Sentinal Node Biopsy / Node Disection

Sentinel Node Biopsy is a procedure commonly performed as part of the management of breast cancer and melanoma. The Sentinel node is the first lymph node which receives drainage from lymphatics within a specific region. By removing the sentinel node, one can determine whether cancer cells have spread to the node itself. This will help with predicting long term outcome and will guide further management. The sentinel node can be located by injecting radioisotope near or adjacent to the tumour site prior to surgery. Thereafter, a lymphoscintiscan is often performed to map out the site/s and number of sentinel nodes. In the context of breast cancer, this is usually in the axilla(armpit). For melanoma, the sentinel node may be located in the neck, above the clavicle (collar bone), axilla or groin, depending on the site of the initial lesion and the lymphatic drainage. Blue dye may also be injected during surgery to assist with sentinel node identification. The sentinel node is then removed and sent to the laboratory for microscopic analysis to check on whether there are tumour cells present.

It is important that the sentinel node biopsy operation is performed by a surgeon who is specifically trained in the technique and regularly performs the procedure. This ensures the highest chance of success in finding the true sentinel node/s so that an accurate result can be obtained.

If a sentinel node is involved with tumour cells, further surgery is often necessary to remove the rest of the lymph nodes in the same nodal group to ensure that any tumour cells remaining are adequately removed from that region. This operation is variably known as Nodal Dissection or Clearance, Block Dissection, Neck Dissection, Axillary Dissection or Axillary Clearance and Groin Dissection, depending on the site of the nodal group. The surgery is performed with meticulous attention in ensuring that the nodes and lymphatics are completely and cleanly removed (“en-bloc resection”), so that there is no tumour spillage into surrounding tissue. A drain is inserted after a nodal dissection to drain seroma fluid which is naturally produced by the body and secreted into the tissue space. This drain is removed once the drainage slows down which can take up to 1 – 2 weeks after surgery (sometimes longer). Once the drain is removed, it is not uncommon for the body to continue to produce seroma fluid within the operative site. This is usually reabsorbed over time but if a large volume is produced, it may result in a visible swelling that becomes uncomfortable. This usually requires needle aspiration which may be repeated as often as necessary until resolution of the collection.

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