The lymph is a light-yellow fluid that contains the so-called lymph plasma and certain white blood cells known as the lymphocytes. The lymphatic fluid is consisted of interstitial fluid, protein, fatty acid and chyle. Chyle is the fats collected from digestive system. The lymph or lymphatic fluid flows through the lymphatic vessels that is fine tubular structure spreads around viscera, muscles and subcutaneous tissue. The lymphatic fluid flows through the vessels and content of lymph fluid are filtered at lymph node. The lymph node act like a station that slows down the flow of lymph to distal lymphatic channels. The lymph nodes filter toxins, bacteria and viruses that helps to purify the lymph. The ganglia thus extracts, pathogenic germs and toxic substances. Obstruction of lymph flow through lymph node causes accumulation of lymphatic fluid in proximal lymphatic vessels known as lymphedema.
The collection of toxins and bacteria within lymph node in few cases causes infection and inflammation of lymph node. The lymph node inflammation often follows scarring of lymph node. Scarred lymph node blocks the flow of lymphatic fluid forward. Such blockade of flow of lymph through the node causes swelling of proximal lymph vessels. Following blockade of lymph node lymph fluid extrudes into surrounding tissue resulting in tissue swelling. Such tissue swelling caused by swollen lymphatic vessels and extruded lymphatic fluid is known as lymphedema. Lymphedema resulting in tissue swelling observed mostly in upper and lower extremities. The swelling is visible and palpable and in few cases become inflamed that causes mild to severe pain. Lymphedema is common following surgical removal of lymph node in patient suffering with cancer of chronic infection. Lymphedema is also observed in head, neck, trunk, and genitals.
What Causes Lymphedema?
Lymphedema can be due to many different causes. In the majority of cases, it is due to the obstruction of the lymphatic vessels at the lymph node. The obstruction of forward flow of lymphatic fluid within lymphatic vessels increases pressure within lymph vessels. The increase pressure causes swelling of vessels and extrudes clear fluid in to surrounding soft tissue. The condition is known as obliteration of lymphatic vessels and lymphedema. The swelling of tissue underneath the skin is in few causes inflammation of surrounding tissue and pain.
What is Primary Lymphedema
Primary lymphedema is caused by congenital narrowing as well as blockage of lymph vessels and lymph node. The condition is inherited and known as hereditary lymphedema. The symptoms are rarely observed in child born with abnormalities in lymphatic system. Hereditary lymphedema often affects the legs, specifically on both sides of the calf. They appear more strongly during the warm seasons and, in the case of women, also during menstruation. Primary lymphedema is classified in to following two conditions.
Type I Hereditary Lymphedema (Milroy’s Disease) – Congenital alteration of the lymphatic system, it is evidenced before being born; it is not associated with other discomforts.
Type II Hereditary Lymphedema (Meige’s Disease) – The condition is observed in several family members and thought to be genetic in origin. Meige’s disease usually appears at puberty. The condition affects younger women more than young men. Meige’s disease is associated with other symptoms such as dwarfism, overweight and mental disability. Individual random lymphedema is caused by hereditary alteration of the lymphatic vessels. In rare cases, it is due to the alteration of the composition of the lymphatic fluid. This primary lymphedema occurs between 15 and 20 years. In 50% of cases, lymphedema is limited to one leg. The swelling initially appears in ankle and then spreads to leg above and below knee joint. However, in every two cases, lymphedema also appears in the other leg after months or years. In this case, too, it affects women more than men.
What is Secondary Lymphedema
An acquired or secondary lymphedema always has its origin in another disease. The causes are varied. Surgical interventions are the most frequent of a secondary lymphedema. Thus, after a breast cancer surgery in which axillary lymph nodes have been removed, it is very common to see lymphedema in the arms. Lymphedema is seen in several patients following removal of breast cancer and axillary lymph node.
In these cases, overweight can also have a negative impact: for example, after treatment for breast cancer, overweight increases the risk of developing secondary lymphedema for a lifetime by between 40 and 60%. In principle, any lesion, sprain or scar of different origin can trigger a secondary lymphedema. Parasites can also cause inflammatory lymphedemas that is spread in scrotum, upper and lower extremities. The filariasis is the disease cause by parasite. The filariasis affects the lymph vessels of scrotum as well as extremities. Filariasis is a rare disease causes inflammation of the lymphatic pathways. The disease is also known as lymphangitis. The lymphedema is also observed when function of lymph node is blocked by spread of cancer in groin and axilla. Malignant lymph node diseases such as Hodgkin’s lymphoma or certain types of leukemia also causes obstruction of flow of lymph through lymphatic vessels and lymph node. A lymphedema may also arise from the obstructive diseases of venous system. The accumulation of serous fluid and lymph in subcutaneous tissue secondary to obstruction of venous fluid is known as phlebolymphedema.
The causes of lymphedema can be either primary if it is acquired at the time of birth or secondary when it is caused by diseases resulting in blockade of flow of lymphatic fluid. In less frequent cases, lymphedema is due to an alteration in the composition of the lymph. Another possible trigger can be scarring of lymph node secondary to infection or lymph node damage by surrounding cancer. The lymph node damage is also caused by radiation and surgery. In few cases lymph node is removed to prevent spread of cancer that result in obstruction of lymph flow and lymphedema.
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NIH: US National Library of Medicine
NIH: National center for Advancing Translational Sciences. Genetic and Rare disease information center.
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