The lymphatic system develops from four cystic spaces that appear on either side of the neck and in both groins. These large cisterns develop communications (lymphatic vessels or lymphangioles) which allow most of the lymph from the lower limbs and abdomen to be channelled through the cisterna chylae into the thoracic duct, which passes up on the left side of the bodies of the thoracic vertebrae before entering the internal jugular vein in the left hand side of the neck. A separate lymphatic trunk which drains lymph from the right upper limb and right side of the head and neck enters the right internal jugular vein. Lymph nodes develop as condensations along the course of these lymphatic pathways.

Abnormalities of development result in lymphatic aplasia, cystic hygroma, lymphatic and nodal hypo- and hyperplasia, and lymphangiomas.

The lymphatic system has two main functions. The first is to remove macromolecules and excessive fluid from the interstitial space. Large molecules that escape into the tissue fluid have considerable difficulty in re-entering the vascular compartment. Proteins such as albumin, globulins, and fibrinogen that enter the interstitial fluid are usually returned to the plasma through the lymphatics. A number of coagulation factors and fibrinolytic activators also enter the lymph. Between 2 and 4 litres of interstitial fluid are returned to the vascular compartment each day by the lymphatics (Fig. 1) 642.

The second major function of the lymphatics is to allow the circulation of lymphocytes from the lymph nodes into the bloodstream. Most exogenous antigens are presented to the central lymphoid system for the first time via the lymphatics. Recognition of antigens, with subsequent proliferation of specific clones of lymphocytes, takes place in the lymph nodes. Activated lymphocytes then pass into the circulation and thus to the other lymphatic tissues throughout the body.

The interstitial space has a negative pressure and this, in combination with the hydrostatic pressures of the capillaries, encourages fluid to escape from the vascular compartment, overcoming the oncotic pressure of the plasma proteins which acts to suck fluid back into the circulation. The intraluminal pressure of the lymph system is similar to that of the interstitial fluid, and lymph capillaries must therefore actively absorb proteins through their pores. The mechanism by which this is achieved is unknown, but appears to require energy.

The lymphatic capillaries have large pores to allow large molecules to enter the lumen, and many valves that prevent the reflux of lymph and encourage its onward passage. Lymphatics have some circular smooth muscle in their wall and are capable of contraction. The combination of inherent contractility and valves ensure that lymph is propelled along the lymphatics and into the veins. Other factors that may influence lymphatic drainage include compression from surrounding arteries, and the negative pressure of the thoracic cavity sucking lymph upwards into the thorax from the abdomen.

This is defined as the excessive accumulation of interstitial fluid as a result of defective lymphatic drainage. The condition may be further subdivided into primary and secondary lymphoedema, secondary lymphoedema being the most common. Primary lymphoedema is three times more common in women than in men and has no known cause; secondary lymphoedema is the result of some recognized pathological process disrupting the lymphatic drainage.

Further subdivisions of primary lymphoedema have been made on the basis of the anatomical lymphatic abnormalities that are present. The lymphatic channels may be absent or severely hypoplastic (Fig. 2) 643, being few in number and petering out more proximally. They may also be excessive in number (Fig. 3) 644, though defective in function: such lymphatic hyperplasia is usually associated with excessive numbers of lymph nodes. The lymphatics may be dilated and ectatic (megalymphatics) (Fig. 4) 645 and this abnormality is often associated with chylous ascites, chylothorax, and lymphatic reflux. Finally the lymphatics may be obstructed (Fig. 5) 646; in primary lymphoedema this is often associated with fibrosis within the lymph nodes.

All patients presenting with lymphoedema must have a possible ‘cause’, excluded by careful examination and special tests where necessary.

This helminthic infection is a major global cause of lymphoedema. It is endemic in parts of Africa, especially the west coast, and is also common in India and parts of South America. The worm enters the lymphatics and lodges in the lymph nodes, where a severe fibrotic reaction causes obstruction to the lymphatic pathways, which are often grossly dilated (Fig. 6) 647. This results in severe swelling of the limbs (usually the lower) called ‘elephantiasis’.

The diagnosis is confirmed by finding microfilariae, which enter the blood in large numbers at night. To provide the maximum possibility of detecting filariae, a blood sample should be taken at midnight. A strongly positive complement fixation test suggests active or past filariasis.

Treatment with diethylcarbamazine destroys the filariae but does not reverse established lymphoedema; progression of the disease may, however, be slowed or prevented. Established lymphoedema is treated by the same methods as those used to treat primary lymphoedema.

Any malignant process that spreads to the lymph nodes can cause secondary lymphoedema, but this is more common after surgical resection or radiotherapy directed against nodal deposits of tumour. Hodgkin's disease and the non-Hodgkin's lymphomas can present with lymphoedema; this may also occur in patients with malignant melanomas and testicular seminomas (Fig. 7) 648.

This operation is invariably carried out to treat malignancies affecting lymph nodes, although in many cases it forms part of a staging or prophylactic procedure. The carcinomas commonly requiring block dissections are those of the breast and uterus. Malignant melanoma and testicular tumours are also often treated by block dissection or irradiation ( Fig. 8a 649, b).

Radiotherapy is a common cause of secondary lymphoedema of the upper limb in patients with breast carcinoma, especially when surgical block dissection has also been performed. Such combination therapy carries a higher risk of lymphoedema than either treatment in isolation. Radiotherapy results in nodal fibrosis, which can also cause obstruction of the lymphatic vessels. Recurrent tumour in an irradiated field may be responsible for lymphoedema developing some years after treatment of the primary disease.

Severe trauma occasionally causes loss of tissue which includes lymph nodes or lymphatic channels. This is particularly seen after severe degloving injuries.

Although tuberculosis has often been cited as a cause of lymphoedema, it is uncommon.

At the St Thomas' lymphoedema clinic one or two patients are seen every year with severe rheumatoid disease (Fig. 9) 650 or severe chronic eczema who develop mild lymphoedema. Chronic stimulation of the lymph nodes in these patients results in fibrosis and mild obstruction to the lymphatic drainage.

Severe cellulitis can occasionally damage the local subcutaneous lymphatics and cause mild lymphoedema. Patients suffering from subclinical primary lymphoedema may also develop a secondary cellulitis: the two presentations can be difficult to distinguish.

This quite common form of Munchausen's syndrome is produced by repeated tight application of a tourniquet. Total disuse of a limb can also cause swelling: this form of self-induced lymphoedema should be suspected if the limb cannot be moved passively (Fig. 10) 651. Lymphograms are usually normal or only mildly unusual. The cause should be suspected if there is a sharp cut-off to the lymphoedema and a rut due to application of the tourniquet. Patients should be told of the doctor's suspicions and referred for psychiatric advice.

Although by definition the cause of primary lymphoedema is obscure, some factors clearly influence its development. The small number of babies who have lymphoedematous limbs at birth usually have ‘aplastic’ and truly absent lymphatics. This condition (Milroy's disease) has a clear genetic predisposition in some families. How, and why the lymphatic system is damaged or malformed, is not known, but other congenital abnormalities such as yellow nails, distercerciasis, and Pierre-Robin syndrome may coexist. Some degree of inheritance can be demonstrated in about one-third of all patients with primary lymphoedema. Congenital abnormality or absence of the lymphatics does not explain why lymphoedema develops relatively late in most patients, the most common age of onset being between 10 and 25 years of age.

It is possible that the constituents of the lymph draining through the lymphatics may damage the lymphangioles or lymph nodes. Lymph may contain large amounts of fibrinogen under certain circumstances, and this may coagulate and block the lymphatics; abnormal lymph may also cause nodal fibrosis which may lead to ‘die-back’, or disappearance of the lymphangioles. The primary disease may therefore be in the node, and this may cause the lymphatic hypoplasia. Anticoagulant therapy has been reported to produce improvement in patients with lymphoedema, lending some support to the concept that hypercoagulability of lymph may be harmful. Molecules as yet unrecognized within lymph may also be harmful to nodes and lymphatic vessels. None of these explanations accounts for the development of hyperplastic or dilated lymphatics.

Primary lymphoedema is much more common in the lower limbs than in the upper limbs: although this is partly explained by the influence of gravity, anatomical abnormalities are rarely present in the lymphatics of the upper limb.

The swelling may affect one or both lower limbs, the lower abdomen, the genital region, one or both upper limbs, and, rarely, the face or chest. In the lower limbs swelling usually develops around the ankle and on the dorsum of the foot, and spreads proximally (Fig. 11) 652. In the majority of patients the oedema does not spread above the knee, but severe oedema of the whole limb including the buttock (Fig. 12) 653 suggests a proximal nodal lymphatic occlusion. There are exceptions to this rule, however, and patients with proximal lymphatic occlusions may have no oedema of the ankle or foot. Because lymphatic oedema is chronic and has often been present for many years it stimulates a fibrotic reaction in the subcutaneous tissues, making them more resistant to deformation than is the case in acute oedema associated with cardiac failure or hypoproteinaemia. However, prolonged digital pressure will always produce a ‘pit’. If such pitting cannot be demonstrated the diagnosis of lymphoedema must be questioned and another cause for the swelling should be sought.

The onset of the swelling is usually insidious, and it may fluctuate. Even when lymphoedema becomes fixed all patients report that the swelling decreases during sleep and is maximal at the end of the day. Onset can occasionally be sudden, and progression rapid. This is often associated with cellulitis, which can be both a cause and a result of lymphoedema. Patients with sudden severe swelling usually have a proximal lymphatic occlusion and may have an underlying cause for the condition. Patients with malignant obstruction of both the veins and lymphatics often develop a severe brawny oedema of rapid onset that can cause intractable pain which may be very difficult to alleviate. Some patients develop marked cutaneous thickening which can progress to lymphatic warts (condylomata) and multiple coarse papillae. Other patients are troubled by repeated attacks of cellulitis. The infecting agent may enter through the hyperkeratotic skin or through cracks in the interdigital clefts which occur in athletes' foot.

Occasionally patients develop numerous vesicles in the skin which may leak clear lymph or, occasionally, chyle. These vesicles usually indicate that there are megalymphatics (Fig. 13) 654 and lymphatic reflux. Vesicles usually arise over the upper thighs or on the external genitalia, and they may also act as a portal of entry for bacteria. Occasionally the lymph leakage from these vesicles is severe enough to be a major source of embarrassment and irritation.

Severe oedema of the male genitals is both embarrassing and uncomfortable, interfering with work and sexual relationships. Penetration may be impossible and urination may be difficult when the penis is almost hidden inside a grossly swollen scrotum. Leaking vesicles and recurrent attacks of cellulitis often complicate the condition. Women with genital oedema usually have fewer problems but massive labial swelling can be uncomfortable and embarrassing (Fig. 14) 655.

Lymph can leak into both the abdominal and pleural cavities, causing chylous ascites and pleural effusions. Patients present with abdominal distension, dyspnoea, or both. These problems are usually the result of leakage from refluxing megalymphatics; chyluria and chylous leakage from the vagina are rare complications. Protein-losing enteropathy can cause severe weight loss (Fig. 15) 656 and chylous leakage from the serosal surface of the bowel may increase the ascites.

Lymphoedema may occasionally affect the upper limb, including the fingers (Fig. 16) 657 and unilateral pectoral swelling can also occur. Oedema of the face usually presents as swelling of the eyelids, which are the most lax tissues in this region.

Patients with lymphoedema usually seek advice because they want to know the cause of the swelling, which causes major cosmetic embarrassment, even though it is often only of nuisance value. Severe swelling may make it impossible to buy shoes, and if the limb continues to swell its weight interferes with normal walking. Recurrent attacks of cellulitis may also be a major problem. Lymphangiosarcoma (Stuart Treves syndrome; Fig. 17 658) can infrequently develop in limbs following long-standing lymphoedema, but is more often a problem in patients with secondary lymphoedema.

A detailed past and family history should exclude secondary causes of lymphoedema and should suggest a possible inheritance of the primary condition. Apart from confirming the presence of pitting, physical examination excludes other causes of limb swelling and reveal any associated abnormalities. ‘Square toes’ often result when footwear prevents toe expansion. It is important to inspect the web spaces between the toes for athletes' foot, which is especially common in lymphoedematous limbs and is an important portal of entry for bacteria that cause recurrent cellulitis. Yellow nail syndrome is occasionally associated with lymphoedema, as is distichiasis (two layers of eyelashes). Occasionally Pierre-Robin syndrome (micrognathia) and other skeletal abnormalities are present, and congenital cardiac anomalies are found also in patients with lymphatic hyperplasia.

The skin should be carefully examined for papillae and vesicles, and the limbs should be measured at fixed levels, above and below fixed bony points (Fig. 18) 659, to allow both the natural history and the results of therapy to be evaluated. The length of the limbs should also be measured and the presence of any abnormal veins must be recorded. The abdomen and chest should be carefully examined for ascites or effusions. The groins and axillae should be palpated for pathologically enlarged lymph nodes. Rectal and vaginal examinations are indicated if a pelvic malignancy is suspected.

The physical examination should provide indications of whether the patient has primary or secondary lymphoedema, but unequivocal confirmation of the diagnosis is desirable. If the swelling is not the result of lymphoedema, other investigations are necessary.

Venous oedema can sometimes be difficult to differentiate from lymphoedema, especially if it is caused by the iliac vein compression syndrome, when there is often little in the way of superficial venous engorgement. The presence of dilated collateral veins or varicose veins normally suggests venous oedema, as does a past history of deep vein thrombosis. Other causes of bilateral limb oedema include cardiac disease, nephrotic syndrome, hypoproteinaemia, fluid overload during intravenous therapy, and chronic liver disease. These disorders can be excluded by a careful physical examination and appropriate blood tests. Klippel Trenauney and Parks-Weber syndromes also cause limb enlargement: the former is occasionally associated with lymphoedema. True gigantism (Robertson's giant limb) also occurs, when all the tissues (muscles and bones) are hypertrophied. Abnormal fat deposition (lipoidosis or lipodystrophy) can be excluded by the fact that fat does not pit (Fig. 19) 660. Periodic oedema experienced by women before menstruation is often difficult to separate from lymphoedema. Rapidly growing soft tissue sarcomata rarely cause diagnostic problems. Before making a diagnosis of one of these rare conditions, for which venography, CT scanning, and arteriography may be required, it is often simpler to exclude lymphoedema by isotope lymphography.

A full blood count, erythrocyte sedimentation rate, and chest radiographs are usually requested, but these investigations can be omitted. Measurement of serum protein, blood urea, creatinine, and electrolyte levels and liver function tests should be obtained in all patients.

This is indicated to confirm the diagnosis and to determine, if possible, the type of lymphatic abnormality that is present. This investigation originally required direct infusion of contrast into lymphatics that were visualized by subcutaneous injection of patent blue green into the web spaces (Fig. 20) 661: patients had to be admitted to hospital for the investigation, and general anaesthesia was usually necessary as few patients could keep still for the time required to obtain the radiographs. Such patients often require bed rest and leg elevation in hospital for several days to minimize foot oedema and make lymphatic cannulation easier. Lymphangiography does, however, provide precise information on the presence of hypoplasia, megalymphatics, and obstruction (including its site), and it still remains the ‘gold standard’ against which other techniques are judged. It is still essential before certain therapeutic options are considered, and is of some value in assessing prognosis.

Isotope lymphography has largely replaced contrast lymphangiography as the primary diagnostic technique. Rhenium sulphur colloid is specifically taken up by lymphatics and allows the presence of lymphoedema to be confirmed by a simple outpatient investigation. Normally, 0.3 per cent of the injected dose arrives in the groin within 30 min, and more than 0.6 per cent arrives within 1 h. In patients with venous oedema there is an excessive uptake, often above 3 per cent at 30 min, and this test can therefore distinguish between venous and lymphatic oedemas. Gamma-camera pictures provide information that the isotope is reaching the lymph node of the groin and delayed images may show a failure of progression, indicating proximal obstruction (Fig. 21) 662. This should be confirmed by contrast lymphography, as should any equivocal findings. An attempt has been made to produce a special contrast media which was selectively taken up by the lymphatics from a subcutaneous injection. The prototype contrast material has not yet found its way into routine clinical practice.

Ultrasound imaging, CT scanning, and magnetic resonance scanning can all show enlarged lymph nodes, and guided biopsies of lymph nodes can be taken if malignancy is suspected. Needle or true-cut biopsies are probably safer as a preliminary procedure, since removal of large solitary fibrotic nodes may worsen pre-existing lymphoedema. A calcium chloride test may be helpful when protein-losing enteropathy is suspected.

Many surgeons are content to diagnose mild lymphoedema from the history and physical findings without investigating the patient further. This clinical diagnosis can however be incorrect and isotope lymphography should be obtained if possible. This not only provides a firm diagnosis, but also allows an assessment to be made of prognosis and of possible problems that may be present in the contralateral limb. Young women with mild lymphoedema of gradual onset usually have distal lymphatic hypoplasia: there is prolongation of the time taken for the isotope to reach the groin nodes, but normal onward passage. This type of lymphoedema is often inherited (at least 30 per cent), and rarely becomes severe or extends above the knee. It is often bilateral but one limb may be affected several years before the other. Rarely, the upper limbs are also involved.

Patients with this condition rarely require surgery. They should be given advice on limb elevation, especially in the evenings and at night, and some patients benefit from regular massage or mechanical compression combined with wearing of graduated elastic compression stockings. Pneumatic massaging devices are obtainable, and sequential segmental machines such as the lymphopress (Fig. 22) 663 are probably more effective than single chamber boots. These may be worn in the evenings or in bed at night, although they may interfere with sleep. Correctly graduated strong compression stockings (30–50 mmHg at the ankle, decreasing up the limb) only need to reach below knee level if the lymphoedema is distal in distribution. Elastic compression stockings do not cure lymphoedema, but they reduce fluid accumulation and often produce considerable symptomatic relief. They are poorly tolerated in warm climates and young women tend to be conscious of their appearance. Weight reduction is often beneficial and physical exercise is never harmful; concentrated compression therapy and massage may also reduce the size of lymphoedematous limbs.

Diuretics are of little value in removing fluid from the whole body and may cause a number of problems when used unnecessarily for many years. Paroven (hydroxyrutosides) has some anecdotal support, as do the coumadins, but these compounds have not yet been tested in a well controlled clinical trial.

Antibiotics (flucloxacillin, amoxycillin, or one of the cephalosporins) should be prescribed for cellulitis and may be given in a low dose prophylactically if patients are troubled by repeated attacks. Athletes' foot must be eradicated by appropriate antifungal medication and creams. Careful attention to drying and powdering of the feet prevents infection and avoids an important portal of entry for virulent bacteria.

Surgical reduction of severe whole limb lymphoedema that interferes with mobility or causes severe deformity (Fig. 23) 664 is often appropriate. In a small proportion of patients preoperative contrast lymphangiography discloses a proximal lymphatic obstruction in the ileoinguinal region with normal distal limb lymphatics (Fig. 24) 665. These patients (1–3 per cent of all those seen) can be expected to benefit from some form of lymphatic bypass operation.

A number of methods have been used to reunite obstructed lymphatics with the venous system. Many of these techniques, such as the skin bridge devised by Gillies and the omental pedicle, both of which were sutured to the obstructed lymph nodes in the groin, are only of historical interest. Direct anastomosis of lymph nodes to veins was originally performed by Niebulowitz, but fibrosis and low flow rates resulted in a high failure rate. Degni used a specially designed needle to insert lymphatics into the lumen of the vein, but the imprecise nature of this procedure has prevented its widespread acceptance. The advent of the operating microscope has made it possible to divide obstructed lymphatics and directly anastomose them into the side of the vein. However, the results have generally been disappointing. At least three of four lymphatics should be attached to the femoral vein in the groin in the hope that one or two anastomoses will remain patent.

Kinmonth and his associates developed the mesenteric bridge as an alternative to direct lymphovenous anastomosis. This operation uses the copious submucosal lymphatic plexus and the mesenteric lymphatics to drain the lymph from obstructed nodes in the ileoinguinal region. About 5 cm of the terminal ileum is resected on its mesenteric pedicle, as for an ileal conduit, taking great care to maintain the lymphatic drainage. The small bowel is reanastomosed behind the pedicle. The isolated segment is then opened along its antimesenteric border and the mucosa is stripped off the submucosa by a combination of sharp and blunt dissection after injection of a solution of adrenaline in saline (1:400 000). The isolated pedicle is then brought down to the first normal group of lymph nodes below the level of the obstruction, and sutured over them after they have been bivalved. Connections develop between the divided nodes and the submucosal plexus and lymph drains up the pedicle into the mesenteric lymph nodes, and eventually into the thoracic duct (Fig. 25) 666.

This operation has been performed on over 40 patients at St Thomas' Hospital, London and has produced good results in more than half. Unfortunately there is no way of predicting those who will benefit from the procedure, although the careful selection of patients prevents inevitable failure. Young patients appear to fare better, and the distal limb lymphatics must still be functioning if a successful result is to be achieved. If limbs are too swollen resolution is poor, but swelling must be severe enough to justify major abdominal surgery. Perhaps for this reason surgery is appropriate for relatively few patients.

Four types of excisional operation have been described to reduce the size of the limb. The Sistrunk operation involves excision of a large wedge or ellipse of skin and subcutaneous tissue which is then closed primarily. Homan elevated skin flaps from the subcutaneous fat, excising the underlying subcutaneous tissue before resuturing the skin flaps in place (Fig. 26) 667. Thompson modified the Homan's operation by suturing one of the skin flaps to the deep fascia. Denudation of the superficial layers of the flap stops hair growth and prevents pilonidal sinus formation. The second flap is then sewn over the top of the denuded skin area (Fig. 27) 668. This operation has largely been abandoned: it leaves unsightly scars, it is often complicated by pilonidal sinus formation, and the results appear to be no better than those of the simpler Homan's procedure.

Both Homan's and Thompson's operations can be complicated by skin flap necrosis and poor healing, particularly at the corners of the flaps. Great care needs to be taken to maintain the blood supply of the flaps, which must not be cut too thin. Flap reduction of the calf and foot is normally combined with a Sistrunk operation on the thigh if the whole limb is to be reduced in size (Fig. 26) 667.

Charles invented an operation to remove the severely thickened skin in patients with filariasis. He excised all the diseased skin and the waterlogged subcutaneous tissue down to, and often including, the deep fascia from just above the ankle to just below the knee. The periosteum over the tibia was left intact and split skin grafts were then taken from normal donor skin (the opposite normal limb, or the abdomen, back, and buttocks) and used to cover the deep fascia or muscle. This operation produces the best reduction in limb size, but often at the expense of cosmesis. The ankle and knee area have to be carefully tailored to avoid a pantaloon effect (Fig. 28) 669, and thigh reduction is also often necessary. Some patients have a poor acceptance of split skin grafts and require multiple operations to achieve complete healing. Other patients develop severe hyperkeratotic scars with warty excrescences, which produce severe deformity in the operated limb (Fig. 29) 670. This can be treated by shaving off the warty nodules and thickened scars with a scalpel or skin graft knife; additional skin grafts are occasionally needed. However, final results are usually very satisfactory, especially in a grossly enlarged limb with very abnormal calf skin.

The majority of patients can be managed conservatively. Few patients are suitable for bypass surgery: when surgery is indicatd an enteromesenteric bridge is probably the best form of bypass, having a spectacular effect in about half of the patients. Bypass surgery should be reserved for patients with gross limb swelling that interferes with limb function. Patients with really gross limb swelling and severe skin changes are best treated by a Charles reduction, combined with a local excision of enlarged thigh tissue. Homan's operation should be reserved for those with a moderate to severe degree of swelling. Patients with secondary lymphoedema caused by malignancy often have associated venous oedema. The results of reduction surgery under these circumstances are extremely poor.

Minor scrotal and penile lymphoedema can be tolerated without specific treatment, although support garments may be helpful. Severe scrotal oedema is best treated by excisional reduction surgery in which a large central segment is excised from the scrotum, preserving the spermatic cords and testicles. The flaps are then primarily sutured using an absorbable material and the scrotum is drained. Mobilization of the testes with gentle abrasion of their surfaces may encourage adhesions to form, allowing lymph to drain via the testicular lymphatics, aiding the scrotal reduction.

The penis may be reduced by simple excisional procedures, combined with circumcision if necessary. Alternatively the skin and subcutaneous tissue can be stripped off the deep fascia and split skin grafts applied (a Charles operation of the penis). Both scrotal and penile reduction operations produce gratifying results for surgeon and patient.

Eyelid swelling can be treated by lid reduction. Arm swelling can be treated by a Homan's type of limb reduction, which can be performed on both the inner and outer sides of the upper limb. Patients with postmastectomy oedema must be assessed carefully to ensure that the venous drainage is satisfactory and to be certain that there is no evidence of recurrent axillary nodal disease. Both venous obstruction and recurrent malginancy are contraindications to arm reduction. Postoperatively an elasticated sleeve should be worn to try to prevent recurrent swelling.

Liposuction has been used to remove subcutaneous fat in patients with mild lymphoedema. Anecdotal successes have been achieved but the cosmetic results are variable and the procedure should be used with caution.

Some patients have dilated (almost varicose) valveless megalymphatics which allow the reflux of lymph (often chyle) against the expected direction of flow. These dilated lymphatics often end in cutaneous vesicles which are visible in the skin or which may rupture into body cavities such as the pleura (see Section 35.9) 67, peritoneum, kidney (see Section 41.16) 68, bladder, uterus, and vagina. Rupture results in the accumulation of lymph or chyle in the relevant cavity (chylothorax, hydrothorax, chylous ascites, chyluria) and chylous discharge on to the skin surface or mucosa can also occur. Accumulation of chyle in the pleural and peritoneal cavities produces severe symptoms, and patients often become dyspnoeic and very distended. Patients with megalymphatics often also have a protein-losing enteropathy which can cause weight loss and exacerbate accumulation of fluid in the body cavities and tissues. This results from leakage of lymph from the mucosal surface of the bowel; associated lymphatic leakage from the serosal surface may exacerbate the accumulation of ascites.

The diagnosis of chylous ascites or chylothorax must first be confirmed by aspiration of the fluid, which is then tested for chylomicrons. The condition may be suspected if there is pre-existing lymphoedema of the extremities and it is especially likely if vesicles and lymphatic leakage are present. However, in quite a few patients the condition develops de novo. Chylothorax and chylous ascites must be distinguished from malignant ascites or a malignant effusion: cytological examination of the aspirate may help to exclude or confirm the presence of malignant cells. CT scan and ultrasound can demonstrate the presence of moderate or severe enlargement of the abdominal or mediastinal lymph nodes which suggests the possibility of a lymphoma or secondary malignant spread. Guided biopsy, laparoscopy, or laparotomy may be necessary to confirm these diagnoses. Contrast lymphography demonstrates lymphadenopathy, filling defects, or the presence of megalymphatics and is indicated if the diagnosis remains in doubt. Contrast lymphography may also demonstrate a lymphatic leak which can be surgically sealed.

Lymphoedema associated with megalymphatics rarely requires reduction surgery, but the complications of lymphatic vesicles, recurrent infections, lymphatic discharge on to the skin, chylous ascites, chyluria, and chylothorax often demand treatment. Leakage of chyle or lymph may be prevented by ligating or under-running the dilated lymphatic channels, but this carries the risk of lymphatic obstruction which will worsen the limb swelling. Despite this many patients benefit from ligation of dilated lymphatics, and sealing off of any obvious site of fistulation.

If a patient with chylous ascites or chylothorax has no obvious leak on the lymphangiogram, chromium chloride studies and a barium study of the small bowel may provide useful information before a laparotomy is performed. At laparotomy the posterior abdominal wall over the main lymphatic pathways must be carefully inspected for the presence of lymphatic leakage, and the whole of the intestine should be examined. If the surface of the small bowel is grossly abnormal and leaking lymph, the involved or most abnormal segment should be resected. If this simple approach fails, consideration must be given to shunting the ascites back into the venous system using a LeVeen or Denver shunt. Although these shunts often work well in patients with refractory ascites, chyle often blocks the plastic tubing, or the valve, and produces an early occlusion of the shunt. Many patients improve with simple avoidance of fat and prescription of medium chain triglycerides combined with diuretics.

Chylothorax may respond to aspiration but often recurs and is best prevented by some form of pleurodesis induced with talc, tetracycline, bleomycin, or pleural stripping. After these procedures some patients die from water- or lymph-logged lungs as the lymphatics draining the lung become obstructed when they are no longer able to empty into the pleural cavity. Nevertheless many patients with severe problems as the result of megalymphatics can be helped by some of the procedures outlined above. Cutaneous vesicles may be simply excised or touched with the diathermy or cautery, but they tend to recur. Recurrent infections should be treated by a prolonged course of broad-spectrum antibiotics.

These lesions are either considered as hamartomas or as localized abnormalities of the cutaneous lymphatic drainage. They present as a number of clear or slightly haemorrhagic cutaneous vesicles, often associated with subcutaneous thickening in the underlying fat (Fig. 30) 671. Whimster thought that a lymphangioma circumscriptum was the result of defective lymphatic drainage from the subcutaneous tissue where a number of cisterns ‘pump’ lymph back into the overlying skin. These areas should be excised if they are unsightly or painful. They often occur on the trunk and it is important to excise a generous amount of subcutaneous tissue well beyond the ellipse of skin bearing the vesicles in order to remove the subcutaneous bladders described by Whimster. It is often quite difficult to excise all the skin lesions and they have a propensity to recur: excisional surgery is only required if they are symptomatic.

In this developmental abnormality of the lymphatic system, lymphatic fluid collects in a cystic space which is often multilocular and situated in the base of the neck. Cystic hygroma commonly appears in childhood and presents as a soft, brilliantly translucent swelling in the base of the neck. Aspiration and injection of sclerosant may be attempted, but the swellings often recur and may require excision. Cystic hygromas must be dissected with great care as a number of important structures lie adjacent to them.

These localized lymphatic cysts within the mesentery appear as well-circumscribed mobile lumps within the abdomen. The diagnosis can be confirmed by ultrasound or CT scanning. They are treated by resection, often in association with the overlying area of small bowel. Although harmless, they may reach a considerable size if left untreated.

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