18 - Characteristics of Tumours Flashcards
Histogenic classification
Classification of the tumour by the specific cell or tissue of origin
Epithelial cell tumours
Carcinomas
Connective tissue tumours
Sarcomas
Lymphoid
Haematopoietic organs
Lymphomas/leukaemias
Characterising tumours
Differentiation
Rate of growth
Local invasion
Metastasis
Malignant tumours vs benign tumours growth wise
malignant tumours tend to grow more rapidly than benign tumours but many exceptions to this
differentiation definition
the extent that neoplastic cells resemble the corresponding normal parenchymal cells, morphologically and functionally
benign tumour differentiation
usually well-differentiated and mitoses are rare
malignant neoplasm differentiation
wide-range of parenchymal differentiation where most exhibit morphological alterations
anaplasia
neoplasms comprised of poorly-differentiated cells are described as anaplastic
differentiation - morphological changes
pleomorphism abnormal nuclear morphology mitoses loss of polarity other changes
pleomorphism
variation in size or shape
differentiation in abnormal cells
nuclear appear too large e.g. nuclear:cytoplasm ratio of 1:1 vs 1:6
Variable nuclear shape
Chromatin distribution
Hyperchromatism
Abnormally large nuclei
Mitoses in abnormal cells
An indication of proliferation
Seen in normal tissues with rapid turnover and in hyperplasias but weird mitosis can occur in malignant cells e.g. multipolar, trikaryokinesis
Loss of polarity means what
orientation of cells disturbed and there is disorganised growth
Well differentiated means:
closely resembles origin tissue with little or no anaplasia
Mostly benign
Moderately differentiated means:
somewhere inbetween
poorly differentiated means:
little resemblance to tissue origin
highly anaplastic appearance
undifferentiated / anaplastic
cannot be identified by morphology alone and needs molecular techniques
Grading and differentiation
Well differentiated = low/one
Moderately = intermediate/two
Poorly = high/three
Grading vs stage
Stage is a measure of prognostication / therapeutic decisions
A change in function can be called a … syndrome
Paraneoplastic syndrome
Bronchogenic carcinoma
Corticotrophin Parathyroid-like hormone Insulin Glucagon Others
Benign tumours encapsulate… what does this mean
rim of compressed fibrous tissue around the outside.
ECM (extracellular matrix) deposited by stromal cells activated by hypoxia from pressure of tumour
The tissue plane is: discrete, moveable, easily palpable and easily excised.
Pseudoencapsulation in malignant tumours
usually slow-growing but, microscopically, shows rows of cells penetrating margin
methods of metastasis
direct seeding
lymphatic spread
haematogenous spread
Direct seeding is
neoplasm penetrating a natural open field w/o physical barriers e.g. subarachnoid
most common spread of mets
lymphatic
carcinomas spread by…
lymphatics
sarcomas spread by…
haematogenous
carcinoma vs sarcoma
sarcoma is for mesodermal tissue
carcinoma is for epithelial tissue
Sentinel node definition
The first node in a regional lymphatic basin that receives lymph flow from the primary tumour
haematogenous spread features
typical of sarcomas
veins are more easily penetrated - thinner walls
bloodbourne cells follow the venous flow draining site of the neoplasm - rests in first encountered capillary bed
stroma definition
connective tissue framework that neoplastic cell are embedded in
what does stroma supply
mechanical support
intercellular signalling
nutrition
desmoplastic rxn
fibrous stroma formation due to induction of connective tissue fibroblast proliferation by growth factors from the tumour cells
Stroma contains:
cancer-associated fibroblasts
myofibroblasts
blood vessels
lymphocytic infiltrate
Cachexia
profound weight-loss despite apparent adequate nutrition
tumour-derived humoral effects that interfere with protein metabolism
Warburg effect
Produces energy by high rate of glycolysis with fermentation of lactic acid. This is what is imaged in PET scan
