Anatomy Flashcards
Mechanisms of spread from malignant tumours
Direct extension local spread - can happen to an extent in benign
Lymphatic spread -> occurs only in malignant
Haematogenous -> occurs only in malignant
Benign tumour … metastasise
Never
What is a malignant tumour
A tumour site not continuous with the primary tumour
Do tumours affect the surrounding area
All tumours types benign, metastasis, primary and secondary can affect the surrounding structures
Their affect depends on the structure
Pituitary a pea size tumour can have a large affect
Whereas a tumour in the abdomen can be asymptomatic for a long time due to the large space it can fill
Benign tumour typical features
Small Boundary well demarcated Well differentiated Slow growing - takes a while to develop symptoms Non invasive Non metastatic
Malignant features
Large
Poorly demarcated
Poorly differentiated
Rapidly growing
Haemorrhaging recruit blood vessels to feed it
Often veins which can break which leads to haemorrhage
Necrosis
Metastatic especially when it invades blood/lymph
Lymphatic capillaries are made of
Endothelial cells
Attachment of these cells to each other
Do not touch
They slide next to each other gaps between them allow fluid to pass through
When do they overlap
To form valves
Make it a one way system
How long does fluid sit in the capillaries for
Why
Can be a long time
No pump system or pressure dependent on surrounding structures
Arteries and veins and muscles
Ending of the tubes
Blind ending
Lumen size
Wide lumen, progressively wider 15-75 micrometers diameter
Where do lymph vessels run
In beds
Like me
Structure
Only endothelial cells and are lie veins when bigger so have little structure and become flat when empty
Superficial lump system drains
Skin
Mucous membranes
Serious lining of cavities
Hat do superficial lymph vessels drain with
Drain in parallel with veins
Deep system drains
Organs
Skeletal tissue
Muscle tissue
Where do deep vessels drain with
Parallel with para aortic nodes -> surround branches of the aorta
E.g. External and interval iliac nodes, renal nodes
Where do they drain to left side and lower abdomen and leg of the right drain
Thoracic duct
Cisterns chyli
What is the cisterna chyli
Dilated sac at the lower end of the Thoracic duct
When does the cisterns chyli receive lymph from
Intestinal trunk
The right and left lymphatic trunk and lower limbs
Where us it situated ref peritoneum
Retro peritoneal
Location cc ref vertebrae
L1 and l2
Cc contents
Milky white contents as it receives fatty chyle from intestines
It acts as a conduit for the lipid products of digestion
Location thoracic duct ref vertebrae
Second lumbar extends to the root of the neck
Where does thoracic duct drain into
Left subclavian vein where it meets internal jugular making the brachiocephalic vein
Where dies thoracic trunk collect lymph from
Intercostal left bronchiomediastinal Left subclavian and left jugular nodes All body except Right internal jugular Right subclavian nodes Right bronchiomediastinal nodes
Where does the lymph drain into that doesn’t drain into the thoracic trunk
Right subclavian vein
Mechanisms of cancer spread
Direct extension
Lymphatic spread
Haematogenous spread
What is direct extension
Local spread on adjacent tissues
Does not necessarily spread into tissues of the same system
Prostrate -> neck of the bladder
Reproductive to urinary
Lots of tissue types - epithelium through bm then mucosa then peritoneum
Lymphatic spread
Vessels and nodes
Sometimes spread stops when it reaches a lymph node but this is not reliable
Predictable can predict which nodes metastasis from different cancer will spread to
Haematogenous spread
Blood vessels
Veins especially as veins are thin walled easier for cancer to enter them
What is the metastatic cascade
1) uncontrolled division
2) transformation
3) angiogenesis
4) motility and invasion
5) embolism and circulation
6) arrest in the capillary beds
- after the heart first capillary beds they reach is the lungs
- cancer often metastasis primary mets
Passes the lungs can then form primary mets anywhere
Or primary mets in lungs can then go to pulmonary vessels get secondary mets elsewhere in the body
7) adherence
8) extravasation not organ parenchyma
9) response to micro environment
10) tumour cell orolferation and angiogenesis
11) metastasis
12) metastasis of metastasis
Direct local primary spread where to
Tumour penetrates into a natural space - subarachnoid, peritoneal, pleural
Commonly associated with seeding in body cavities - can get plaques of cancer cells known as cakes
Most common peritoneal cavity - mental cake in ct scan -> omentum good blood supply
Cancer present in smaller space will affect other structures
Small space cancer can compress other structures
In large spaces can go undetected - abdomen ovarian cancer can get very large before any abdominal problems
Site of primary tumour is important
Left, right, superior, inferior
Symptoms
Pain discomfort
E.g. Lung cancer
Sidedness Physically close to important structures Subclavian Phrenic nerve Root of neck
What happens if right sided close to midline
Compress superior vena cava Impaired venomous return Congested neck vein Finger clubbing Recurrent laryngeal Vocal cord paralysis speech impediment and breathlessness
Lymphatic secondary spread why is it the most common route
Lymph vessels have no basement membrane and veins do
So it is easier for cancer to invade lymph than veins
Are there any functional lymphatic within the tumour
No
They rely on adjacent lymphatic system
What are nodes like that have metastasis
Painless but hard full of metastatic cells
Can regional lymph nodes be effective barriers
Yes
Can destroy malignant cells
Localised
How do nodes that have metastasis treated
Removed by surgery
Chemotherapy
Are enlarged lymph nodes indicators of fully disseminated disease
Not necessarily
What is the sentinel lymph node
The first node in a regional basin to be involved - first node to receive the lymph drainage from a tumour
What happens to this sentinel node
Biopsied to help predict likely spread of the cancer
Where are lymph nodes important especially
Breast cancer
Colon cancer
Melanoma
Can cancer skip lymph nodes
Why
Yes
Occlusion or venous lymph anastomoses
Example of secondary spread breast
What is the breast
Modified sweat glands
Where does the breast lie
Within superficial fascia
Overlies pectoralis major muscle overlies ribs 2-6
Where can direct spread be to
Can spread directly to the pectoralis major and then to the thoracic cavity
What are coopers ligaments
Connective tissue in the breast that helps to maintain breast shape
How can you tell if cancer is effecting coopers ligaments
Shape of breast change
Mammograms useful not useful
Useful after the menopause not useful before
Need to use ultrasound or MRI
Due to the inc density of breast tissue at younger age
What is a lymphoscintigraphy
Nuclear medicine imaging that provides pictures of the lymph system used to identify the sentinel lymph node
Why haematogenous spread to the veins not arteries
Thin walls more easily invaded that arteries
And low pressure more likely to adhere
Cancer spread follows patter of venous drainage
Drain colon via sigmoid veins, colic veins, jejunal veins
Git to the venous portal vein here they can spread to the liver
Bone metastasis
Rare Poor prognosis Prostate Breast Lung Thyroid Usually spreads to spine
Pathological features of cancerous bone
Cancerous bone wide and very reduced density of bone
Spine involved compression
Breast cancer met to the Boone picking up shopping can cause a humerus fracture
Bone metastasis following prostate cancer
Via paravertebral veins
Mets to sacrum, lumbar spine
Pelvis first valveless veins connect prostate to paravertebral veins
Bone weakness displacement and fractures
Brain mets more or less common than primary tumour
More common
What is spread to the brain limited by
Blood brain barrier
Prognosis with brain mets
Poor due to limited space
Areas of brain most likely to have mets
Meninges Parenchyma - cerebrum 80% - brainstem 5% - cerebellum 15%
Lung mets easy or difficult to differentiate from primary tumour
Difficult
Diagnosis
Plain film and ct
Radiotherapy what does it do?
Irradiate - kills dividing cells
Can also target the skin so can cause burns
Chemotherapy
Cytotoxic drugs
Immunotherapy
Hormone therapy
Administration of cytotoxic drugs
Via hepatic artery
Surgery
Tends not to be curative
5 year survival poor
Why is surgery performed
To relieve mass effect/compression
Remove lymph nodes
Patient must be fit enough to go under - anaesthetic
