Exam 3 (Lecture 20) - Neoplasia 4

Question 1

What causes neoplasia?

Answer 1

Carcinogens

Many carcinogens are mutagens

Many mutagens are carcinogens

(Some things are both)

Ex: Chemical, viral, physical

Question 2

What contributes to carcinogenesis?

Answer 2

1) Genetic and other risk factors
- Ex: hormone status for canine
mammary tumors
- Dogs and Mammary Tumors:
- If spayed prior to 1st heat
= decreased risk
- If spayed after 1st heat = increased
risk

2) Germ line mutations
- Genetic predisposition/heredity
- Ex: mutation in tumor suppressor gene
- Casuses retinoblastoma in very
young children

Question 3

What are the major tenets of chemical carcinogens?

Answer 3

1) Dose dependent (additive effect)

2) Latency (make its harder to trace the cause)

3) Progeny cells acquire traits (mutation w/o DNA repair = just make more cells)

4) Co-carcinogens are important in increasing cell replication

5) Proliferation is required (they anchor the mutation in that cell line)

6) Malignancy requires multiple steps

Question 4

What is physical carcinogenesis?

Answer 4

Substance acts by inducing mutations.

Radiation is the biggest physical carcinogen.

Complete carcinogen = can initiate AND promote tumorigenesis.

Ironically, also used in diagnostic and treatment modalities.

Question 5

List 3 viruses and the types of tumors they cause.

Answer 5

1) Feline leukemia virus = leukemias, lymphomas

2) Hepatitis B = hepatocellular carcinomas

3) SV40 = Sarcomas

Question 6

Describe the effects papillomaviruses and herpesviruses have.

Answer 6

Work at the DNA level.

papillomaviruses –> HPV –> cervical cancer

herpesviruses = lymphoproliferative

Question 7

What do oncogenic retroviruses act on? What do they use to have their effect?

Answer 7

RNA; utilize reverse transcriptase

Question 8

Discuss papillomaviruses.

Answer 8

They add new genetic material.

Tumors look like a wart/papilloma.

Species-specific strains in animals/humans.

Lesions of skin, GI, genitals, resp tracts.

Question 9

Discuss retroviruses.

Answer 9

Cattle = bovine leukosis virus = lymphoma

Cats = feline leukemia virus = leukemia
- Neoplastic lymphocytes in circulation
and /or in bone marrow
- Solid
- lymphosarcoma in vet med (lymphoma
in human med)

Question 10

What goes into the morphologic diagnosis of tumors?

Answer 10

Organ, cell of origin, benign/malignant, metastasis (?)

Ex: Oral cavity, squamous cell carcinoma, primary site

Question 11

What is an example of a functional status of neoplasm?

Answer 11

Pituitary adenoma.

Adrenal gland hyperplasia = increased cortisol = hyperglucocorticoid

Leads to Cushing’s syndrome

*Not all endocrine tumors are functional

Question 12

What are some examples of specific neoplasms in animals?

Answer 12

1) Bracken fern: cattle
- Bovine enzootic hematuria
- Bladder tumors
- plant compound: ptaquiloside
- Suspected interaction with bovine
papillomavirus (BPV-2)

2) White faced horses/cattle/cats: squamous cell carcinoma

3) Lymphoma in animals vs. humans

Question 13

Who determines tumor grade?

Answer 13

The pathologist

Question 14

What is the purpose of tumor grade?

Answer 14

Assists oncologists with prognostic/treatment decisions.

Question 15

Give some examples of tumors and their grades.

Answer 15

1) Mast cell tumors
- Low grade/high grade
- MI, multinucleated cells, cell uniformity

2) Soft tissue sarcomas
- Includes fibrosarcomas, liposarcomas
- Grades I/II/III
- MI, presence of necrosis,
differentiation

3) Mammary tumors
- % tubule formation, nuclear
uniformity, MI
- Grades I/II/III

Question 16

Who determines tumor stage?

Answer 16

The clinician and/or radiologist

Question 17

What is tumor stage?

Answer 17

Extent of tumor growth and spread

Local vs. distant spread
- Above/below diaphragm
- Local lymph nodes
- Distant lymph nodes
- Distant metastases

Question 18

What are some examples of local clinical effects of neoplasia?

Answer 18

1) Atrophy
- loss of function
- loss of structure/strength

2) Luminal obstruction
- Mass/scirrhous response
- Necrosis > fibrous

3) Neuropathy
- Compression
- Direct disruption

4) Inflammation

Question 19

What are some examples of systemic clinical effects of neoplasia, specifically bone marrow?

Answer 19

1) Anemia
- anemia of chronic disease

2) Bone marrow damage
- myelophthisis
- effacement of marrow by neoplastic
cells or inflammation/organisms
- myelofibrosis
- replacement of marrow by fibrous
tissue
- outcome
- thrombocytopenia (increased risk
for hemorrhage)
- neutropenia (increased risk for
infection)

Question 20

What are paraneoplastic syndromes?

Answer 20

Symptoms or signs in neoplastic disease that are unexplained by the physical effects of local or distant spread.

Ex: Cachexia, anorexia, malaise, or fever (and/or fever of unknown origin)

Question 21

What are some examples of paraneoplastic syndromes?

Answer 21

1) Lymphoma (dogs)
- hypercalcemia of malignancy
- PTH-related protein

2) Anal sac gland adenocarcinoma

3) Sertoli cell tumor (dogs)
- hyperestrogenism
- feminization of male dogs
- ectopic hormone production

4) Humans: pancreatic carcinoma and panniculitis (sometimes the first sign is unexplained itchiness)

Question 22

Describe the distant spread of neoplasms. Include the 3 main pathways for metastasis.

Answer 22

Primary site = cell of origin
Secondary site(s) = metastatic site

3 Main Pathways for Metastasis:
- Hematogenous
- Lymphatic
- Implantation or transcoelomic

*Major cause of death: organ failure (lung, liver, brain)