Introduction to the Lymphatic System

Lymph: Colorless, watery fluid that travels through the lymph system and carries white blood cells called lymphocytes

Lymphocytes: White blood cell that protects the body against infection and growth of tumors

Tonsil: Two small masses of lymph tissue at the back of the throat. The tonsils make lymphocytes

Thymus Gland: An organ where lymphocytes grow and multiply. The thymus is located in the chest behind the breastbone

Spleen: An organ that makes lymphocytes, filters the blood, stores blood cells, and destroys old blood cells. It is located on the left side of the abdomen near the stomach

Lymph nodes: Small, bean-shaped structures that filter lymph and store white blood cells that help fight infection and disease. Lymph nodes are located along the network of lymph vessels found throughout the body.

Lymphatic vessels: A network of thin tubes that collect lymph from different parts of the body and return it to the bloodstream.

Bone marrow: The soft, spongy tissue in the center of large bones. Bone marrow makes white blood cells, red blood cells, and platelets

Lymph Nodes

Note: Not all lymph nodes are included in this image.

Location of involved lymph nodes for lymphoma is very important when it comes to staging. Lymph nodes are divided into two major groups:

Lymph nodes above the diaphragm
-Axillary, pectoral
-Cervical (neck) (occipital, submental, preauricular, submandibular, internal jugular
-Epitrochlear, brachial
-Hilar
-Infraclavicular lymph nodes
-Mediastinal (peritracheal, thymic region)
-Tonsils, adenoids, lingual tonsils
-Supraclavicular lymph nodes
- Waldeyer ring

Lymph nodes below the diaphragm
-Abdominal, NOS
-Femoral
- Iliac
-Inguinal
-Lower abdomen
-Mesenteric (superior mesenteric)
-Para-aortic (arotic, lateral aortic/ lateral lumbar, periarotic)
-Pelvic (iliac, paracervical, parametrial, pelvic, sacral)
-Popliteal
-Retroperitoneal
-Spleen
-Upper abdomen (celiac, splenic hilar, porta hepatis)

Updated: December 2, 2025