Surgical treatment of occult breast cancer Occult breast cancer involving axillary lymph nodes is relatively rare, accounting for less than 1% of breast cancer cases; it was first described by Halsted in 1907; in 1909, Cameron proposed the classical surgical treatment of this type, namely ipsilateral mastectomy and axillary lymph node dissection in patients who lacked clinical evidence of a primary breast lesion but had a palpable axillary mass. The first surgical treatment for this type was proposed in 1954. It was not until 1954 that the first report of a retrospective study of 25 cases with axillary lymph node metastases of unknown primary origin appeared. Obviously, because of the rarity of occult breast cancer, its description is limited to retrospective studies with long duration of study and small number of cases, and therefore there is a lack of uniformity in the treatment of this type of breast cancer. Despite the significant improvements in the current diagnostic tools for breast cancer, the possibility of patients presenting with occult breast cancer still exists. This post will describe the initial evaluation, tests of diagnostic value, and comprehensive treatment of patients with occult breast cancer who develop axillary lymph node metastases. Clinical features and diagnostic evaluation The first thing to recognize is that most clinical and radiographic findings of lymph node enlargement are classified as benign status. However, once malignancy is suspected, the diagnosis is more challenging because tumors that may involve the axillary lymph nodes may include lymphoma and other hematologic malignancies, as well as adenocarcinomas of the breast, lung, colon, uterus, stomach, or thyroid, and squamous carcinoma of the head and neck. Detailed history taking and careful physical examination are important components of the diagnosis and management of such patients. For example, patients should be asked about their history of smoking, previous tissue biopsies or malignancies, family history of cancer, history of previous mole removal, and any weight loss or night sweats. Physical examination should include a meticulous mammogram, along with examination of the axillary, supraclavicular, and subclavicular regions and nodular masses including the pelvis and rectum (www.nccn.org). However, in occult breast cancer most present with the common initial histologic type when the axilla presents with lymph node enlargement. In conclusion, the axillary examination is often normal in patients with occult breast cancer except for the primary axillary lesion. If the initial examination considers the axillary lesion to be of mammary gland origin, mammography and bilateral axillary ultrasound should be performed. In addition, ultrasonography must be performed to assess the extent of regional lymphadenopathy in the ipsilateral axillary region including the potentially involved lymph node tissue, supraclavicular and internal breast lymph nodes. If the location of the breast lesion is still not clear with the above tests, an aspiration biopsy (fine needle aspiration or coarse needle aspiration tissue biopsy) of the enlarged axillary lymph nodes should be performed. Fine needle aspiration biopsy requires an experienced cytopathologist, and coarse needle aspiration biopsy also requires sufficient tissue for the preparation of multiple histologic sections to identify the site of the primary tumor lesion. Excisional tissue biopsy is performed only if the diagnosis is still not clear by percutaneous aspiration biopsy.