The Lymphatic System The lymphatic system is similar to the blood system and has just as many vessels - but they contain lymph, which is clear and so cannot be seen (unless a suitable dye is injected). The lymphatics differ from the blood system in that the blood continually circulates through each part of the body while the lymph just drains from each part. Lymphatics drain away the excess protein and water which continually escape from the blood in small amounts, plus some substances made in the tissues, and any foreign substances which enter them. Lymphatics start, in almost every tissue, as many tiny vessels which gradually join together into bigger ones. Lymph is pumped into and along these vessels by the movements of adjacent muscles and by the contractions of the walls of the larger lymphatics. This pumping is aided by many valves inside the vessels. Finally the lymphatic system empties into the blood (largely in the lower neck). On its way along the lymphatics, the lymph is filtered in the lymph nodes (lymph glands). These remove foreign matter (e.g. bacteria) and start any necessary immune reactions. Oedema (Edema) The lymphatics help to remove the excess fluid and protein which enters the tissues from damaged blood vessels, in any inflammation (e.g. after a burn, or other injury). If they cannot remove it all, the part swells (oedema, edema). However this swelling is usually only temporary, because the tissues heal and the blood vessels no longer leak excessively. In an acute injury, e.g. a sprained ankle, the lymphatics are essentially normal. Although there is initial swelling, this is gradually removed over days to weeks. The overload is only temporary although, depending on the severity of the injury, some fibrosis will occur. This may remain for months or even permanently. Lymphoedema (Lymphedema) However if the lymphatic system is damaged or blocked, protein continues to enter the tissues from the blood capillaries in the normal way, and a build-up occurs in the tissues the lymphatics should be draining. The accumulation of protein in the tissues causes excess fluid to enter them and the tissues to swell. The swelling decreases the oxygenation of the tissues, interferes with their normal functioning, and makes them heal more slowly than normal. To some extent, the protein is also removed by some of the cells in the tissues (e.g. the macrophages). These assist the lymphatic system and can partly take over its role if it is blocked. However in lymphoedema, the chronic excess protein causes these cells also to cease to function. The excess protein also acts as a stimulus for chronic inflammation. One of the results of this is the formation of much excess fibrous tissue. The chronic inflammation causes more blood capillaries to form and to be dilated. This makes the limb feel hot. This heat, combined with the stagnant protein provides a perfect site for bacterial growth (Secondary Acute Inflammation, S.A.I. or dermato-lymphangio-adenitis, D.L.A.). The patient may be very ill, with constant infections, and need hospitalisation. Fungal infections are also very frequent, and are often difficult to clear up. These infections, themselves, place greater loads on the lymphatics, and so worsen the lymphoedema. Any infection or other inflammation (e.g. after injury, sunburn, etc.) makes the lymphoedema worse. If the swelling is rapid (e.g. after an operation), it can cause great pain. This is because the tissues are being torn apart. Adjacent areas, which are receiving excess lymph diverted from the blocked region, also often ache (e.g. the shoulder adjacent to a lymphoedematous arm). If swelling is slow (e.g. primary lymphoedema), there may be no pain at all, except during bouts of infection. Lymphoedema is usually considered only to occur in the arm or leg, but any organ or region may suffer from it: the genitals, the gut, the lungs, the liver as a consequence of chronic hepatitis, etc. Lymphoedema has a number of other effects: it decreases mobility, causes embarrassment, can lead to depression, and causes a general worsening of the patient's life and health. If the lymphoedema is severe, especially if more than one limb is involved, the patient is excessively heavy. This may be confused with obesity, but dieting is useless if it is just lymphoedema; however if there is obesity, dieting is recommended. Even if only one limb is affected, the added weight can cause clumsiness and this makes the limb more liable to injury and consequent bacterial infection. Lymphatic drainage from the legs is more difficult than from the arms, walking is more difficult and the excess weight discourages this. So lymphoedema of the legs is often worse than that of the arms. When lymphoedema first occurs it will pit if pressed with a thumb. It gradually becomes larger and harder; it no longer pits. If lymphoedema lasts for some years, the swelling gets worse, and skin changes occur. There is loss of hair and alterations to the nails. The skin may get very thick, with huge folds and warts - elephantiasis. A few patients with long-term lymphoedema develop an angiosarcoma (Stewart-Treves Syndrome). Any lymphoedema left untreated will gradually progress along this route. What does Lymphoedema feel like? Feeling of tightness and heaviness in the limb. 'Bursting' pains Aching buttocks (leg lymphoedema) or back of the shoulder (arm lymphoedema). Pins and needles in the limb. 'Shooting' pains up the limb. A feeling of 'tightness' and tenderness in the elbow or back of the knee. Pain in joints (e.g. elbow, knee and ankle), similar to arthritis and often diagnosed as this. Tenderness in the groin of an affected leg. 'Blown up' abdomen if a leg is affected or in 'lymphoedema-all-over'. The limb or affected areas are warmer than other parts - but not red, which suggests infection (SAI) as well. In some primary lymphoedemas there can be a very gradual increase in size, but no particular pain - just a feeling of heaviness in the limb. However any infection makes it painful because of the rapid increase in size and the worsening of the lymphoedema that this causes. Joints, in particular the knee, can also become lymphoedematous - it feels like (and is often diagnosed as) 'arthritis' - which in a way it is. Sometimes lymph can leak through the skin which is then particularly vulnerable to infection. Causes of Lymphoedema There are many reasons why the lymphatic system may fail, with two main groups: primary and secondary. Primary (lack of lymphatic vessels) Usually there are simply too few lymphatics; sometimes there are many, but they are very dilated and do not pump properly; sometimes it is a combination of both. This lymphoedema can appear before birth (connatal lymphoedema), during puberty, which is most common for primary lymphoedemas (lymphoedema praecox), or later in life, e.g. from 30-40 onwards (lymphoedema tarda). Occasionally there is a narrowing of one of the major lymph trunks, e.g. at the outlet of the thoracic duct. Primary lymphoedema can also start following the onset of a secondary lymphoedema in another part of the body, e.g. postmastectomy (secondary) lymphoedema may initiate a primary lymphoedema in the leg on the same side, Secondary (blocked or cut lymphatic vessels) Secondary lymphoedema can occur if the lymphatic drainage is blocked or cut, from: 1.Surgery, especially for carcinoma with the removal of lymph nodes or a lot of tissue (e.g. an operation for melanoma) means cutting many lymphatics. 2.Radiotherapy, which kills any tumour cells, destroys the lymph nodes, blocking them with fibrous tissue. 3.Accidental trauma may tear lymphatic vessels which may not rejoin when the blood vessels do; any excess fibrous tissue caused by the damage can later shrink and constrict them. 4.Parasites (e.g. filarial worms) block the lymphatic drainage. The swelling may occur when the worms grow, damage the lymphatics and destroy their valves. It usually occurs only some years after the worms are injected - when they die and breakdown, causing inflammation which blocks the lymphatics. 5.Paralysis of a limb prevents lymphatic pumping, so causing wheel-chair oedema. 6.Chronic venous insufficiency often involves the lymphatics running beside the veins, thus eventually adding lymphoedema to the venous oedema. 7.Lipodema (this is not itself lymphoedema, but can cause it secondarily) When does lymphoedema occur, and how rapidly? Once lymphatics are damaged, lymphoedema may occur at any time. Sometimes it starts at once and lasts for life; oedema may occur for a few weeks, then go away, and may or may not return; sometimes it appears years after the event. Once the lymphatics are damaged, a very trivial thing may set it off, e.g.: a bee-sting, sunburn, carrying heavy weights, or a long aircraft flight. Apart from the acute stage which occurs briefly after the blockage and then goes away, once lymphoedema starts it gets progressively worse. This worsening is usually slow in primary lymphoedemas and rapid in secondary ones. It is usually a steady increase unless some inflammation occurs (e.g. infection, injury, burn), when it gets worse very quickly. Grades of Lymphoedema Grade 1 swelling will pit if the skin is pressed and is reduced if the limb is elevated. Grade 2 has much more excess fibrous tissue, so it does not pit, and is not much reduced by elevation (e.g. in bed overnight or for 2-3 days). The limb gradually 'hardens' because of the excess fibrous (scar) tissue due to the chronic inflammation. Elephantiasis (Grade 3) has gross changes to the skin: many protrusions & huge bulges. Regions affected by lymphoedema Primary Lymphoedema This can range from only part of one limb, to many parts of the body, including the gut (causing protein-losing enteropathy, intestinal lymphangiectasia) and lungs.