Pathology - Bone Pain Flashcards
What are metabolic bone disorders
Altered Ca or phosphate or disordered homeostasis
Primary osteoporosis
Senile OP
Post-menopausal OP
Secondary OP
Endocrine disorders e.g. hypeyerparathyroidism
GI disorders e.g. malnutrition
Drugs e.g. corticosteroids
Pathogenesis of OP
Age-related changes Reduced physical activity Genetic factors Ca nutritional status Hormonal influences
Age related changes leading to OP
Osteoblasts in older people have reduced proliferative and biosynthetic availability and don’t respond to growth factors as well as they used to
Reduced physical activity leading to OP
Mechanical factors stimulate normal bone remodelling
Hormonal influences leading to OP
Oestrogen deficiency after menopause increases secretions of infl cytokines —> osteoclast recruitment and activation
Complications of OP fractures
Fractures
PE - DVT due to lack of movement after fracture
Pneumonia
Non-skeletal effects of infl
Induction of immune cell differentiation and enhanced infl
Inhibition of tumour cell proliferation, induces differentiation and inhibits angiogenesis
What is cancer caused by
DNA mutations either induced by exposure to mutagens or spontaneously
Hallmarks of cancer
Sustaining proliferative signalling Evading growth suppressors Resisting cell death Enabling replicative immortality Inducing angiogenesis Reprogramming energy metabolism Evading immune destruction Activating invasion/ metastasis
What causes the hallmarks of cancers
Underlying genome instability causing genetic diversity
Tumour microenvironment
Normal cells recruited by the tumour cells to help the development of these hallmark traits
Oncogene categories
Growth factors or growth factor receptors – these induce cell growth
Signal transducers – relay receptor activation to the nucleus
Nuclear regulators
Cell cycle regulators
Regulators of apoptosis
Prevent apoptosis in normal cells and promote it when mutated cells have DNA that cant be released
BCL2
BCL2
Normally stabilises the mitochondrial membrane blocking release of cytochrome c but can be disrupted by malignant cells
Why do cancers upregylate telomerase
Telomeres normally shorten w/ serial cell divisions, eventually causing cell senescence
Angiogenic factors produced by cancers
FGF and VEGF
New blood vessel formation is needed for tumour survival and growth
Dysplasia
Disordersed cell growth
Theoretically reversible w/ alleviation of the inciting stress
If stress persists, dysplasia can progress to carcinoma (irreversible)
Neoplasia
Growth that is unregulated, clonal and irreversible
What causes neoplasia
The autonomous/ relatively autonomous abnormal growth of cells that persists in the absence of the initiating stimulus
Characteristics of benign tumours
Remain localised
Slow growing
Closely resemble tissue from which they arise
Often circumscribed or encapsulated
Characteristics of malignant tumours
Invade the surrounding tissues and many have the capacity to metastasize
Often rapidly growing
Vary in their resemblance to the tissue of origin
Usually have an irregular margin
In-stu carcinoma vs invasive carcinoma
In situs carcinomas are epithelial neoplasms exhibiting all of the cellular features associated w/ malignancy, but which has not yet invaded through the epithelial basement membrane
Routes of metastasis
Blood vessels
Lymphatics
Recognising malignant cells
Increased nuclear to cytoplasmic ration
Nuclear pleomorphism and hyperchromasia
Irregular chromatin distribution within the nucleus +/- prominent nucleoli
Irregular nuclear membrane
Recognising benign cells
Low nuclear to cytoplasmic ratio
All nuclei of similar size and not hyperchromatic
Vesicular, evenly distributed chromatin
Smooth nuclear membranes
Tumour classification
Histogenetic classification; named after tissue/ cell of origin
Tumour grading
How closely the tumour resembles the tissue from which is arises (differentiated)
Indicator of how aggressive the tumour is likely to be
Grade 1 tumours are well differentiated and closely resemble the origin tissue, but Grade 3 tumours do not
The higher the tumour grade…
The worse the prognosis
Factors influencing tumour invasion
Decreased cell adhesion – cells must be able to separate and disperse integrin receptors allowing tumour cell matric adhesion
Secretion of proteolytic enzymes – to enter vessels
Increased cell motility
Steps of tumour invasion of the basement membrane
Loosening of intercellular junctions due to loss of cadherins (down regulated) and increased expression/ distribution of integrins
Degradation of the extracellular matrix due to proteolytic enzymes
Migration and invasion – cleavage of basement membrane proteins generate molecules that bind to receptors on tumour cells and stimulates locomotion
What do we see in tumour associated fibroblasts
Altered expression of genes that encode extracellular matrix molecules, proteases, protease inhibitors and growth factors
Metastasis
Process whereby malignant tumours spreads from the site of origin (1’ tumours) to form other tumours (2’ tumours) at distant sites.
Carcinomatosis
Describes extensive metastatic carcinoma.
What must cells be able to do to metastasise
Detach tumour cells from the neighbours
Invade the connective tissue to reach lymphatics and blood vessels
Intravasate into the lumen of vessels
Evade host defence mechanism e.g. NK cells and T lymphocytes
Adhere to endothelium as a remote location
Extravasate the cells of the vessel lumen into the tissue
Survive and grow in the new environment
Seed and soil hypothesis
Primary tumour
Proliferation/ angiogenesis
Detachment/ invasion Embolism/ circulation
Transport
Arrest in organs
Adherence to vessel wall
Extravasation and establishment of a microenvironment
Proliferation/ angiogenesis –> metastasis
What does detachment/ invasion include
Lymphatics
Venules
Capillaries
What does embolism/ circulation
Interaction w/ platelets, lymphocytes and other blood components
Different routes of metastasis
Lymphatic - more typical of carcinoma
Haematogenous - more typical of sarcoma
Transcoelemic
Lymphatic metastasis
Tumour cells travel through afferent lymphatics to enter lymph nodes
Cause lymph nodes to enlarge and become firm
May extend lymph node and causes adherence
Interrupts lymphatic flow
Which part of the lymph nodes do tumour cells travel to
Subcapsular sinus
Transcoelemic metastasis
Metastasis to the peritoneal, pleural and pericardial cavities
Can cause ascites
How do tumours evade the immune system
Destruction by selection of antigen negative clones
Loss of MHC molecules
Expression of transforming growth factor beta or PD1 ligands by the tumour cells
Tumour staging
Extent of tumour staging
TMN
TMN
T - primary tumour, suffixed by number denoting size, or anatomical extent
N - lymph node spread, suffixed by number denoting no. lymph nodes or group of lymph nodes containing metastases
M: anatomical extent of distant metastases
When are clinical effects of tumours inconsequential
If the organ is large relative to the size of the tumour and no vital structure is threatened
Local effects of tumours
Destruction
Displacement
Compression
Metabolic effects of tumours
Well-differentiated tumours retain the functional properties of the parent cell e.g. hormone production
When can paraneoplastic syndromes result
I§nappropriate secretion of a hormone by a tumour that does not normally secrete the hormone.
Systemic effects of cancer
Cachexia Warburg effect Neuropathy Myopathy Venus thrombosis Glomerular
Cachexia
Severe wt loss and debility in a cover pt
Warburg effect
Cancer cells have a high rate of glycolysis with formation of lactic acid as opposed to pyruvate in normal cells
Mortality associated with neoplasia in lungs
Bronchopneumonia
Mortality associated with neoplasia in bone
Hypercalcaemia –> renal failure and cardiac arrhythmias
Mortality associated with neoplasia in liver
Electrolyte abnormalities
Mortality associated with neoplasia in blood vessels
Haemorrhage or vessel obstruction –> heart failure
Mortality associated with neoplasia in brain
Raised intracranial pressure, compressing respiratory centre in brainstem
Mortality associated with neoplasia in GI tract
Obstruction → impair nutrition, ulceration/ perforation
TMN - T
Tubule formation
The extent to which the tumour forms tubules
TMN - T scores
1: >75% of tumour
2: 10-75% of tumour
3: <10% of tumour
TMN - N
Nuclear pleomorphism
The size of the nuclei in the cells of the tumour compared to normal nuclei
TMN - N scores
1: Similar in size to benign epithelial cells
2: 1.5 - 2x size of benign epithelia; cells
3: >2x size of benign epithelial cells
TMN - M
Mitotic count
How rapidly cells are dividing (depends on microscope field diameter)
TMN - M scores
1: Low count (per 10 high power fields)
2: Intermediate count
3: High count
Grade 1 tumour scores
Total score 3-5
Grade 2 tumour scores
Total score 6-7
Grade 3 tumour scores
Total 8-9