Neoplasia Flashcards
1
Q
Neoplasia
A
New growth
- an abnormal mass of tissue, with excessive and uncoordinated growth that persists after the original stimulus is absent
2
Q
Genetic and metabolic cellular changes
A
Cells fail to respond to normal control
3
Q
Proliferation
A
Microscopic or gross tumor
4
Q
Tumor
A
Originally used to describe inflammation, now applies to neoplasia
5
Q
Benign
A
Does not invade local tissues, still may cause disease
6
Q
Malignant
A
Invade, spread within the body (metastasis), resulting in death
7
Q
Preneoplastic change
A
Stepwise progression
- change in morphology that indicates abnormal cellular content, and thus an increased chance for neoplasia
8
Q
Dysplasia
A
Disorderly pattern of growth
- not lined up well, different sizes, etc
9
Q
Anaplasia
A
Loss of differentiation
- neoplastic morphology par excellence
10
Q
Tumor types
A
Usually 1 cell of origin
- mesenchymal or epithelial
11
Q
Mesenchymal suffixes
A
- oma: benign
- sarcoma: malignant
12
Q
Epithelial tumors arise from ______, _____, and ______
A
Endoderm, mesoderm, and ectoderm
13
Q
Adenoma
A
Benign, from a gland, or making a tubular pattern
14
Q
Papilloma
A
Benign, exophytic/frondose, from a skin or mucosal surface
15
Q
Polyp
A
Benign, smooth, bulging, mucosal surface
16
Q
Malignant of epithelial origin
A
Carcinoma
- nests, cords, islands of cells
17
Q
Adenocarcinoma has a ______
A
Glandular pattern
18
Q
Carcinoma in situ
A
Preinvasive form, neoplasm remains within the epithelium without invasion
19
Q
For an epithelial cell to be malignant, what has to occur?
A
The tumor must have broken through the basement membrane
20
Q
Squamous
A
Tumor that demonstrates stratified squamous epithelium
21
Q
Mucinous
A
Tumors that produce abundant mucin
22
Q
Desmoplasia
A
Formation of abundant collagen stroma (scirrhous response)
23
Q
Anaplastic tumors
A
Undifferentiated!
- no morphological clue to cell of origin
- resembles fetal tissue
24
Q
Mixed tumors
A
Multiple cell types
25
Stem cell origin
Differentiates into various mature cell types
26
Teratomas
Occur in areas that have reproductive tissues
- tumor started from completely undifferentiated cells (germ cells)
- contains bone, CT, epithelial tissue, nervous tissue
27
What tumor type makes up 50% of mammary tumors in dogs?
Benign mixed mammary tumor in dogs
28
What are 2 tumor like lesions?
- hamartoma
| - choristoma
29
Hamartoma
Disorganized mature cells in a normal location
| - red spots on skin that are dilated, blood filled resembling hemangiomas
30
Choristoma
Normal mature tissue in an abnormal site
| - dermoid: patch of hair that grows out of cornea
31
Tumor characteristics
Can arise from any normal tissue!
- loss of differentiation
- unlimited proliferative potential due to continuous cell division and resistance to cell death
32
____ and ____ establish prognosis and determine treatment
Tumor grade (degree of differentiation) and stage (extent of spread)
33
Differentiation
- benign: well differentiated, structure similar to tissue of origin, no anaplasia
- malignant: poorly differentiated, tissue of origin may be unclear, variable anaplasia
34
Growth rate
- benign: slow and progressive, rare mitoses, normal mitoses, little necrosis
- malignant: rapid growth, frequent mitoses, abnormal mitoses, necrosis
35
Local invasion
- benign: no invasion, cohesive growth, capsule present
| - malignant: local invasion, infiltration, lacks capsule
36
Metastasis
- benign: no metastasis
| - malignant: sometimes present
37
Neoplastic cells lose ______
Mature differentiated features of cell morphology and organization
38
Malignancies are ____ differentiated than benign
Less!
39
Neoplastic changes reflect ______
- high mitotic rate
- chromosomal abnormalities
- high metabolic activity
40
Anisocytosis
Variation in cell size
41
Anisokaryosis
Variation in nuclear size
42
Pleomorphism
Variation in cell shape
43
Hyperchromasia
Dark nuclei due to increased DNA content
44
Neoplastic cells have _____ cytoplasm
Basophilic due to many ribosomes
- loss of cilia and pigment
- loss of normal architecture correlates with increased cell independence from surrounding tissues
45
_____ is used to identify characteristic features of cells
Immunohistochemistry
46
________ occurs in many cases
Loss of specialized functions
| - exception: thyroid carcinomas, plasma cell tumors
47
What 2 structures are used to distinguish between epithelial and mesenchymal?
- cytokeratin found in epithelial cytoskeleton
| - mylentin found in mesnechymal cells
48
Proliferation
Neoplastic cells escape normal limits on cell division
- independent from stimulatory/inhibitory factors
- apoptotic signals
- tumor growth is not exponential! --> irreversible cell cycle arrest and cell death occur within tumors
49
Cell division
Stimuli/inhibitors from local environment
- quiescent cells in G0
- DNA damage --> cycle arrests at checkpoints (G1/S, G2/M)
50
____ arrests cell cycle to allow DNA repair
p53
- tumor suppressor
- neoplastic cells do not respond to p53 or other signals = accumulate more mutations
51
Mitotic index
Average number of tumor cells in a 400x field that have condensed chromosomes and lack a nuclear membrane
- used as guide to assess malignancy
52
Senescence
Damaged cells permanently arrest in G1, a result of p53 or retinoblastoma pathways
- neoplastic cells maintain telomerase --> prevents senescence
53
Apoptosis
Programmed cell death
| - neoplastic cells inactivate p53, removing a pro-apoptotic pathway
54
Latent period
Time before a tumor is clinically detectable
- 1 cm diameter, 30 rounds of division from a single cell
- may be developing for years
55
How many divisions are required to progress from a 1 gram tumor to a 1 kg tumor?
10 divisions
| - rapid progression!
56
Transformation are altered by
- cell death rate
- mitotic rate
- blood supply
- immune response
57
Tumor development is exemplified by
- initiation
- promotion
- progression
58
Initiation
Introduction of an irreversible genetic change by a carcinogen (stable mutation)
- may allow a selective advantage in the cell
59
Promotion
Stimuli (promoters) cause the growth of the initiated cells
- benign tumor
- promoters are non-mutagenic
60
Progression
Benign tumors become malignant
- complex process of genetic and epigenetic changes in the tumor cells
- genetic instability and tumor heterogeneity
61
Tumors are believed to derive from _____
A single cell (clonal)
- each new mutation leads to a subclone of tumor cells
- subclones are selected for increased malignancy (high proliferative rate, evasion of immune response, angiogenesis), clonal selection
62
Stroma
```
Connective tissues (collagen, proteins, glycoprotein, vessels, fibroblasts, immune cells)
- amount of stroma varies in tumors
```
63
Stroma of epithelial tumors is often derived from _______
Normal mesenchymal cells
64
Stroma of mesenchymal tumors is produced by the _____
Neoplasm
| - osteosarcomas produce bone
65
Stroma may form a _____ around the tumor to limit spread
Capsule
66
Stromal interactions
- complex: exchange of many factors that modulate growth
| - extensive fibrosis reaction (desmoplasia) is referred to as a scirrhous response
67
Without new vessels, tumor size is limited to_____
2mm
68
Angiogenesis
Vessel development
- recruitment of endothelial cells, migration, maturation
- vessels are tortuous, irregular, unstable, leaky
- structure and function in tumors is abnormal
69
_____ and _____ can recognize tumor antigens and destroy neoplastic cells
Innate system (NK cells, macrophages) and the adaptive system (lymphocytes)
70
Metastasis
Defining characteristic of malignancy, cells develop ability to spread to distant sites, forming additional masses
- cause of cancer related to mortality
- via lymphatics, blood vessels, direct dissemination
- inefficent
71
What must occur for metastasis to happen?
- BM penetration via proteases
- intravasation: penetration of epithelium and access vessel lumen
- embolisation: attack by leukocytes = tumor cell death
- platelet attachment: protective of cancer cells
- extravasation into tissues
72
Mesenchymal cells prefer to travel in the _____
Blood
| - if in GIT --> portal vein --> liver
73
Epithelial cells prefer to travel in the _____
Lymphatics
| - goes to venous blood --> heart --> lungs (#1 place for metastasis)
74
The site of metastasis is determined by ______
Cells ability to interact with endothelial cells and ECM
- suitable site for growth
- many tumors have preferred sites for metastasis
75
Lymphatic spread
Carcinomas, especially thru lymph nodes
- those closest to tumor are affected first
- not a stepwise process! nodes can be bypassed
- mets to local lymph node indicate systemic spread
76
Hematogenous spread
Sarcomas, especially veins (thinner walls)
- reach vena cava, heart = mets to the lungs
- portal vein invasion = mets to the liver
- ex: malignant pheochromocytomas commonly invade vena cava
77
Transcoelomic spread
Cancers that arise from visceral tissue surfaces
- few barriers to spread
- mesothelioma
- carcinomatosis
- ex: canine ovarian, pancreatic, and lung carcinomas
