neoplasm 2

Question 1

what are the affects of neoplasm on rate of growth

Answer 1

• In neoplasm rate of growth is UNCONTROLLED
• evasion of host control over growth
• limitless replicative potential
• loss of contact inhibition

Question 2

what is the clinical significance of difference in growth rate of tumors

Answer 2

• cells within the cell cycle are susceptible to chemo and radiotherapy
• -> cancers with rapid growth (high proliferative activity) are HIGHLY susceptible to chemo
• -> cancers with slow growth (inhibited activity) are RESISTANT to therapy

Question 3

how does differentiation vary in benign vs malignant tumors

Answer 3

MALIGNANT TUMORS:
- many cells within cell cycle degree of differentiation depends on proportion of cells within cell cycle
- cells/tissues formed may or may not resemble cells/tissue of origin
BENIGN TUMORS
- low proliferation activity
- cells and tissue are always differentiated

Question 4

describe the difference in normal, adenoma, and carcinoma thyroid

Answer 4

• Normal = well formed follicles; colloid
• Thyroid Adenoma = resembles normal thyroid; but forms an ENCAPSULATED THYROID MASS
• Thyroid carcinoma (well-diff.) = may resemble normal thyroid tissue; but SHOWS INVASION

Question 5

describe the difference between poorly differentiated and anaplastic carcinoma of thyroid

Answer 5

• Poorly differentiated = poor resemblance to normal thyroid; few follicles, scant colloid, has metastic potential
• ANAPLASTIC CARCINOMA = NO resemblance to normal thyroid tissue; no follicles, no colloid; HIGH METASTATIC POTENTIAL

Question 6

how do you identify poorly differentiated and anaplastic carcinoma

Answer 6

• may ONLY be indentifiable by expression of cell markers or by cytological findings

Question 7

describe Polarization in relation to anaplastic cells

Answer 7

• LOSS OF POLARIZATION
• “can’t tell UP from DOWN”
• –> full-thickness dysplasia
• -> no normal epithelial cells reamin
• -> all epithelial cells “look alike” from top to bottom

Question 8

when do you see cellular atypia

Answer 8

• seen in only PRE-MALIGNANT and MALIGNANT tumors

Question 9

how do you recognize cellular atypia

Answer 9

• CELLULAR PLEOMORPHISM
• cells vary in size and shape
• NUCLEAR CHANGES
• nuclear pleomorphism
• dense and irregular nuclear outline
• INCREASE (1:1) N/C ration (normal is 1:5)

Question 10

define pleomorphism

Answer 10

• variation in size and shape of cells and nuclei

Question 11

define hyperchomasia

Answer 11

• abundant DNA

- extremely dark staining

Question 12

define N/C ratio

Answer 12

• Nucleus to cytoplasm ratio
• -> abnormal nuclear morphology
• -> hyperchromatic (abundant DNA)
• -> increase N/C ratio in malignant tumors

Question 13

define tumor giant cells

Answer 13

• tumor giant cells represent anaplasia
• -> single huge polymorphic nucleus or > 2 nuclei
• -> nuclei are hyper-chromatic and large

Question 14

define Desmoplasia

Answer 14

• Causes changes in parenchyma/stroma ratio
• hyperplasia of activated fibroblasts
• abundant collagenous stroma
• e.g. tumors of female breast produce stony hard or scirrhous

Question 15

describe tumor angiogenesis

Answer 15

• tumor cells can proliferate rapidly and tumor can grow in size if it maintains adequate blood supply
• important factors in tumor angiogenesis
• -> VEGF
• -> FGF

Question 16

what are the Pro-angiogenic factors

Answer 16

• VEGF
• bFGF
• HIF

Question 17

what are the Anti-angiogenic factors

Answer 17

• Thrombospondin-1
• angiostatin
• endostatin
• tumstatin

Question 18

why do maligant tumors show central necrosis

Answer 18

• neoplastic transformation of a single cell results in the growth of tumor nodule (LIMITED by the ability of nutrients to diffuse into it)
• production of tumor angiogenic factors (TAF) stimulates the proliferation and ingrowth of blood vessels, enabling tumor growth to be supported by perfusion
• eventually, the tumor OUTGROWS ITS BLOOD SUPPLY, and areas of ISCHEMIC NECROSIS appear, resulting in slower growth