The lymphatic system is a series of ducts that carry fluid known as interstitial fluid throughout the body. The interstitial fluid contains large-cell proteins, which are used for the nourishment of the body’s cells. In a healthy body, the interstitial fluid passes through the duct network and out through the thoracic duct where it joins with the bloodstream to be recirculated. Lymphedema is a term that includes a number of disorders that all result in the failure of the interstitial fluid to properly circulate. It instead sits within the lymphatic ducts and causes a great deal of pain and tissue swelling. Congenital lymphedema is the form of lymphedema that is present from birth as a result of a developmental defect. The arterial capillaries that line the lymphatic ducts are not sufficiently developed to create the high pressure needed to force the interstitial fluid continuously through the lymphatic system.
Infection-related lymphedema occurs most commonly in tropical and sub-tropical parts of the world and may be contracted by unsanitary living conditions and insect or animal bites. Acute streptococcal or staphylococcal infections are typically the culprits. Staphylococcus causes the arterial capillaries of the lymphatic system to swell and constrict. This results in the interstitial fluid pressing against and sometimes bursting the walls of the lymphatic ducts. Conversely, streptococcus scars the walls of the arterial capillaries, paralyzing them. They are then unable to push the interstitial fluid through, and it pools.
Lymphedema distichiasis only causes the legs to swell. In addition, cysts forming on the spine and a double row of eyelashes are common. As opposed to congenital lymphedema, lymphedema distichiasis is hereditary. It’s caused by a mutation of the FOXC2 gene, wherein the lymphatic ducts in the legs become too large and overdeveloped. As such, interstitial fluid cannot be forced out of them.