Lymph Node Biopsy or Dissection
Will lymph nodes be sampled during my thyroid operation?
Lymph nodes are small glands throughout your body that collect any fluid, infection, or cancer cells. Each group of nodes is responsible for a particular body part. For example, groin lymph nodes are responsible for the legs and axillary (armpit) lymph nodes are responsible for the arms, upper chest, and breast. The head and neck area has a rich and organized lymphatic system with over 300 lymph nodes around the jaw and neck.
The lymph nodes in the neck are divided into separate compartments of the neck based on anatomic boundaries. Surgical resection of these lymph nodes (lymphadenectomy) should be performed in an organized manner, by removing lymph nodes from specific compartments which are documented or likely to contain metastatic cancer. This minimizes the risk of leaving cancerous cells behind. In the past, lymph nodes were removed in a manner similar to picking berries. Only lymph nodes appearing concerning for harboring metastatic disease were removed. However, it is well known that when there are obviously abnormal appearing lymph nodes that contain metastatic thyroid cancer, often the normal appearing lymph nodes also have some small amount of disease as well. Today, removal of lymph nodes is performed in a compartment oriented manner. All lymph nodes in a compartment are removed instead of picking out only the ‘concerning’ appearing lymph nodes. This minimizes the chance of recurrence in the same area.
Central and Lateral Neck Lymph Nodes
‘Central’ neck lymph nodes are those immeidately surrounding the thyroid and between the two carotid arteries. These lymph nodes are sometimes removed during thyroidectomy depending on the type of cancer. ‘Lateral’ neck lymph nodes to the outer sides of the carotid arteries and internal jugular veins. These are removed if they are found to contain metastatic thyroid cancer.
All patients having thyroid surgery should have a preoperative ultrasound of the lymph nodes (i.e. lymph node mapping) on both sides of the neck. If any lymph nodes look suspicious, an ultrasound-guided FNA biopsy of the lymph nodes may be performed prior to surgery.
If the ultrasound findings and the FNA are consistent with cancer in the lymph nodes, a neck dissection (removal of the cancerous lymph nodes and surrounding lymph nodes in that region) should be performed at the time of the thyroid surgery.
If the ultrasound and/or biopsies of the lymph nodes are not concerning for cancer, the lymph nodes likely will not be removed. However, during the operation, the lymph nodes surrounding the thyroid gland will be inspected and any abnormal lymph nodes would be removed and biopsied. If any of the lymph nodes contain cancer, a neck dissection would then be performed.
For patients having thyroid surgery for a benign condition, lymph nodes in the vicinity of the thyroid gland will be inspected but are not routinely sampled or removed.