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Flashcards in CH3 - Principles of Neoplasia Deck (169)
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121

Angiogenesis and tumors

(production of new blood vessels) is necessary for tumor survival and growth.

122

FGF and VEGF

(angiogenic factors) are commonly produced by tumor cells.

123

Tumor survival and the immune system?

Avoiding immune surveillance is necessary for tumor survival

124

Immune surveillance and tumor survival?

Mutations often result in production of abnormal proteins, which are expressed on MHC class 1, CD8+ T cells detect and destroy such mutated cells, Tumor cells can evade immune surveillance by downregulating expression of MHC class 1.

125

How do tumor cells evade immune surveillance?

by downregulating MHC class 1

126

Immunodeficiency and cancer

(both primary and secondary) increases risk for cancer

127

Accumulation of mutations eventually result in what?

tumor invasion and spread

128

Epithelial tumor cells are normally attached to one another by what?

cellular adhesion molecules (e.g., E-cadherin).

129

Downregulalion of E-cadherin leads to what?

dissociation of attached cells

130

How do the tumor cells spread locally?

Cells attach to laminin and destroy basement membrane (collagen type IV) via collagenase. Cells attach to fibronectin in the extracellular matrix and spread locally

131

Metastasis of tumor cells.

Entrance into vascular or lymphatic spaces allows for metastasis (distant spread)

132

What are the routes of metastasis?

Lymphatic, hematogenous, seeding of body cavities

133

Lymphatic spread is characteristic of what?

carcinomas

134

Where does the initial lymphatic spread occur?

In the regional draining lymph nodes

135

Hematogenous spread is characteristic of what?

sarcomas and some carcinomas

136

What are some examples of hematogenous spread?

renal cell carcinoma, hepatocellular carcinoma, follicular carcimoma of the thyroid, choriocarcinoma

137

Seeding of body cavities is characteristic of?

ovarian carcinoma, often involves the peritoneum 'omental caking'

138

What is omental caking?

where the peritoneum is often involved in ovarian carcinoma

139

Describe benign tumors.

tend to be slow growing, well circumscribed, distinct, and mobile

140

Malignant tumors are usually

rapid growing, poorly circumscribed, infiltrative, and fixed to surrounding tissues and local structures.

141

What is generally required before a tumor can be classified as benign or malignant with certainty?

Biopsy or excision

142

Why is biopsy necessary?

Some benign tumors can grow in a malignant-like fashion, and some malignant tumors can grow in a benign-like fashion.

143

Benign tumors are usually

well differentiated

144

What are some characteristics of benign tumors?

1. Organized growth 2. Uniform nuclei 3. Low nuclear to cytoplasmic ratio 4. Minimal mitotic activity 5. Lack of invasion (of basement membrane or local tissue) 6. No metastatic potential

145

Malignant tumors are classically

poorly differentiated (anaplastic)

146

Characteristics of malignant tumors include

1. Disorganized growth (loss of polarity) 2. Nuclear pleomorphism and hyperchromasia 3. High nuclear to cytoplasmic ratio 4. High mitotic activity with atypical mitosis 5. Invasion (through basement membrane or into local tissue)

147

What is the hallmark of malignancy?

Metastatic potential - benign tumors never metastasize

148

What is the target cell type for the immunohistochemical stain of Keratin?

Epithelium

149

What is the target cell type for the immunohistochemical stain of Vimentin

Mesenchyme

150

What is the target cell type for the immunohistochemical stain of desmin

Muscle