Sentinel (Blue) Lymph Node Biopsy

What It Is

Breast cancer can spread to the nearby tissue in the underarms (axillary). This tissue is known as lymph nodes. The first node in the group is known as a sentinel node. If no cancer is found in the first node, the cancer has probably not spread to other nodes in the area. If cancer cells are present in the first node, the lymph nodes in the affected area may require removal. Removing the nodes from the areas is known as axillary lymph node dissection.


What to Expect

Only the first lymph node in a group is removed during the biopsy. A specialist will look at the node to see if there are any cancer cells.

To find the node, a special blue dye or radioactive substance is injected. These will identify the first lymph node. This will make it easier for the doctor to find the node. This is called lymphoscintigraphy, or sentinel lymph node mapping.

The doctor will inject the radioactive material before surgery (preoperative) and the blue dye during surgery (intraoperative).

Preoperative Mapping

1. A special substance with a small amount of radioactivity is injected where the tumor is.
2. This flows toward the lymph nodes and allows an X-ray image of the lymph nodes.
3. The doctor uses a radiation detector during surgery to pinpoint the lymph node that has the highest radiation counts.

The radiation in the injection is no more than what is produced by chest X-rays or mammograms. No negative reactions have been reported when using this method.

Intraoperative Mapping

1. During the operation, the patient is injected with a blue dye around the nipple or breast cancer site.
2. The lymphatic channels then absorb the dye.
3. A small cut is made in the armpit to search for the sentinel node or nodes. Blue-stained lymphatic channels are identified and followed to the sentinel node or nodes.
4. One or more sentinel lymph nodes are removed and looked at under a microscope. Blue nodes, or "hot" nodes (nodes with high radioactive counts), are removed and called sentinel nodes.


Possible Side Effects

  • Discomfort. Lymph node biopsy surgery always produces some discomfort for about a week after the operation. Swelling or fluid builds up under the incision and can remain for several weeks.
  • Infection. Infection is uncommon and can develop up to seven days later.
  • Lymphedema. The most serious side effect is swelling in the arm, known as lymphedema. The risk of lymphedema with a sentinel lymph node biopsy is universal.
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