Definition and Overview
A lymph node is a component of the immune system that serves as a filter to protect the body against harmful substances. They can be found all over the body and in healthy people, they are not usually noticeable or palpable. An enlarged or swollen lymph node typically suggests the presence of a pathologic condition.
A lymph node biopsy is a procedure wherein an entire lymph node or a part of it is extracted and sent to the laboratory to diagnose certain conditions, grade cancer, or to determine if cancer has metastasised to other parts of the body.
Who Should Undergo and Expected Results
Lymph node biopsy is recommended for patients with:
Enlarged lymph nodes - Enlarged lymph nodes typically suggest the presence of an underlying disease, such as an infection or cancer. A biopsy is often recommended particularly if a myriad of other non-specific symptoms accompany lymph node enlargement, such as fever, cough, generalised weakness, and weight loss.
Cancer - Lymph node biopsy plays a major role both in the diagnosis and staging of cancer, helping physicians determine the proper course of therapy for cancer patients. In cases of breast cancer, sentinel lymph node biopsy can be performed to determine if the disease has spread to the lymphatics.
How is the Procedure Performed?
A lymph node biopsy is usually a minor surgical procedure performed on an outpatient basis. There are different techniques used for this procedure depending on the severity of the case and the part of the body where the lymph node is taken.
A needle biopsy is the simplest form and uses a syringe with a needle at the end to aspirate cells from the lymph node. This can be performed on both small and large nodes that lie in deep areas, such as the chest. In these cases, some form of imaging technology (such as a CT scan) may be needed as a guide for the physician performing the procedure. The sample is then fixed on a glass slide for review under a microscope.
Compared to a needle biopsy, which only takes samples of a lymph node, an open biopsy involves the removal of the entire lymph node. This technique is ideal for those that are in superficial locations, such as the neck. Because the node is usually accessible, the procedure is typically performed under local anesthesia. A small incision is made over the lymph node so it can be dissected from surrounding tissues and removed. The biopsy site is then closed with sutures and bandage is applied over the wound.
Sentinel lymph node biopsy, on the other hand, is a specialised kind of lymph node biopsy performed in certain cancer patients. A dye or a radioactive tracer is injected into the cancer site to determine and remove the lymph nodes that is closest to the cancer. The node is then sent to a laboratory for further examination.
For patients undergoing surgery for a malignancy, such as lung cancer, lymph nodes near the tumor may also be excised and sent for biopsy to determine the stage of cancer and subsequent treatment (for example, chemotherapy or radiotherapy).
Various kinds of examinations can be performed for the harvested lymph nodes, which are fixed and examined under a microscope to check for specific histopathologic features. For undetermined malignancies, certain immunohistochemical studies can be performed to diagnose the specific type of cancer the patient has. Other studies, such as immunophenotyping and in situ hybridization tests, may also be performed to distinguish cancer subtypes, such as in the case of lymphoma.
Possible Risks and Complications
Minimal risks are associated with lymph node biopsies. Slight swelling and pain around the biopsy site are normal and usually resolve on their own after a few days. Bleeding is another risk, especially if the lymph nodes are located near blood vessels. When performed properly, a lymph node biopsy will result only in minimal bleeding that stops spontaneously after pressure is applied. Numbness may also occur, especially if the lymph nodes lie close to a nerve but sensation usually returns after several weeks. Infection is another risk but is not commonly encountered. Regular dressing and antibiotic treatment are used to manage these infections.
Burstein HJ, et al. (2011). Malignant tumors of the breast. In VT DeVita Jr et al., eds., DeVita, Hellman and Rosenberg's Cancer: Principles and Practice of Oncology, 9th ed., vol. 3, pp. 1401-1446. Philadelphia: Lippincott Williams and Wilkins.
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.