Classification of insufficiency
In pathological anatomy, three main types of lymphatic system insufficiency are distinguished:
- Mechanical: occurs when there are obstacles (organic or functional) in the path of lymph flow.
- Dynamic: develops when the volume of tissue fluid exceeds the carrying capacity of lymphatic vessels, often due to high capillary permeability.
- Resorptive: caused by a decrease in the ability of lymphatic capillaries to absorb fluid or changes in the properties of tissue proteins.
Causes and mechanisms of lymph stasis
Lymph stasis refers to the cessation of lymph flow. The main causes include:
- Vascular obstruction (tumor metastases, parasites, siderophages).
- Compression of lymphatic pathways from the outside (tumors).
- Iatrogenic factors (lymph node dissection).
- Spasm of collectors and venous congestion.
In general venous congestion, the pressure gradient between the lymph and blood in the thoracic duct is disrupted, which hinders lymph drainage from organs and tissues.
Morphological consequences
Prolonged lymph stasis leads to a number of serious changes:
- Lymphedema: development of lymphatic edema.
- Cavitary disorders: chylosis (chylothorax, chylous ascites) and formation of chylous cysts.
- Vascular changes: lymphangiectasia, formation of lymphovenous shunts and lymph thrombi.
- Tissue changes: in chronic processes, fibroblasts are activated, leading to sclerosis and the development of elephantiasis.
Briefly: answers to topical questions
What types of parasites cause obstruction of lymphatic vessels?
Obstruction of lymphatic vessels is caused by parasitic roundworms — nematodes.
- Filariae are the causative agents of lymphogenic filariasis (tropical infestation). Adult parasites localize in lymphatic vessels and block lymphatic pathways. This causes reactive inflammation and sclerosis of the lymphatic system, which subsequently leads to lymphadenitis, blockade of lymph drainage, and the development of elephantiasis (elephantiasis).
What cellular and biochemical processes underlie the pathogenesis of elephantiasis?
The pathogenesis of elephantiasis (elephantiasis) is based on the accumulation of tissue proteins and the activation of fibroblasts.
Impaired lymph drainage leads to an increase in interstitial fluid pressure. Water and electrolytes partially return to the capillaries, but proteins are retained in the interstitium. The accumulation of proteins retains water due to oncotic pressure, forming a vicious circle. Chronic lymph stasis stimulates fibroblasts, leading to massive sclerosis and irreversible fibrotic changes in the skin and subcutaneous tissue.
How does chylous fluid in chylothorax differ from venous transudate?
Chylous fluid in chylothorax is an accumulation of chyle (lymph) and has a milky-white color. Transudate on ultrasound is usually anechoic (echo-free).
M-D-R: Mechanical (obstruction), Dynamic (fluid excess), Resorptive (poor absorption).
Class and exam questions
What is the difference between mechanical and dynamic insufficiency?
Mechanical insufficiency is caused by a physical obstacle to lymph flow, whereas dynamic insufficiency is caused by a mismatch between the excessive volume of tissue fluid and the rate of its drainage.
Why is lymph circulation impaired in venous congestion?
Increased pressure in the venous system reduces the pressure gradient between lymph and blood, which is critical for normal lymph drainage from the thoracic duct.
What does chronic lymph stasis lead to?
Chronic lymph stasis activates fibroblasts, causing tissue atrophy and sclerosis, which can ultimately lead to elephantiasis.
What else to study on this topic
- Pathogenesis of lymph thrombi and their difference from hematogenous ones.
- Mechanisms of development of chylous ascites in thoracic duct obstruction.
- The role of siderophages in lymph node blockade.
- Differential diagnosis of lymphedema and venous edema.
- The relationship of lymphovenous shunts with the body's compensatory mechanisms.
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