Capítulo II. Mecánica automotriz
2.5 Cuadro estadístico vehicular
• The lymphatic system develops from cystic spaces on either side of neck and groin. These large cystic spaces develop lymphatic vessels draining into them.
Box 13.4: Hodgkin’s vs non-Hodgkin’s lymphoma
Hodgkin’s lymphoma Non-Hodgkin’s lymphoma
i. Bimodal age. i. Elderly age (60-80 years).
ii. Lymph nodes commonly involved—left supraclavicular. ii. Abdominal lymph nodes.
iii. Waldeyer’s ring—rarely involved. iii. Commonly involved.
iv. Lymph node involvement—centripetal iv. Centrifugal (epitrochlear).
(mediastinal, para-aortic).
v. Extralymphatic sites—less involved. v. More commonly involved.
vi. Pattern of spread in lymph nodes—Definite pattern, vi. No definite pattern of spread in lymph nodes.
starting from cervical lymph nodes and then spreading downstream.
vii. Staging laparotomy helpful. vii. No role of staging laparotomy.
viii. Systemic symptoms (B)—more common. viii. Less common.
ix. Microscopy—RS cell present. ix. RS cells absent.
x. Prognosis—Good. x. Poor.
Box 13.5: Burkitt’s lymphoma—
differential diagnosis
• Soft tissue sarcoma
• Malignant melanoma
• T-cell lymphoma
• Metastatic skin deposits
http://dentalbooks-drbassam.blogspot.com
Diseases of Lymph Nodes and Lymphatics
137
• Abdominal lymphatic channels drain into cisterna chyli present in the retroperitoneum. The thoracic duct originates from upper cisterna chyli just below the diaphragm, passes through posterior media-stinum and ends in left internal jugular vein in the neck.
• Lymphatics accompany veins everywhere except in cortical bones and central nervous system.
Physiology of Lymphatic System
• The main function of lymphatic system is to return lymph (protein rich fluid) from the interstitial space to back into circulation.
• About 3 liters of interstitial fluid is returned to circulation each day through lymphatics.
• The lymphatic system also allows lymphocytes to pass from lymph nodes to bloodstream.
• Lymphatic capillaries have large pores between endothelial cells that allow macromolecules to cross the wall.
Acute Lymphangitis
It is caused by Streptococcus pyogenes infection. It presents as reddish blue streaks in the skin involving area between the site of infection and draining lymph node group. Treatment is bed rest, limb elevation, antibiotics (cloxacillin).
Lymphedema
• It is excessive accumulation of tissue fluid in the extracellular space due to defective lymphatic drainage.
• Commonest site is lower limbs. Other sites are scrotum, penis and upper limbs.
Primary Lymphedema
The cause is unknown and considered to be congenital.
Women are affected three times more than men. It is further subdivided into various types:
a. On basis of age at presentation
• Congenital: It presents before 2 years of age. If it is familial, it is called as Milroy’s disease.
• Praecox: It presents at 2-35 years of age.
• Tarda: It presents after 35 years of age.
b. On basis of lymphangiographic findings
• Aplasia: There is complete absence of lymphatic trunks and the swelling is present from birth.
• Hypoplasia: The lymphatic trunks are fewer and smaller than usual. It is commonest variety. The swelling starts in early adult life after an attack of cellulitis.
• Hyperplasia: The lymphatics are enlarged, increa-sed in number and tortuous (similar to varicose veins). The patient presents with discharging vesicles of milky fluid due to incompetent valves.
Secondary Lymphedema
It is much more common than primary form. There is destruction or obstruction of lymphatics due to some underlying cause.
• Filariasis: It is commonest cause of lymphedema worldwide. It is caused by Wuchereria bancrofti worm that enters the circulation by mosquito bite. It then enters the lymphatics and produces fibrotic inflammatory reaction in the lymph nodes. Initially, patient presents with high grade fever and chills, lymphangitis and epididymo-orchitis. Later, due to obstruction of lymphatic pathway, there is gross swelling of lower limb (elephantiasis) (Fig. 13.8).
Hydrocele is a common manifestation.
The diagnosis is made by demonstration of microfilariae in peripheral blood film prepared during early morning.
Differential leukocyte count shows eosinophilia.
Complement fixation test may be positive.
Fig. 13.8: Elephantiasis left leg
http://dentalbooks-drbassam.blogspot.com
138
Textbook of Surgery for Dental StudentsTreatment is with diethyl carbamazine.
• Malignant deposits: It could be primary (lymphoma) or secondaries in the lymph nodes causing lymphatic obstruction.
• Following radiotherapy and surgical removal of regional lymph nodes for the treatment of cancer (most commonly of the breast) (Fig. 13.9).
• Trauma causing lymphatic disruption and venous thrombosis (e.g. degloving injuries).
• Chronic infections causing lymphangitis and lymphadenitis, e.g. tuberculosis.
Differential diagnosis of lymphedema: It is shown in Box 13.6.
Lipedema is bilateral symmetrical enlargement of legs due to deposition of abnormal fat. The feet are not involved. It almost exclusively affects women near puberty.
Clinical Features of Lymphedema
• Gradual swelling of one or both lower limbs.
• Limb size increases during the day and decreases at night but is never normal.
• Edema is pitting in early stage but becomes nonpitting in chronic stage due to subcutaneous tissue thickening.
• In long standing cases, skin becomes hyperkeratotic and fissured (pachydermatous appearance).
• Skin vesicles discharging milky fluid may be present.
• Skin infection in form of erythema and cellulitis may be present
• The patient should also be examined for:
Upper extremity lymphedema
Genital lymphedema
Hydrocele
Chylous ascites
Chylothorax.
Investigations
The diagnosis of lymphedema is essentially clinical.
Investigations may be required to confirm the diagnosis in atypical and doubtful cases and to decide the type of surgical treatment.
Lymphangiography: Patent blue dye is injected in the web space to identify lymphatics. These lymphatics are cannulated and lipid soluble dye is injected into the lymphatics. The lymphatics are visualized as parallel tracks of uniform size that bifurcate as they proceed proximally. This test is ‘gold standard’ for showing structural abnormalities of larger lymphatics and lymph nodes. It is valuable if lymphatic bypass is considered.
However, this test is technically difficult, may damage remaining lymphatics and requires general anesthesia.
Hence, it has become obsolete as a routine method of investigation.
Isotope lymphoscintigraphy: It is most commonly used screening investigation and can be performed as out patient procedure. Radioactive technetium labeled colloid particles are injected subcutaneously in web space. These are taken up by lymphatics and pass Fig. 13.9: Lymphedema left arm and shoulder after
mastectomy for carcinoma breast
Box: 13.6: Differential diagnosis of lymphedema
http://dentalbooks-drbassam.blogspot.com
Diseases of Lymph Nodes and Lymphatics
139
proximally to lymph nodes. Using gamma camera, radioactivity is measured at different time points.
Proximal obstruction causes delay in progress of radioisotope.
CT scan and MRI imaging of the limb can help to differentiate lymphedema, venous edema and lipedema.
Pathological examination: FNAC or lymph node biopsy of enlarged lymph node can tell about underlying pathology (malignancy, tuberculosis, etc.).
Treatment
Conservative treatment:
• Limb elevation to reduce the edema.
• Graduated compression garments with maximum pressure at ankle and decreasing toward groin.
• Intermittent limb compression with pneumatic massaging device. It encourages interstitial fluid movement out of subcutaneous tissues.
• Weight reduction and exercise.
• Care of foot to prevent infections.
• Antibiotics for skin infections.
• Benzpyrones reduce edema by improving micro-circulation and exert anti-inflammatory effect.
• Diuretics have no role.
Surgical treatment: It is not indicated for cosmetic reasons. It is performed only in a few patients to improve functions.
a. Bypass procedures: These are performed in case of lymphatic obstruction seen on lymphangiography.
The procedures can be:
• Anastomosis between lymph node and vein.
• Lymphovenous anastomosis.
Fig. 13.10: Cut section image of Thompson procedure b. Debulking procedures:
• Sistrunk procedure: A large wedge of skin and subcutaneous tissue is excised and the wound closed primarily. This procedure is no longer used.
• Thompson procedure (Swiss roll operation):
Flaps of skin are de-epithelized and then buried in subfascial plane so that lymph will drain through skin lymphatics to deep fascial compart-ment. The procedure is largely abandoned due to poor results and complication of pilonidal sinus formation (Fig. 13.10).
• Homans’ procedure: Skin flaps are raised, subcutaneous tissue is excised, flaps are trimmed and wound closed primarily. It can be performed only if skin is healthy.
• Charle’s procedure: The skin and subcutaneous tissue are excised circumferentially down-to-deep fascia. Split skin grafts are then applied over the deep fascia. This procedure is useful in patients with unhealthy skin.