Histopathology of Cancer – Basic Concepts and Terminology Flashcards
(28 cards)
What is Neoplasia?
= new growth
- new growth
• Monoclonal proliferation of cells to form a tumour/ mass
List 3 characteristics of neoplasms
1) Growth exceeds stimulus and becomes autonomous
2) Neoplasms may be benign or malignant
3) Neoplasms resemble the cell of origin!
What is cancer?
malignant neoplasm
What is Hyperplasia?
increase in cell number, proportionate to stimulus
What is Hypertrophy?
increase in cell size, proportionate to stimulus
What is a Choristoma?
tumour composed of normal cells/ tissues present in an abnormal place
What is a hamartoma?
tumour composed of disorganised growth of different cell types normally present in that organ
What is a teratoma?
tumour composed of derivatives of all 3 embryological layers (ectoderm, endoderm & mesoderm) e.g. in ovary
What is dysplasia?
‘abnormal growth’; may form a benign neoplasm (e.g. adenoma); often a precursor of malignant neoplasms
How do benign and malignant neoplasms differ in biological potential (behaviour)?
MALIGNANT neoplasms have the potential to spread (metastasise);
BENIGN neoplasms do not
• Borderline (uncertain malignant potential) tumours are intermediate
• Benign neoplasms uncommonly transform into malignant neoplasms – has intermed chance of becoming worse
Which malignant tumors arise from these cells of origin?
- Epithelium
- Mesenchyme
- Primitive lymphoid/ myeloid cells (blasts)
- Mature lymphocytes
- Plasma cells
- Mesothelium
- Melanocytes
- Germ cells
- carcinoma
- sarcoma (from cartilage)
- leukaemia
- lymphoma
- myeloma
- mesothelioma
- melanoma
- teratoma, seminoma, choriocarcinoma, etc
Which benign tumors arise from these cells of origin?
- Squamous epithelium
- Glandular epithelium
- Transitional epithelium
- Fat
- Vessels
- Nerves
- Bone
- Cartilage
- Smooth muscle
- Skeletal muscle
- squamous papilloma
- adenoma
- transitional cell papilloma (malignant would be carcinoma)
- lipoma
- lymph/haemangioma
- neuroma
- osteoma
- chondroma
- leiomyoma
- rhabdomyoma
5 Differences between benign and malignant neoplasms
- Clinical presentation (history, examination)
- Macroscopic appearance
- Microscopic appearance (histology)
- Behaviour and prognosis
- Management
Microscopic differences between benign and malignant neoplasms
B: Close resemblance to cell of origin M: Poor resemblance B: Uniform growth pattern M: Irreg/haphazard growth pattern B: Normal nuclear size, normal cytoplasmic ratio M: Enlarged, irreg B: Smooth nuclear mem M: Irreg nuclear mem B: Normal tumor cells in mitosis M: Inc tumor cells in mitosis B: Tumor stroma - no necrosis/haemorrhage M: Coagulative necrosis & haemorrhage
List the principles of carcinogen
1) Initiation
2) 4 classes of normal genes are damaged in carcinogenesis
3) Clonal expansion
4) Driver mutations and epigenetic aberrations
5) Darwinian selection
Describe the process of initiation of carcinogen
- non-lethal genetic damage to the cell:
1) Inherited germline mutation
2) Env damage
3) Random
What are the diff forms of genetic damage to the cell?
point mutation, translocation, deletion, gene amplifications, polysomy
List 4 classes of normal genes are damaged in carcinogenesis
1) proto-oncogenes – growth promoting – mutation in proto-oncogene can prod oncogene
2) tumour suppressor genes (anti-oncogenes) – growth inhibiting e.g. p53, BRCA
3) genes that regulate apoptosis (programmed cell death)
4) genes involved in DNA repair
Describe driver mutations and epigen aberrations (step 4)
Driver mutations: loss-of-function mutations in genes that maintain genomic integrity
Epigen mod: DNA methylation →↓ expression of that gene - modifications of histones (proteins which package DNA into chromatin)→↓ or ↑gene expression
Step-wise accumulation of complementary mutations and epigen mod are required for carcinogen
Describe clonal expansion (step 3)
A single pre-cursor cell which has acquired non-lethal damage it its DNA undergoes clonal expansion to form a neoplasm
Describe Darwinian selection
- The tumour sub-clones which have acquired the genetic abnormalities which make them the ‘fittest’ cancer cell will out-grow the others
- Some tumour sub-clones can acquire mutations which make them more likely to survive chemotherapy and radiotherapy
Describe mech of spread of cancer cells
- Local invasion (contiguous spread)
- Iatrogenic implantation
- Metastatic spread
List the diff ways of metastatic spread
- via lymphatics
- via bloodstream (haematogenous)
- extravascular migratory metastasis (EMM) – tumor finds blood vessel + forms a new mass
- perineurally
- trans-peritoneally i.e. tumor cells can travel through ascites
- aerogenous (through lungs)
- by fluid (eg urine)
List types of cytology samples for cancer
- naturally exfoliated, eg urine, sputum
* artificially exfoliated, eg washings, brushings, scrapings
