Exam 3 (Lecture 20) - Neoplasia 4 Flashcards
What causes neoplasia?
Carcinogens
Many carcinogens are mutagens
Many mutagens are carcinogens
(Some things are both)
Ex: Chemical, viral, physical
What contributes to carcinogenesis?
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
What are the major tenets of chemical carcinogens?
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
What is physical carcinogenesis?
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.
List 3 viruses and the types of tumors they cause.
1) Feline leukemia virus = leukemias, lymphomas
2) Hepatitis B = hepatocellular carcinomas
3) SV40 = Sarcomas
Describe the effects papillomaviruses and herpesviruses have.
Work at the DNA level.
papillomaviruses –> HPV –> cervical cancer
herpesviruses = lymphoproliferative
What do oncogenic retroviruses act on? What do they use to have their effect?
RNA; utilize reverse transcriptase
Discuss papillomaviruses.
They add new genetic material.
Tumors look like a wart/papilloma.
Species-specific strains in animals/humans.
Lesions of skin, GI, genitals, resp tracts.
Discuss retroviruses.
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)
What goes into the morphologic diagnosis of tumors?
Organ, cell of origin, benign/malignant, metastasis (?)
Ex: Oral cavity, squamous cell carcinoma, primary site
What is an example of a functional status of neoplasm?
Pituitary adenoma.
Adrenal gland hyperplasia = increased cortisol = hyperglucocorticoid
Leads to Cushing’s syndrome
*Not all endocrine tumors are functional
What are some examples of specific neoplasms in animals?
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
Who determines tumor grade?
The pathologist
What is the purpose of tumor grade?
Assists oncologists with prognostic/treatment decisions.
Give some examples of tumors and their grades.
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
Who determines tumor stage?
The clinician and/or radiologist
What is tumor stage?
Extent of tumor growth and spread
Local vs. distant spread
- Above/below diaphragm
- Local lymph nodes
- Distant lymph nodes
- Distant metastases
What are some examples of local clinical effects of neoplasia?
1) Atrophy
- loss of function
- loss of structure/strength
2) Luminal obstruction
- Mass/scirrhous response
- Necrosis > fibrous
3) Neuropathy
- Compression
- Direct disruption
4) Inflammation
What are some examples of systemic clinical effects of neoplasia, specifically bone marrow?
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)
What are paraneoplastic syndromes?
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)
What are some examples of paraneoplastic syndromes?
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)
Describe the distant spread of neoplasms. Include the 3 main pathways for metastasis.
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)
