Practical Ambulant Lymphology.
Lymphology represents the study of the lymphatic system, a system described one year before William Harvey's De Mote Cordis described the circulation. The relative importance of lymphatic diseases to cardiovascular diseases in modern medicine does not bear comparison. This is essentially because there are few fatal lymphatic diseases, but another reasons that the full function of the lymphatic system and its contribution to disease, remains largely unknown even today. Difficulties of investigation have largely contributed, but so has a lack of interest. Any text which generates interest and raises awareness of lymphology is therefore to be welcomed.
1. Anatomy of the lymphatic system of the extremities
1.1. Lymphatic tree
1.1.1. Lymphatic capillariesThe superficial capillary network of the lymphatic system of the extremities lie in the skin and flow into the dermal capillary plexus deep in the corium.
The lumen of lymphatic capillaries is between 0.1 um and 100 um in diameter and highly elastic compared with the capillaries of blood vessels.
1.1.2. Pre-collectorsThe pre-collectors have a diameter of 130 um to 150 um and are located in the deep corium and subcutaneous tissue. They collect the lymph drained by the capillary network and convey it to the collecting vessels.
1.1.3. Lymphatic collectorsIn the lymphatic collecting vessels which are between 150 um and 160 um in diameter, lymph is collected and conveyed through a direct opening into the major lymphatic trunks.
1.1.4. Lymphatic trunksThe largest lymphatic trunk, the thoracic duct, carries lymph from the lower half of the body and the posterior mediastinum.
The ducts on the right of the body join to form the right lymphatic duct. The opening of the lymphatic ducts into the veins is subject to considerable anatomical variation; it is located in the supra-clavicular fossa, in the angle formed by the internal jugular and subclavian veins.
1.2. Lymph nodesThe lymph nodes, through which the lymph flows, are lymphatic organs with a number of functions associated with their specific tissue structure.
a.) Lymph supplied by the afferent lymph vessels is biologically filtered in the lymph nodes.
b.) Lymphocytes are produced in the lymph nodes.
c.) Lymph nodes regulate the protein content of lymph, which is then carried away by the efferent lymph vessels.
The lymph vessels are embedded in fatty tissue and accompany the chains of lymph nodes along the blood vessels.
1.3. Lymphatic territoriesSmall areas of the skin are joined together by capillaries and pre-collectors which drain these areas via subcutaneous collectors.
A lymph territory is that area of skin drained by the collectors of a single lymphatic plexus.
Between these territories are interterritorial zones with few vessels; these may be described as the lymphatic watershed areas.
The passage of lymph from one lymphatic plexus to the next is possible only via the initial vascular network of the watershed area.
2. Micromorphological characteristics of the lymphatic vessels
2.1. Lymphatic capillaries - Pre-collectorsLymphatic capillaries or initial lymphatic vessels are structures starting as blind tubes of endothelium under the skin. These are covered with a basal lamina which is discontinuous.
The elasticity of the endothelial cells is very high, since they can overlap, interdigitate and fold. There is no tight junction connection with the adjacent endothelial cells. These cells are in direct contact with the microfilaments of the surrounding connective tissue which are anchored as collagen and elastic fibres in the capillary wall. The cells can open and close the capillary wall in response to changes in pressure.
The capillaries have no pericytes and exhibit a valve structure with the same function an the pocket valves in veins.
2.2. Collecting vesselsThe superficial subcutaneous collecting vessels follow the major veins of the skin and open into the deep main collectors, the drainage area of which corresponds to that of the main veins.
The walls of the collecting vessels is surrounded by basal lamina, microfilaments and smooth muscle cells. The wall contains networks of nerve fibres; valves made of reticular fibres coated with endothelium project into the lumen.
3. Physiology of lymph productionThe lymphatic capillaries do not consist of continuous vascular tubes but of groups of segments. Each functional unit is autonomous and is known as a lymphangion. The centripetal flow is maintained by valves which isolate the individual segments from each other.
The flow of lymph is determined by the relationship between interstitial and intraluminal pressure. During the filling phase, the pressure in the interstitial space is higher than the intraluminal pressure in the lymphangion, and fluid and other substances can flow into the lumen.
The centripetal flow of lymph entering the lymphangion is determined by four factors:
1. The hydrostatic pressure gradient
2. Colloid osmotic pressure
3. The muscle pumps
4. The independent contraction of the segment
In the emptying phase, intraluminal pressure is higher than interstitial pressure; the proximal lymph valves open as a result of segment contraction, the lymph flows towards the centre, into the central lymphangion.
The hydrostatic pressure gradient causes some of the fluid to diffuse through the endothelial wall. Since proteins and other substances of high molecular weight cannot pass the endothelial cells, they remain concentrated in the lymph.
The lymphatic capillaries act as tiny pumps with alternating pressure and suction
Diagram of the pumping function of the lymphatic capillaries
4. Definition of lymphoedema
4.1. Clinical pictureLymphoedema occurs as a result of a mechanical of dynamic failure which reduces the capacity of the lymphatic system to transport lymph, after all compensating devices have been exhausted, below that required by the lymphatic burden.
There are certain substances that need to be transported by the lymphatic vessels from the interstitial space and returned into the venous system; they have no alternative transport pathway. These substances include not only water but also fats, proteins and various types of cell residues.
The clinical manifestation of lymphoedema is swelling, caused by protein-rich fluid, cells and other substances which accumulate in the interstitial space. In oedema, fluid can be displaced like dough. Fingertip pressure on the skin produces a depression which disappears after a few seconds. This is known as pitting oedema. In the late stage of oedema, the tissue fluid can no longer be displaced, so that this is known as non-pitting oedema.
- Swelling of the affected extremity
- Fitting or, oedema late stage, non-pitting in the
- Normal or pale skin colour
- Positive Stemmer's sign (skin over toes can barely be lifted)
- Mounds of swelling on dorsum of foot or hand
- Toes swollen like sausages, square in the late stage
- Indentation and deep skin folds on ankle and Achilles tendon
- Deepening of skin folds of wrist
- Dermal papillomatosis
- Microbial eczema, mycosis, pyoderma, lymph fistulae, heratosis, angiomas, etc.
4.2. Stages of lymphoedemaStage I
Reversible pitting oedema, which develops after physical exertion or at the end of the day and disappears spontaneously after a night's rest.
Reversible pitting oedema with complications such as eczema and erysipelas, which does not disappear spontaneously but can be cured by the appropriate treatment.
Irreversible, non-pitting oedema due to fibrosclerosis with complications such as eczema, erysipelas, papillomatosis, and lymph fistulae. The existing tissue proliferation remains even after specialist treatment.
Elephantiasis, irreversible oedema with complications such as papillomatosis, keratosis, lymph fistulae and angiomas.
4.3.1. Primary lymphoedemaThe cause of the oedema is hypoplasia or hyperplasia of the lymphatics
- Congenital lymphoedema
- Lymphoedema praecox
- Lymphoedema tarda
4.3.2. Secondary lymphoedemaThe cause of the oedema is a known disease.
- Tumours - lymphoedema of malignancy
- Extirpation or irradiation of lymph nodes and lymph ducts due to malignant disease
- Trauma with tissue destruction
- Surgical procedures with inadvertent damage to lymph ducts
- Infections, bacteria, fungi
- Artificial lymphoedema
- Angiovenous insufficiency
- Chronic venous insufficiency
5. Diagnosis and differential diagnosis of lymphoedema
5.1. Case history and clinical examinationThis is extremely important and sufficient to establish a diagnosis in the majority of patients.
5.2. Diagnostic investigationsNot generally necessary
Diagnostic investigations are necessary
- to exclude malignant processes,
- to prepare for surgical treatment,
- to determine vascular status,
- for classification of manifest lymphoedema in patients of advanced age.
Differential diagnostic problems in
- post-thrombotic syndrome
- chronic venous insufficiency
5.2.1. Lymphangiography -with oily contrast media is not recommended, as the lymphoedema generally worsens after the investigation; almost no useful information is provided.
5.2.2 Indirect lymphangiography -with aqueous contrast media, to determine
- the initial pattern of the lymphatic capillaries
- the number, length and morphology of the collecting vessels.
A reduction in the collectors, short image length, no image or twisted collecting vessels indicate:
5.2.3. Magnetic resonance imaging (MRI)Non-invasive method for the differential diagnosis of unexplained oedema of the legs. Since the lymphatics are clearly visible and dilated, this method is suitable for the detection of changes in soft tissues.
5.2.4. XeroradiographyMethod of diagnostic radiological examination of the soft tissues which allows differentiation between lymphoedema and other swellings of the extremities
5.2.5. Fluorescence micro lymphographyThis is not generally necessary for routine diagnosis.
5.2.6. Lymphatic scintigraphyIsotope lymphangiography is used for functional diagnostic investigation and shows the transport pathways and deposits of isotope contrast medium.
Lymphatic scintigraphy is not suitable for use in the lymph nodes to differentiate between metastatic involvement, surgical damage or lesions due to irradiation.
6. Micromorphological pathology of lymphoedema
6.1. Pathology of the lymphaticsLymph stasis caused by protein-rich fluid between the fibres of connective tissue in the extravascular space, leads to an increase in vascular wall permeability, fibrin deposits and gradual breakdown of the connective tissue with chronic inflammation.
- There is an increase in granulofilamentous, basal laminar material around the lymphatic vessels,
- The number of small microfilaments is reduced,
- Lipid deposits are visible in the endothelial cells
- Cytoplasmic inclusions indicate that the vascular wall is subject to metabolic disorders
- The affected lymphatic vessels show valvular insufficiency,
- New lymphatic capillary buds are organised,
- Pericytes appear.
6.2. Pathology of blood vessels- The basal laminae of the blood vessels are multi-layered,
- Neutrophilic granulocytes, lymphocytes and monocytes are found in the oedematous vascular wall,
- Cytoplasmic inclusions indicate that the vascular wall is affected by metabolic disturbances,
- The capillary lumen is filled with red blood cells,
- Fibrin deposits are visible in the extra vascular space.
The pathological changes in the blood vessels can be the described as lymphostatic haemangiopathy.
6.3. Pathological changes in the connective tissue- The ground substance is increased,
- The inflammation consists of neutrophilic granulocytes, lymphocytes, plasma cells and histiocytes,
- Myofibroblasts appear,
- Macrophages are increased,
- Degenerative forms of collagen are observed,
- The elastic peri-vascular fibres are degenerated.
7. Complications of lymphoedema
7.1. Most common complicationsClinical symptoms occurring as complications of chronic lymphoedema must be regarded as serious signs.
- Lymphocutaneous fistulae
- Skin changes such as mycosis, eczema and keratosis
- Dermal papillomatosis
- Angioma, pseudo-Kaposi's syndrome
7.2. Assessment of complicationsVigorous prophylaxis is required to avoid complications, since a vicious circle will otherwise develop in which the lymphoedema continues to worsen.
- The patient's symptoms are worsened by fever and pain,
- eczema, angioma and mycosis may develop,
- lymphocutaneous fistulae, new sources of infection develop,
- the patient's ability to compensate is severely limited by papillomatosis
- life threatening angiosarcomas may develop,
- admission to hospital for treatment for erysipelas and weeping eczema increases treatment costs.
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