Lymphatic system

 

Tissues where lymphocytes are found

 

Primary organs

Bone marrow, all lymphocytes derive from stem cells in bone marrow

Thymus gland, stem cells migrate from bone marrow, T lymphocytes mature here.

 

Secondary organs

Organs and tissues which contain concentrated collections of B and T lymphocytes

 

Other areas of lymphoid tissue

Spleen – largest mass of lymphoid rtissue

Mucosa associated lymphoid tissue (MALT), tonsils, Peyer’s patches in small intestine, appendix, respiratory and urogenital mucosa

No lymphatic capillaries in brain, bone marrow, epithelia, cartilage

 

Basic functions

Drainage of excess fluid from tissues

Protection from foreign invaders

Movement of lymph throughout the body

Removal of impurities by filtration and phagocytosis

Storage of lymphocytes

Absorption of fats from small intestine

Lymphatic tissue has good powers of regeneration

 

Tissue fluid formation

32 mmHg at arterial end

15 mmHg at venous end

26 mmHg colloid osmotic pressure

90% of tissue fluid is reabsorbed

 

Lymphatic capillaries

Wider than blood capillaries

Incomplete or absent basement membrane

Blind ended

Flappy cells act as valves

Limited basement membrane

Anchoring filaments connect to surrounding connective tissues

Drain 10% of tissue fluid

Radial traction

So when interstitial pressure increases, the lymphatic capillaries are not compressed, (which would reduce lymphatic drainage) but pulled open, increasing the gaps between endothelial cells.

Endothelial cells are contractile.

First a lymphatic capillary is actively or passively compressed. As it dilated the pressure is lowered, and tissue fluid is sucked in.

 

Structures

Capillaries

Afferent lymphatic vessels

Lymph nodes

Efferent lymphatic vessels

Lymphatic trunks

Lacteals - chyle

Right lymphatic duct - upper right part of body

Left Thoracic duct    - remainder of body

 

Right lymphatic duct is 1.2 cm

Left thoracic duct begins in chyle cistern, or cisterna chyli (L1-L2) is about 40cm long and 0.5 cm wide. This is the confluence of the 4 major abdominal trunks.

 

Movement of lymphatic fluid

Contraction of lymphatic vessel walls

Endothelial cells are contractile, larger vessels have contractile cells, similar to smooth muscles.

Larger vessels have smooth muscles in their walls for contractility

Vessels contain more valves than veins

Valves ensure one way flow in contractile vessels

Fluid moves from one valvular space to the next

Skeletal muscle contraction

Adjacent arterial pulse

Respiratory pump

10 to 50 fold increase possible

Pressures 2-3mmHg in capillaries, 10-20mmHg during contraction of larger vessels

 

Lymph nodes

450

0.1 – 2.5 cm

Collagen based reticulum

Lymphoid tissue

Lymphocytes and macrophages

Filtration

Defence

Antigen presentation

Lymphocyte proliferation

Fluid percolates through a series of nodes

 

Lymph node sites

Pericranial

Cervical

Axillary

Tracheal

Deep

Inguinal

Femoral

 

Lymphatic fluid

Lymph

Clear colourless fluid

3 litres / day

Water and electrolytes

Cell debris

Chyle - chylomicrons

Proteins

Bacteria

Viruses

Malignant cells

 

Order of fluid flow

Plasma

Tissue (interstitial) fluid

Lymphatic capillaries

Afferent lymphatic vessels

Lymph nodes

Efferent lymphatic vessels

Lymphatic trunks

Lymphatic ducts

Junction of internal jugular and subclavian vein

Plasma

 

Disorders

Lymphadenopathy

Lymphangitis - tracking

 

 

Causes of oedema

 

Increased capillary pressure

Venous hypertension

Venous insufficiency

Heart failure

 

Decreased plasma protein

Malnutrition

Malabsorption

Nephrotic syndrome

Liver failure

 

Reduced lymphatic drainage

Nematode worms cause filariasis

Tumours

Radiotherapy stimulates fibrosis

Surgical excision

 

Increased capillary permeability

Inflammation

Sepsis

Allergic reactions

 

Exudate – protein rich fluid

Transudate – protein poor fluid

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Lymphoedema

 

When a lymphatic abnormality has been identified

Lymphatic obstruction

Excessive accumulation of tissue fluid (lymph) as a result of defective lymphatic drainage.

High protein oedema

 

Effected areas

Legs (80%)

Arms

Genitals

Face

 

Clinical features

A heavy swollen limb

Pitting oedema

Skin creases

Chronic low grade dermatitis

Pain

Reduced function and mobility

Elephantiasis

 

Evolution

Oedema, initially reduced overnight, pitting

Tissues harden due to fibrous tissue

No pitting in later stages

Loss of skin elasticity, dry skin

Chronic dermatitis

 

Complications

Infection / cellulitis, damaged fibrosed lymphatics and high protein oedema inhibits macrophages

Delayed presentation of systemic features of infection

Local immuno-compromise

Regional immuno-compromise

Increased risk of fungal and bacterial infection

Dry skin

Hyperkeratosis

Papillomatosis, lymphangioma first (cobblestone appearance)

Lymphangiectasis, dilated skin lymphatics

Lymphorrhoea

Shape distortion

DVT and post-thrombotic syndrome

 

Prevalence

500 million worldwide

2% in UK

 

Aetiology

 

Primary

Genetic

Milroy’s disease in children

Aplasia – absence of lymphatics

Hypoplasia – reduced number of lymphatics

Megalymphatics – dilated vessels

Congenital problems may present in later life

 

Secondary

Acquired due to lymphatic or node fibrosis

Cellulitis one episode or each episode of cellulitis will progressively damage the lymphatics

Cancer

Lymphatic malignancy

Radiotherapy

Surgical nodectomy

Surgical trauma

Ongoing inflammatory swelling of vessels or nodes

Chronic oedema

Obesity

Filariasis

Aetiology may be mixed with venous

 

Assessment / Diagnosis

History

Cause

Any cancer present

Any arterial or venous disease

Unilateral or bilateral

Consider multiple aetiology

Comparison with other limb

Serial circumference measurements

Measures limb volume

Exclusion of other pathology, allergic, infection

 

Differential diagnosis

Bilateral

Chronic venous hypertension

Right heart failure

Renal failure

Liver failure

Hypoproteinaemia

Limb dependency

Allergic / infection

Lipoedema, abnormal adipocytes distribution, puckering, painful fat syndrome, may go on to develop lymphoedema.

 

Unilateral

Cancer

DVT

CVH

Arthritis

 

Management

Skin care, emollients

Prevent skin and tissue changes

Complex Decongestive therapy

Compression

Short stretch multi layer bandaging

Gradated pressure profile

Don’t forget the toes

Hosiery

Exercise

Deep breathing

Manual lymphatic drainage works transferring fluid to areas drained by functional nodes.

Early treatment of infections, e.g. cellulites

Pneumatic compression therapy

Flavonoids

Albendazole for filariasis

 

 

 

 

 

 

Tissue fluid formation

32 mmHg at arterial end

15 mmHg at venous end

26 mmHg colloid osmotic pressure

90% of tissue fluid is reabsorbed

 

Primary organs

Bone marrow

Thymus gland

 

Secondary organs

Collections of B and T lymphocytes

Spleen

Mucosa associated lymphoid tissue

MALT

Tonsils

Peyer’s patches

Appendix

Respiratory mucosa

Urogenital mucosa

None in brain, bone marrow, epithelia, cartilage

 

Basic functions

Drainage

Protection

Movement of lymph

Filtration and phagocytosis

Storage of lymphocytes

Absorption of fats

 

Lymphatic capillaries

Blind ended

Flappy cells act as valves

Wider than blood capillaries

Limited basement membrane

Anchoring filaments

 

Structures

Capillaries

Afferent lymphatic vessels

Lymph nodes

Efferent lymphatic vessels

Lymphatic trunks

Lacteals - chyle

Right lymphatic duct is 1.2 cm

Left thoracic duct begins in cisterna chyli (L1-L2) is about 40cm long and 0.5 cm wide

 

Movement of lymphatic fluid

Contraction vessel walls

Skeletal muscle contraction

Adjacent arterial pulse

Respiratory pump

Valves

10 to 50 fold increase

 

Lymph nodes

450 nodes, 0.1 – 2.5 cm

Reticulum

Lymphoid tissue

Lymphocytes and macrophages

Filtration

Defence

Antigen presentation

Lymphocyte proliferation

Fluid percolates through a series of nodes

 

Lymph node sites

Pericranial

Cervical

Axillary

Tracheal

Deep

Inguinal

Femoral

 

Lymphatic fluid

Lymph

Clear colourless fluid

3 litres / day

Water and electrolytes

Cell debris

Chyle - chylomicrons

Proteins

Bacteria

Viruses

Malignant cells

 

Order of fluid flow

Plasma

Tissue (interstitial) fluid

Lymphatic capillaries

Afferent lymphatic vessels

Lymph nodes

Efferent lymphatic vessels

Lymphatic trunks

Lymphatic ducts

Internal jugular and subclavian

Plasma

 

Disorders

Lymphadenopathy

Lymphangitis

 

Causes of oedema

Increased capillary pressure

Venous hypertension

Venous insufficiency

Heart failure

 

Decreased plasma protein

Malnutrition

Malabsorption

Nephrotic syndrome

Liver failure

 

Reduced lymphatic drainage

Primary

Nematode worms - filariasis

Tumours

Radiotherapy stimulates fibrosis

Surgical excision

 

Increased capillary permeability

Inflammation

Sepsis

Allergic reactions

 

 

 

Lymphatic abnormality

 

Obstruction

 

Excess tissue fluid

 

High protein oedema

 

 

Effected areas

 

Legs (80%)

 

Arms

 

Genitals

 

Face

 

Clinical features

 

Heavy swollen limb

 

Pitting oedema

 

Skin creases

 

Low grade dermatitis

 

Pain

 

Reduced function

 

Elephantiasis

 

 

 

 

Evolution

 

Oedema

 

Tissues harden

 

No pitting

 

Loss of skin elasticity

 

Dry skin

 

Chronic dermatitis

 

 

 

 

 

Complications

 

Infection / cellulitis

 

Dry skin

 

Hyperkeratosis

 

Papillomatosis

 

Lymphorrhoea

 

Shape distortion

 

DVT

 

Prevalence

 

500 million    2% in UK

 

Aetiology

 

Primary

 

Genetic

 

Milroy’s

 

Aplasia

 

Hypoplasia 

 

Congenital

 

 

 

 

 

Secondary

 

Lymphatic or node fibrosis

 

Cellulitis

 

Chronic oedema

 

Obesity

 

Cancer

 

Lymphatic malignancy

 

Radiotherapy

 

Nodectomy

 

Surgical trauma

 

Filariasis

 

Mixed aetiology

 

 

 

 

 

 

 

 

 

 

 

 

Assessment / Diagnosis

 

History

 

Cause

 

Any cancer present?

 

Any vascular disease?

 

Unilateral or bilateral?

 

Compare limbs

 

Limb circumference

 

Limb volume

 

 

Differential diagnosis

 

Bilateral

 

Chronic venous hypertension

 

Right heart failure

 

Renal failure

 

Liver failure

 

Hypoproteinaemia

 

Limb dependency

 

Allergic / infection

 

Lipoedema

Unilateral

 

Cancer

 

DVT

 

CVH

 

Arthritis

 

 

 

 

 

 

 

 

Management

 

Skin care

 

Prevent skin and tissue changes

 

Decongestive therapy

 

Compression

 

Short stretch multi layer

 

Graduated pressure profile

 

Toes

 

Hosiery

 

Exercise

 

Deep breathing

 

Manual lymphatic drainage

 

Early treatment of infections

 

Flavonoids

 

Albendazole for filariasis