Neoplasia Flashcards
What is a Neoplasm?
An abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of normal tissue, and persists in the same excessive manner after cessation of the stimuli which evoked the change.
What is the most common male and female cancer?
Male: Colon-rectum
Female: Breast
What is the difference between a cancer and a neoplasm?
Neoplasm/Tumour: Benign (usually curable/generally harmless) or malignant (cancerous) growth
Cancer: only malignant
What is the biological behaviour of a benign neoplasm?
- Slow growth rate
- No infiltration
- No metastasis
- High patient survival rates after successful surgical removal
What is the biological behaviour of a low-grade malignant/borderline neoplasm?
- variable growth rate
- locally infiltrative
- low or no metastatic potential
- intermediate patient survival rates; tendency for local recurrence after successful surgical removal
What is the biological behaviour of a malignant neoplasm?
- rapid growth rate
- infiltrative
- metastasising
- poor patient survival rates; tendency for local and distant recurrence (metastasis)
List 4 gross features of benign neoplasms
- Smooth surface with a fibrotic capsule
- Compressed surrounding tissues
- Small to large (sometimes very large)
- Unlikely to show necrosis
List 4 gross features of malignant neoplasms
- Irregular surface without encapsulation
- Destruction of surrounding tissues
- Small to large
- Can be associated with necrosis and haemorrhage
List 8 microscopic features of Benign Neoplasms
- Growth by compression of surrounding tissue
- Highly differentiated, resembles normal tissue of origin
- Cells similar to normal and resemble one another, presenting a uniform appearance
- Few mitosis, those present are normal
- Necrosis unusual; degenerative changes may be present
- Distant spread (metastasis) does not occur
- DNA content usually normal
- Karyotype usually normal
List 8 microscopic features of Malignant Neoplasms
- Growth by invasion of surrounding tissue
- Well or poorly differentiated, does not normal tissue of origin
- Enlarged hyperchromatic irregular nuclei with large nucleoli; marked variation in size and shape of cells (pleomorphism)
- Increased mitotic activity; abnormal, bizzare mitotic figures
- Necrosis and haemorrhage common
- Distant spread (metastasis) may occur
- DNA content of cells increased
- Aneuploidy, Polyploidy, Clonal genetic abnormalities
How is fibroadenoma of the breast presented macroscopically?
Palpable breast lump, freely movable benign neoplasm as it is well-encapsulated.
A result of dysregulated cell proliferation
How is advanced breast carcinoma of the breast presented macroscopically?
- Fixed, ulcerating mass
- Irregular surface (jagged edges) without encapsulation to infiltrate and destroy the surrounding tissues including the skin
- Metastasis to surrounding lymph nodes, pectoral muscle
How is fibroadenoma of the breast presented microscopically?
- Smooth fibrous capsule present (indicates an expansile non-infiltrative pattern of growth)
- Lined by a basal/myoepithelial layer
- Highly differentiated structure of ducts that resemble normal ducts
- Uniform nuclei of the cells (normal in appearance)
How is advanced breast carcinoma of the breast presented microscopically?
- Poorly formed, Haphazard appearance of malignant glands (poorly formed)
- Scattered in infiltrative manner
- Not bound by a basement membrane
- Pleomorphism (Nuclei + cell vary in shape and size)
Cytologically abnormal
- Hyperchromatic nuclei
- High nuclear-to-cytoplasmic ratio
- Irregular nuclear outline
- Coarse clumped chromatin
- Enlarged nucleoli
- Abnormal mitoses
What are the 2 principles of histologically differentiating benign and malignant tumours
- Architecture
2. Cytology
What are satellite nodules?
Metastatic nodules from Melanoma (highly malignant cancer of the skin)
What is the likely primary site of metastatic carcinoma to the liver?
GIT
What are the common organs for distant metastasis?
Liver, Lungs, Bones
Due to vascular drainage to these organs (richly vascularised)
How does one tell a metastatic tumour from a primary tumour?
The common gross appearance of metastatic tumour is multiple tumour nodules of more or less equal sizes
Are metastatic tumour nodules that look grossly “circumscribed” mean they are encapsulated?
No :(
What is the metastatic tumour in the brain called?
Solitary brain metastasis
Is the primary tumour always clinically apparent when the metastatic tumour is clinically obvious?
No :(
How can Neoplasms be classified?
- Anatomical site (Organ)
- Histogenesis (Cell of origin)
- Behaviour (Benign, Intermediate/Borderline, Malignant)
What are the different possible histogenesis classification of neoplasms
Carcinoma: Malignant epithelial neoplasms
Adenoma: BENIGN neoplasms of glandular origin arising in endocrine organ
Adenocarcinoma: Malignant neoplasms of glandular origin arising in endocrine organ
Sarcoma: Malignant mesenchymal neoplasms
Leukemia: Malignant blood cell neoplasms
Wilm’s Tumour: Malignant mixed neoplasm arising from more than one cell type (one germ layer) - renal anlage
Teratoma: BENIGN or malignant neoplasm arising from more than one cell type (multiple germ layers)
Factors determining resemblance of neoplasm to parent tissue
- Tissue architecture
- Cell morphology
- Substances produced by cells
How do we determine if it is of squamous cell origin?
Production of keratin
How to tell if it is of glandular origin?
Production of mucins (Apical Vacuoles)
What kind of neoplasm is it if there is teeth/hair found in the ovaries?
Teratoma - arises from totipotential germ cells and hence can form all tissue types (ectodermal, mesodermal, endodermal origin)
What is cancer caused by?
Cancer is the stepwise accumulation of genetic changes caused by Chemicals, Radiant energy, Viruses and other oncogenic microbes.
Some people may have cancer predisposition (genetic or immunological) which accelerates this stepwise accumulation.
What is a Carcinogen?
Any substance, radiation, or microbe that promotes carcinogenesis, which is the formation of cancer. This may be due to the ability to damage the genome, or disruption of cellular metabolic processes
What is a genetic change/mutation?
Permanent alteration in teh DNA sequence such that the sequence differs from what is found in most people.
This can occur in the gene, or gene regulatory elements leading to dysregulated expression of genes.
What are the 3 types of mutations?
- Point mutations
- Copy number variation
- Chromosomal translocation/gene rearrangement
What are the 3 types of point mutations?
- Silent mutation: Base substitutions in the triplet codon that result in no change of the amino acid/amino acid functionality when the altered messenger mRNA is translated
- Missense: Substitution of a different amino acid in the resulting protein. This may have no effect (Conservative) or may render a protein non-functional (Non-conservative)
- Nonsense: Substitution that results in the appearnace of a stop codon where previously there was a codon specifying an amino acid. This premature stop codon results in the production of a shortened and likely nonfunctional protein.
What are copy number changes?
Duplications and deletions of chromosomal segments.
This can range from small deletions/insertions (1-50bp) to huge chromosomal aberrations.
What are chromosomal translocations?
Chromosomal breakage and reattachment resulting in abnormal rearrangements of chromosomes.
Eg. Burkitt’s Lymphoma (Excessive and dysregulated synthesis of Myc protein)
What is an activating mutation?
Mutation which causes the gene to become functionally activated independent of normal control mechanisms.
What is an inactivating mutation?
Mutation which results in the loss of the normal function of the gene.
What are some features of acquired gene mutations?
- Most common cause of cancer
- Occurs in non-gamete cell after the conception of the individual
- Passed along only to daughter cells descended from that cell, and so are not present in all cells of the body
What are some features of germline gene mutations?
- Rare
- Occurs in a reproductive cell (sperm or egg)
- Mutation incorporated into the DNA of every cell in the body
- Heritable and can cause cancer family syndromes