two options for breast management, one is to perform mastectomy, and the excised breast can be clarified by pathological examination whether there is a primary focus. The second is whole breast radiotherapy, where the breast has a certain recurrence rate. The prognosis of the two treatments cannot be compared because of the lack of randomized controlled trials. If the ipsilateral breast is not disposed of, the breast recurrence rate can be more than 50%. If breast cancer lesions are found in the excised breast, adjuvant therapy can be treated as general breast cancer; if no breast cancer lesions are found, metastatic lymph nodes in the axilla can be used to understand ER, PR, Her2 and other indicators to guide chemoradiotherapy, endocrine therapy and targeted therapy.