Lymph is an organic fluid whose composition is very similar to that of blood plasma. It is carried by a network of vessels called the lymphatic system. Definition, role, and diseases of lymph.

anatomy,lymph nodes,lymph node anatomy,lymphatic system anatomy and physiology,lymph node anatomy and physiology,lymph,lymph node,lymphatic system anatomy,lymphatic system anatomy and physiology in hindi,anatomy and physiology of large intestine,anatomy and physiology of lymphatic system in hindi,lymph vessels and lymph nodes,connection between the lymphatic and circulatory system,lymph node pathology,lymph node drainage anatomy,lymph node anatomy model

1. What is lymph?

According to the dictionary of the National Academy of Medicine, lymph is the "clear, transparent, pale yellow, alkaline liquid that circulates in the lymphatic vessels. It may be pink when it contains excessive numbers of erythrocytes or opalescent when it is rich in chylomicrons."

So lymph is a clear fluid that contains lymphocytes, a type of white blood cell that fights germs, foreign substances, and abnormal cells (such as cancer cells).

Lymph circulates in the lymphatic system and is constantly circulating. It is formed at the tissue level from plasma and white blood cells that filter from capillaries (the smallest blood vessels). Lymph is progressively collected in lymphatic capillaries, then in larger and larger lymphatic vessels that release it into the bloodstream at the level of the veins located under the collarbones.

Lymph thus circulates in the lymphatic vessels. These vessels look like veins, but their tunics are thin and they have more valves. The lymph circulates thanks to the contraction of muscles and the action of valves. It moves much more slowly than blood. The right lymphatic duct drains the lymph from the right arm, as well as the right side of the head and chest. There are chyliferous vessels in the small intestine, which are part of the lymphatic network, and their function is to collect the lipids absorbed by the intestine. This gives a milky appearance to this liquid, the chyle. The chyle cistern receives lymph from the lower limbs. Every day, about three liters of lymph enter the bloodstream.

The role of the lymph is to collect certain waste products, bacteria, and damaged cells from inside the body's tissues. This allows them to be removed from the body or destroyed. The lymph circulates in the lymphatic vessels which makes it circulate to the lymph nodes. The role of the lymph nodes is to clean the lymph and add lymphocytes to it. Lymphocytes are white blood cells found in the blood and lymph. They play an important role in immunity. There are different types of lymphocytes:

B lymphocytes, which make antibodies to fight infections;
T cells (thymocytes) that defend the body against disease and infection;
Natural killer cells attack virus-infected cells and/or abnormal cells, such as cancer cells.

Lymph nodes swell when we are sick or fighting a cold. This is because lymphocytes in the lymph nodes attack bacteria and viruses in the lymph.

The amount of lymph nodes varies from one part of the body to another. Nodes are grouped together, especially in :

the neck (cervical nodes) ;
the thorax (thoracic and mediastinal nodes)
the armpits (axillary nodes);
the abdomen (para-aortic, periaortic and mesenteric nodes)
groin (inguinal nodes).

2. What is the purpose of lymph?

Lymph has different functions in the human body.

First of all, it serves as an immune response. Indeed, in the lymphatic system, lymph plays an important role in the defense of the body. The lymphatic organs produce lymphocytes and the lymph transports them into the lymphatic network. The lymphatic network then transports antibodies and macrophages that fight against infections. The infectious agent passes through the lymph before reaching the lymph node. This is where the lymphocytes (immune cells) are concentrated, and they are responsible for destroying the pathogens.

The lymph also has the function of draining the body. Indeed, the lymphatic system eliminates all the residues that come from the metabolism of our cells. Through a system of increasingly large channels, it evacuates waste, viruses, bacteria, large proteins, and water accumulated in our tissues. This drainage contributes to the detoxification of the body.

Finally, the lymph participates in the proper functioning of the body. It ensures the transport of white blood cells, but also the circulation of nutrients and hormones essential to the body.

3. What are the diseases of the lymph?

Lymphedema

Lymphedema is a permanent increase in the volume of an arm or leg. This swelling is linked to an accumulation of lymph. It appears when the lymphatic vessels do not drain the lymph efficiently enough. It then accumulates in the tissues under the skin.

There are primary and secondary lymphedemas. The first, rarer, is linked to a malfunction of the lymphatic system during fetal life. This dysfunction is revealed more or less early in life. The malformation of the lymphatic system may be related to missing portions of the system, a lower than a normal number of lymphatic collectors, or dilation of the lymphatic vessels.

Secondary lymphedema is more common. It is related to the destruction or obstruction of a lymphatic network. This usually follows an event that can be: surgery, trauma, cancer, parasitic infection, etc. The obstruction may be due to tumor or filarial cells.

After breast cancer, it is quite common (between 5 and 28%) to develop upper extremity lymphedema. Secondary upper extremity lymphedema may be accompanied by edema of the operated breast and/or chest.

Lymphedema is not to be confused with edema. Edema of the legs usually affects both limbs. In edema, the skin is not thickened, hard, or inflamed. Edema is caused by a buildup of water, whereas lymphedema is related to a buildup of lymph in the affected limb.

Lymphoma

Cancer cells can develop in the lymphatic system. Depending on the appearance of the cancer cells, two forms of lymphoma can be distinguished: about 80% are non-Hodgkin's lymphoma (NHL) and 20% are Hodgkin's lymphoma (HL).

Lymphomas are characterized by the excessive proliferation of lymphocytes in the lymph nodes, liver, and spleen. This proliferation causes an increase in their size. One of the main symptoms is an increase in the size of the lymph nodes.

Unlike solid tumors, lymphocytes can grow throughout the body. Therefore, this cancer does not metastasize.

Hodgkin's lymphoma is quite rare. It is also one of the most treatable cancers. This cancer of the lymphatic system is characterized by the abnormal development of B lymphocytes. Their proliferation and accumulation in the lymph nodes lead to the development of a malignant tumor.

Non-Hodgkin's lymphoma is therefore the most common: it is even the fifth most common cancer in France, in terms of frequency. Non-Hodgkin's lymphoma is characterized by an abnormal and uncontrolled multiplication of lymphocytes. NHLs represent a heterogeneous group of diseases whose incidence and etiology vary according to the subtype. They occur at all ages, including children and adolescents, but their frequency increases after age 65.

4. How to treat them?

Lymphedema

There is no curative treatment for lymphedema yet. Indeed, the local lymphatic vessels are permanently affected, so the symptoms can reappear.

The different treatments put in place, therefore, have another role than to treat in the strict sense of the word. They serve to: reduce swelling of the limb, prevent infections of the affected limb, prevent reduction of mobility and reduce painful complications. These treatments also aim to prevent the negative consequences of lymphedema on professional and personal life.

The treatment measures are called "combined decongestive physiotherapy". The earlier they are implemented, the more effective they are in reducing the volume of the affected limb and relieving the overall symptoms. It is a method that is, however, quite restrictive.

These measures include:

compression of the limb with bandages or compression fabrics;
specific physical exercises performed with a physiotherapist;
Lymphatic drainage sessions performed by a specially trained physiotherapist;
Adapted physical activity.

Treatment with diuretic drugs is not used because, unlike edema which results from an accumulation of water, lymphedema results from an accumulation of lymph.

Lymphedema treatment has two distinct phases: an intensive phase and a maintenance phase in the treatment of lymphedema.

Lymphoma

Lymphoma is usually treated with chemotherapy. It treats the whole body. Sometimes radiation therapy is also given to fight the lymph nodes locally.

Surgery is not used. There are different treatment strategies for lymphoma and each is tailored to the stage of the disease.

If the disease relapses, further chemotherapy is often combined with a bone marrow transplant.

5. Who are the lymphatic specialists?

The angiologist is a doctor who specializes in diseases of the blood and lymphatic vessels. They play a central role in the diagnosis and management of lymphedema. However, in the case of cancer, therapeutic decisions are made in a multidisciplinary meeting.

6. What medical examinations concern the lymph?

There are different tests to study lymph. It can be a clinical examination of the lymph nodes, which consists of palpating the nodes to evaluate their size and consistency. Swollen lymph nodes are usually a sign of infection. Lymphocytes can also be tested by taking blood. This is to make sure that there are no abnormalities. A doctor may also perform a lymphoscintigraphy, an imaging test that shows the vessels and lymph nodes. It can be used to further a diagnosis or to confirm the lymphatic origin of a disease.

Sources :

Lymphe – Dictionnaire de l’Académie nationale de Médecine

Le système lymphatique – Société canadienne du cancer

Le cas du lymphœdème primaire – Partenaire français du Lymphœdème

Lymphe et système lymphatique – Vocabulaire médical

Cancers du sang : les lymphomes – Institut Curie

Lymphœdème – Vidal