Occasionally, patients with occult breast cancer present with swollen axillary lymph nodes or supraclavicular lymph nodes as the first symptom, but occasionally both are seen together without a substantial mass in the breast. Therefore, lymph node biopsy and further pathological and immunohistochemical examination are the necessary steps to make a definite diagnosis. The pathological diagnosis of metastatic lymph node cancer and the histological features of the lymph node metastases are partly considered to be from the breast for clinical reference; 2. It is of practical value to determine whether lymph node metastasis comes from the breast, with a specificity of 94%. Therefore, immunohistochemical testing of lymph node metastases with monoclonal antibodies can accurately determine whether the metastases are from the breast and provide a reliable basis for further treatment. Occult breast cancer has no special manifestation and it is not early stage. In female patients, metastatic cancer in axillary lymph nodes mostly comes from the breast, so we should focus on bilateral breast examination. The first symptom of metastasis to the axilla is much less common than occult breast cancer. The primary sites are lung, stomach and large intestine in men, and ovarian cancer and malignant melanoma of the skin in women. Therefore, it is essential to examine the above mentioned sites carefully to exclude metastatic cancer from these sites.