The concept of the<unk>  is important because of the advent of the<unk>  biopsy technique, also known as a<unk>  node procedure. This technique is used in the staging of certain types of cancer to see if they have spread to any lymph nodes, since lymph node metastasis is one of the most important prognostic signs. It can also guide the surgeon to the appropriate therapy. A blue stained<unk>  in the axilla. A micrograph showing an adenocarcinoma of the breast (dark pink) in a lymph node (purple) and extending into the surrounding fat (white, chicken-wire appearance). H&E stain. There are various procedures entailing the<unk>  node detection: * Preoperative planar lymphoscintigraphy * Preoperative planar lymphoscintigraphy in conjunction with SPECT/CT single photonemission CT (SPECT) with a low-dose CT * Intraoperative visual blue dye detection * Intraoperative fluorescence detection (fluorescence image-guided surgery) * Intraoperative gamma probe/Geiger meter-detection *Preoperative or intraoperative super paramagnetic iron oxide nanoparticles injection, detection by using Sentimag instrument * Postoperative scintigraphy of main specimen with planar acquisition In everyday clinical activity, entailing<unk>  node detection and<unk>  biopsy, it is not required to include all different techniques listed above. In skilled hands and in a center with sound routines, one, two or three of the listed methods can be considered sufficient. To perform a<unk>  biopsy, the physician performs a lymphoscintigraphy, wherein a low-activity radioactive substance is injected near the tumor. The injected substance, filtered sulfur colloid, is tagged with the radionuclide technetium-99m. The injection protocols differ by doctor but the most common is a 500 μCi dose divided among 5 tuberculin syringes with 1/2 inch, 24 gauge needles. In the UK 20 megabecquerels of nanocolloid is recommended. The sulphur colloid is slightly acidic and causes minor stinging. A gentle massage of the injection sites spreads the sulphur colloid, relieving the pain and speeding up the lymph uptake. Scintigraphic imaging is usually started within 5 minutes of injection and the node appears from 5 min to 1 hour. This is usually done several hours before the actual biopsy. About 15 minutes before the biopsy the physician injects a blue dye in the same manner. Then, during the biopsy, the physician visually inspects the lymph nodes for staining and uses a gamma probe or a Geiger counter to assess which lymph nodes have taken up the radionuclide. One or several nodes may take up the dye and radioactive tracer, and these nodes are designated the<unk> s. The surgeon then removes these lymph nodes and sends them to a pathologist for rapid examination under a microscope to look for the presence of cancer. A frozen section procedure is commonly employed (which takes less than 20 minutes), so if neoplasia is detected in the lymph node a further lymph node dissection may be performed. With malignant melanoma, many pathologists eschew frozen sections for more accurate "permanent" specimen preparation due to the increased instances of false-negative with melanocytic staining. Clinical advantages There are various advantages to the<unk>  node procedure. First and foremost, it decreases lymph node dissections where unnecessary, thereby reducing the risk of lymphedema, a common complication of this procedure. Increased attention on the node(s) identified to most likely contain metastasis is also more likely to detect micro-metastasis and result in staging and treatment changes. Its main uses are in breast cancer and malignant melanoma surgery, although it has been used in other tumor types (colon cancer) with a degree of success. Other cancers which have been investigated with this technique are penile cancer, urinary bladder cancer, prostate cancer, testicular cancer and renal cell cancer. Research advantages As a bridge to translational medicine, various aspects of cancer dissemination can be studied using<unk>  node detection and ensuing<unk>  node biopsy. Tumor biology pertaining to metastatic capacity, mechanisms of dissemination, the EMT-MET-process (epithelial–mesenchymal transition) and cancer immunology are some subjects which can be more distinctly investigated. Disadvantages However, the technique is not without drawbacks, particularly when used for melanoma patients. This technique only has therapeutic value in patients with positive nodes. Failure to detect cancer cells in the<unk>  node can lead to a false negative result—there may still be cancerous cells in the lymph node basin. In addition, there is no compelling evidence that patients who have a full lymph node dissection as a result of a positive<unk>  result have improved survival compared to those who do not have a full dissection until later in their disease, when the lymph nodes can be felt by a physician. Such patients may be having an unnecessary full dissection, with the attendant risk of lymphedema.
Sentinel lymph node
Bouchard's nodes
Resection margin
Heberden's node
Osler's node
Medial supraclavicular lymph node
TNM staging system
Posterior triangle of the neck