Secondary
Lymphoedema
Filariasis
This is the commonest cause of lymphoedema worldwide, affecting up to
100 million individuals. It is particularly prevalent in Africa, India and South
America where 5—10 per cent of the population may be affected. The viviparous
nematode Wucheria bancrofti, whose only host is humans, is responsible
for 90 per cent of cases and is spread by the mosquito. The disease is
associated with poor sanitation. The parasite enters lymphatics from the blood
and lodges in lymph nodes where it causes fibrosis and obstruction, due partly
to direct physical damage and partly to the immune response of the host.
Proximal lymphatics become grossly dilated with adult parasites. The degree of
oedema is often massive, in which case it is termed ‘elephantiasis’ (Fig.
17.10). Immature parasites (microfilariae) enter the blood at night and can be
identified on a blood smear, a centrifuged specimen of urine or in lymph itself.
A complement fixation test is also available and is positive in present or past
infection. Eosinophilia is usually present. Diethylcarbamazine destroys the
parasites but does not reverse the lymphatic changes; although there may be some
regression over time. Once the infection has been cleared treatment is as
for primary lymphoedema. Public health measures to reduce mosquito breeding, protective clothing and mosquito netting
may be usefully employed to combat the condition.
Malignancy
and its treatment
This is the most common cause of lymphoedema in developed countries.
Hodgkin’s and non-Hodgkin’s lymphoma may present with lymphoedema, as may
malignant melanoma which has metastasised to regional lymph nodes (Fig.
17.11)
and malignancy of the pelvic organs (ovary, uterus, bladder), anus, prostate,
testes, penis and breast (peau d’orange). More often lymphoedema is a
result of treatment, either surgical excision of draining lymph nodes and/or
radiotherapy. Lymphoedema following treatment for breast carcinoma is the
commonest example, but fortunately this is decreasing in incidence as surgery
for the condition has become more conservative (Fig.
17.12). Lymphoedema may
occur after radical mastectomy (up to 60 per cent), modified radical mastectomy
(up to 20 per cent), local excision with either axillary node clearance or radiotherapy
(less than 5 per cent), and local excision with axillary node clearance and
radiotherapy (up to 40 per cent).
This is an unusual cause of lymphoedema but is especially seen after
degloving injuries of the extremities.
Acute cellulitis
As described above,
acute bacterial lymphangitis is a frequently observed triggering event for
secondary lymphoedema.
Other causes
Other rare, but well-documented, causes of secondary lymphoedema
include tuberculosis, rheumatoid arthritis (chronic inflammation and lymph node
fibrosis), and snake and insect bites. It is likely that deep venous thrombosis,
chronic venous insufficiency and superficial thrombophlebitis can lead to
lymphoedema. Indeed, lymphatic abnormalities are frequently observed in
patients who have the skin changes of chronic venous insufficiency and venous
ulceration.
Factitious
Lymphoedema
This may be caused by application of a tourniquet (a rut and sharp
cut-off is seen on examination) or ‘hysterical’ misuse.
Investigation
of Iymphoedema
Are investigations necessary? Many clinicians diagnose lymphoedema
purely on the basis of history and examination, especially when the swelling is
mild and there are no apparent complicating features. Severe swelling, with
unusual features, or where there may be more than one pathology contributing to
the clinical picture usually warrants further investigation. Not only will this
allow the diagnosis to be confirmed, but it may also provide useful prognostic
information and guide management decisions.
Investigation
techniques
‘Routine’
tests. A full blood count, plasma urea and electrolytes, creatinine, liver
function tests, chest radiograph and midnight blood
Contrast
lymphangiography. Although few centres now perform this technique, it remains
the standard by which all other lymphatic imaging is judged and provides
precise information about the anatomy of the lymphatic system. It is now
generally reserved for preoperative evaluation of patients with megalymphatics
who arc being considered for bypass or fistula ligation.
Technique
(Kinmonth, Browse, Wolfe). The patient
is admitted for limb elevation to reduce swelling and facilitate lymphatic
cannulation. Originally a vital dye such as patent blue was injected and its
ascent in the lymphatics to the regional nodes (in about 5—111 minutes) simply
observed with the naked eye (visual lymphangiography). In patients with
obliterated lymphatics dermal backtlow could he observed soon after injection
and the appearance of dye at the groin was delayed. This technique was soon
replaced with direct contrast lymphangiography. Under local anaesthesia, a small
transverse incision is made in the dorsum of the foot after I ml of isosulphan
blue has been injected subcutaneously to identify the lymphatics. Lymphatics are
dissected out under loupe magnification and a 30G needle used to infuse
lipid-soluble contrast at a rate of I ml in 8 minutes to a maximum of 7 ml
(taking about 1 hour) into each limb. Serial radiographs are taken during
injection and at intervals up to 24 hours. As the procedure is uncomfortable and
patients are often unable to lie still, it is frequently performed under general
anaesthesia. In a normal limb the injection will usually fill between five and
is superficial valved medial lymphatic vessels in the thigh as well as most of
the inguinal lymph nodes; iliac nodes fill at between 30 and 45 minutes. Deep
lymphatics, which are frequently paired and follow the deep vessels, as well as
the lateral superficial lymphatics are not usually seen except in disease. Four
main anatomic patterns of lymphatic disease are identified by
Isotope
lymphoscintigraphy. This has largely replaced contrast lymphangiography and is
used in most centres as the primary diagnostic technique.
Technique.
The patient lies supine. Radioactive
technetium-labelled antimony sulphide colloid particles (10 nm diameter) are
injected into the web space between the second and third toes (or fingers) with
a 27G needle bilaterally. This is associated with 5—10 seconds of stinging,
about which the patient must be warned. The particles are specifically taken up
by lymphatics and about 30 per cent of the tracer is absorbed in 3 hours.
Immediately after injection a gamma camera is positioned to include the inguinal
region in its upper field. During the first hour, 12 5-minute dynamic anterior
exposures are taken. The patient is requested to exercise with a foot ergometer
(to permit reproducible exercise and tracer clearance) for 5 minutes
initially and then for 1 minute out of every subsequent 5 minutes. At 1
and 3 hours, and in selected patients at 6 and 24 hours, 20-minute whole body
exposures are taken. Between exposures the patient is ambulant.
Interpretation.
In a normal leg activity ascends the anteromedial aspect of the limb.
Several lymph channels are seen in the calf but in the thigh they cannot usually
be distinguished. Normally, radioactivity first appears in the inguinal (axillary)
nodes at between 15 and 60 minutes and is symmetrical; individual nodes cannot
usually be distinguished. At 60 minutes there is only faint uptake in the liver
and bladder. At 3 hours there is intense activity over the liver and good
symmetrical uptake in inguinal, pelvic and abdominal lymph nodes; the thoracic
duct may also be seen. Most groups interpret lymphoscintigraphy qualitatively as
attempts to perform quantitative assessment have produced inconsistent results.
It is not possible to distinguish primary from secondary lymphoedema with
certainty. However, lymphoscintigraphic patterns can be correlated to some
extent with Iymphangiographic findings.
• Proximal obliteration is associated with normal uptake from the
injection site and appearance of tracer in inguinal nodes. However, there is a
failure of tracer to progress from the inguinal lymph nodes and collaterals
crossing over to other side are present.
• Lymphangectasia is associated
with abnormal collections of tracer activity indicating extravasation into the
peritoneal or pleural cavities or into viscera. Lymphocoeles and dilated lymph
channels (megalymphatics) are also seen.
Magnetic
resonance Imaging. Magnetic resonance imaging can provide clear images of
lymphatic channels and lymph nodes, and can also distinguish venous and
lymphatic disease as the cause of a swollen limb. However, it cannot at present
provide the information available from lymphoscintigraphy, and as a
cross-sectional imaging technique it appears to have little advantage over CT.
Pathological
examination. In cases where malignancy is suspected, samples of lymph nodes may
be obtained by fine needle aspiration, needle core biopsy or surgical excision.