The lymphatic system Flashcards
What is the lymphatic system made up of?
Blind ending capillaries and lymph nodes which return lymph to the venous system.
Do the capillaries have valves? How fast is the flow?
Yes but retrograde flow can still occur. Fluid travels slowly through the 15-75 micrometre capillaries
What does the superficial system drain and where to?
Skin
Mucus membrane
Serous linings of cavities
Drains in parallel with veins.
What does the superficial system drain an where to?
Drains organs in parallel with arteries to the para-aortic nodes
Where does all the system drain to?
Superficial joins deep and drain into cysterna chyli and thoracic duct which joins the SCV.
How much fluid travels through the system a day?
8L.day at a low pressure
What does the cysterna chyli drain?
Lower limbs, R+L lumbar and intestinal trunks
What drains into the Left thoracic duct?
Cysterna chyli, L intercostal, L bronchomediastinal, L subclavian and L jugular drainage
Where does the left thoracic duct ultimately drain to?
L SCV
What does the R thoracic duct drain?
R subclavian, jugular trunk, bronchomediastinal nodes into the R SCV.
What imaging method is used to view the lymphatic system?
Lymphangiogram
Where do the posterior intercostal vessels lie?
Posterior to the diaphragm
What is the issue with benign tumours?
They do not metastasise but the cause pressure on local structures
What can tumours erode through?
Membranes and compartments into cavities
What are the characteristics of a benign tumour?
Small, well differentiated and demarcated, slow growing, non-invasive and non-metastasising
What are the characteristics of a malignant tumour?
Large, Poorly differentiated and demarcated, rapidly growing, haemorrhage, necrosis, locally invasive and metastasising.
How can cancer spread?
- Locally through direct extension into adjacent tissues and cavities.
- Lymphatic spread through vessels and nodes in a predictable manner.
- Haematogenous spread, particularly through veins.
- Metastatic cascade
Why do secondary tumours have some appearance of the primary tumour?
Cells have memory
What causes a primary tumour in the neurocranium?
CT and glial cells.
Can’t get a primary cancer of neurons in the brain
How does local spread occur?
Penetration into natural space through BM. Associate with SEEDING in cavities.
Which is the most common cavity for seeding?
Peritoneal due to large size, large volume of epithelial tissue and good blood supply.
What results from seeding in the peritoneal cavity?
Omental cake appearance on CT
ASCITES as increased fluid in cavity, causing discomfort from the raised pressure.
What is seeding?
The spread of cancer cells to neighbouring tissues and their subsequent growth as a malignancy, usually caused by a biopsy.
How do ovarian cancer pts present?
Unmovable weight gain and hard abdomen.
What are the implications of lung cancer on local structures?
Cause veins to collapse = CV symptoms
Compress sympathetic chain, SCV and SVC
Why does lung cancer grow well?
High O2 and can easily invade the spongy lung tissue
Why does a tumour of the maxillary sinus grow fast?
Due to the space and O2 supply. Affects young males most.
Where will a tumour of the maxillary sinus spread to and what will this cause?
Paranasal sinuses = blocked nose
Alveolar bone = toothache
Orbit = double vision (spreads by fracturing the orbit floor that lies above maxillary sinus)
What does pressure on the Recurrent laryngeal nerve cause?
Vocal cord paralysis affecting voice and breathing
Why might clubbing arise from a tumour on the right side of the midline of the thorax?
Pressure on SVC impairs return to R atrium and causes congested neck veins
How does cancer spread through lymphatics?
Tumours have no lymphatic drainage so rely on adjacent systems. Can skip nodes due to occlusion or venous-lymph anastomoses.
Why is the predictable pattern of lymphatic spread important?
Determines prognosis, treatment and what needs removing
Why are regional nodes important?
They can act as barriers to destroy the malignant cells via immunological responses
What happens when an immunological response takes place in a node?
Localised hyperplasia
What does an enlarged node signify?
Hard and hurts = infection
Dense and painless - malignant
What is the sentinel node?
The first node in a regional basin to be involved in the spread. A biopsy of this node helps to predict spread.
How does a) breast b) melanoma and c) colon cancer spread through the lymphatic system?
a) Breast = superficial with veins
b) Melanoma = superficial with veins
c) Colon = Deep
What increased a males risk of breast cancer?
Gynaecomastia and use of steroids
Where is the breast located?
It is a modified sweat gland that lies within the superficial fascia over pectoralis major, ribs 2-6 and cooper’s ligaments.
What anatomical relations is it important to consider in breast cancer?
Near midline
Has an axillary tail
The centre of the breast is midclavicular
Which women are more at risk of breast cancer?
Nullipara women. Glands are small until lactation and surrounded by fat and CT.
More aggressive in younger women than postmenopausal
What is the lateral blood supply of the breast?
Axillary A and V
What is the medial blood supply to the breast?
Internal thoracic A and V / Mammary A
Intercostal branches
What is the lymphatic drainage of the breast?
Follows veins
Where does breast cancer spread and metastasis to?
Axilla, abdomen, bone and contralateral breast. Spreads locally through thoracic wall
What may result from surgical removal of breast cancer?
Surgical oedema if the lymphatic drainage is removed
Why is haematogenous spread more common in veins?
The walls are thinner and so more easily invaded.
Which veins allow easy access to arterioles?
Pulmonary veins
What type of drainage does the liver receive?
Portal drainage = access to capillary beds. Liver metastasis common
How does lung cancer spread through vessels?
Easy access into the thin walled arterioles
Where does the vertebral column drain to?
Paravertebral venous plexus
Where does the colon drain to?
Ascending and transverse via SMV and transverse and descending and sigmoig via IMV to the liver via PORTAL drainage.
How does prostate cancer spread?
Via paravertebral veins to sacrum, vertebrae, pelvis
Which cancers commonly metastasise in bone?
Prostate, breast, lung and thyroid
How does bone metastasis present?
Pain
Increased blood calcium
Spinal cord compression as spreads to spine
Causes pathological fractures
Where do brain metastasis occur?
Access is limited by BBB but can spreead to meninges, parenchyma, cerebrum, brainstem, cerebellum. Metastasis are more common than primary brain tumours.
Where does lung cancer spread to? How does this present?
Mediastinum and hilar = CV symptoms present first and then pleural effusion which will then cause respiratory symptoms
What are the three main types of intervention?
- Radiotherapy = Irradiate tumour and minimises damage to normal tissue. Damages skin superficial to tumour with a 3rd degree burn.
- Chemotherapy = cytotoxic, hormonal, immunotherapy. Administered via veins but need to be fit and healthy for chemo
- Surgery to relieve symptomology of compression and to remove lymph nodes. May be curative but risk of returning if micro cells left behind.
