Pathology - Disorders of Growth Flashcards
What is hyperplasia?
Increase in cell number
May be physiological or pathological
Seen in hormonally sensitive organs such as the endometrium, breast and thyroid
What effect may certain drugs have on gingival tissue?
Hyperplasia
within epithelium and underlying connective tissue
What is hypertrophy?
Increase in cell size
May be physiological or pathological
Often seen in skeletal or cardiac muscle
What is atrophy?
Reduction in cell size and number in an organ than was of normal size.
May be caused by ageing or lack of use/stimulation
What is hypoplasia?
Reduced size of an organ than never fully developed to normal size
Developmental defect
Give an example of hypoplasia
Pulmonary hypoplasia
Which disorders of growth are potentially reversible?
Hyperplasia
Hypertrophy
Atrophy
What is metaplasia?
Acquired form of altered differentiation from one mature cell type to another
Give an example of metaplasia.
Barrett’s oesophagus
What happens if environmental changes leading to metaplasia persist?
Leads to further changes that can manifest as dysplasia and progress to malignancy
How are cells classified according to their population growth pattern?
Labile
Stable
Permanent
What is characteristic of labile cells?
Continuously dividing
e.g. surface epithelia, haematopoetic cells
What is characteristic of stable cells?
Low level of replication, but may divide rapidly if stimulated
e.g. Hepatocytes, fibroblasts, endothelium
What is characteristic of permanent cells?
Non-dividing and unable to re-enter the cell cycle
e.g. neurones, skeletal and cardiac muscle
What factors inhibit apoptosis?
Growth factors
Cell matrix components
Viral proteins
What factors induce apoptosis?
Withdrawal of growth factors
Loss of matrix attachment
Viruses
Free radicals
Ionising radiation
DNA damage
Fas ligand/CD95 interaction
What is p53 protein’s role in cell life?
It induces apoptosis
How can neoplasia be classified?
Behavioural - benign or malignant
Histogenetic
What are the features of benign neoplasia?
Do not metastasise
Well differentiated, resemble normal tissue
Expansile growth with no invasion
Encapsulated
No necrosis
Normal N;C ratio
Minimal pleomorphism
Few and normal mitotic figures
Diploid
Nuclei not hyperchromatic
What is a squamous papilloma?
Usually benign papilloma affecting
skin, lip, oral cavity, tongue, pharynx, larynx
oesophagus, cervix, vagina, anal canal
What are the features of malignant neoplasms?
May metastasis
Invasive growth pattern
Not encapsulated
Variable degree of differentiation
Necrosis
Increased N:C ratio
More frequent and abnormal mitotic figures
Hyperchromatic nuclei
Aneuploid
What is a squamous carcinoma?
Cancer
skin, digestive tract, lungs
What is the name given to a benign and malignant glandular neoplasm?
Adenoma
Adenocarcinoma
How are benign and malignant squamous neoplasms named?
Squamous papilloma
Squamous carcinoma
How are benign and malignant neoplasms of fat tissues named?
Lipoma
Liposarcoma
How are benign and malignant neoplasms of endothelium named?
Angioma
Angiosarcoma
How are benign and malignant neoplasms of smooth muscle named?
Leiomyoma
Leiomyosarcoma
How are benign and malignant neoplasms of skeletal muscle named?
Rhabdomyoma
Rhabdomyosarcoma
Give examples of malignant tumours which aren’t named according to the rules
Glioma
Lymphoma
Melanoma
Seminoma
Mesothelioma
What is a teratoma?
May be benign or malignant
Encapsulated tumour with cells of more than one germ layer
Tissues of teratoma are normal in themselves, but not where they belong
e.g. teeth, hair
What is a hamartoma?
Benign tumour
Tissue elements normal for the site, but growing in a disorganised mass
Often an incidental finding
What are the key events in cancer development?
Tumour growth
Angiogenesis
Invasion and metastasis
What are the key elements of tumour growth?
Replication
Escape from senescence
Evasion of apoptosis
Limitless replicative potential
What are the components of a neoplasm?
Neoplastic cells
Blood vessels
Inflammatory cells - macrophages, lymphocytes, polymorphs
Fibroblasts
Stroma
What does the term monoclonal mean?
A group of cells all derived from the same single ancestor cell
What is dysplasia?
Premalignant process
Abnormal development but still confined to the original tissue
What is invasive growth?
Migration of cells that have detached from the primary tumour mass
What is required for invasive growth of a group of cells?
Cell-cell adhesion and communication
Inner cells are protected from immunological assault
High levels of autocrine pro-migratory factors and proteolytic enzymes
Group of cells may be heterogenous
How do single cells migrate?
Mesenchymal migration - proteolysis, traction
Amoeboid movement
What is desmoplasia?
What characteristic does it give to tumours?
Growth of fibrous or connective tissue
Gives the firm, craggy feel of cancer
Angiogenesis is required to provide oxygen and nutrition to tumour cells.
How is it modulated, and what is characteristic of the new blood vessels?
Modulated by VEGF, FGF, TNFα
Inhibited by thrombospondin-1
Vessels formed are abnormal
What is the normal route of metastasis for carcinomas?
Lymphatics
What is the normal route of metastasis for sarcomas?
Haematogenous
In what species does rous sarcoma virus cause cancer?
Chickens
not humans
Give an example of a DNA virus that causes squamous carcinoma in humans.
Human Papilloma Virus
How do DNA viruses causes malignancy?
They encode proteins that bind to and inactivate host proteins
Give examples of oncogenes.
Platelet Derived Growth Factor
Epidermal Growth Factor Receptor
ras
src
myc
Bcl2
Pim kinases
Give examples of tumour supressor genes
p53
pRB
APC
BRCA-1
NF-1
WT-1
What is the difference in inheritance between classical oncogenes and tumour supressor genes?
Oncogenes - dominant
Tumour supressors - recessive
Which genes are involved in cancer?
Oncogenes
Tumour Supressor Genes
DNA Repair Genes
Drug Metabolism
What are the features of retinoblastoma?
Mutation of a tumour supressor gene
Autosomal dominant
Variable penetrance - not everyone with mutation has the disease
Can be an isolated case
What is the two-hit hypothesis of cancer?
Two mutations are required to develop cancer.
Mutations may be inherited or acquired.
What is the role of BRAF in melanoma?
Activation of BRAF activates KRas pathway
Which gene is strongly linked to breast and ovarian cancer?
What is its role?
BRCA1
DNA strand repair
What type of protein is p53?
Tumour suppressor