class notes 12 - flashcards

Flashcards generated from lecture notes on disorders of cell growth and neoplasia.

What is a hamartoma?

An abnormally organized mass of well-differentiated tissue in its normal location.

How does the growth of a hamartoma relate to the animal's growth?

It parallels the animal's growth.

Give an example of a hamartoma.

A small irregular mass of bronchial cartilage and epithelium in the lung.

What is a choristoma?

A small amount of normal tissue in an abnormal location.

What is another name for choristomas?

Rests or embryonal rests.

Provide an example of a choristoma.

Adrenal cells under the renal capsule.

What is ectopia cordis?

A heart that develops outside of the thoracic cavity.

Define hypoplasia.

Underdevelopment of an organ with fewer than the normal number of cells.

Does hypoplasia always originate in the embryo?

No, it can occur later, such as gonadal hypoplasia due to pituitary deficiency.

What are the two categories of hyperplasia?

Physiological and pathological.

Why can it be hard to tell nodular hyperplasia and benign neoplasm apart?

The histologic distinction can be difficult or arbitrary.

What risk is associated with prolonged pathologic hyperplasia?

Neoplastic transformation.

Name 4 reversible disorders of cell growth

Hyperplasia, Hypertrophy, Atrophy, Metaplasia

What are the two connotations of dysplasia?

Abnormal tissue organization or changes in epithelium.

What epithelial changes can occur in dysplasia?

Abnormal cell morphology and changes in architectural orientation.

Can dysplasia be reversible?

Yes, it may resolve, or it may progress to neoplasia.

Give an example of dysplasia.

Cervical dysplasia in women associated with HPV.

What is 'collie nose'?

Solar keratosis in dogs with lightly pigmented nasal planum.

How does sunlight exposure protect against UV damage?

It stimulates vitamin D production and melanin production.

What effect does vitamin D have on keratinocyte precursors?

It causes the arrest or delay of replication of keratinocyte precursors allowing time for DNA repair.

What are two irreversible disorders of cell growth?

Necrosis and neoplasia.

Is neoplastic transformation reversible?

No, even if the inciting stimuli are removed.

How is the growth of neoplastic tissue regulated?

It is autonomous from regulation by the body or surrounding tissues.

How does the growth of neoplastic tissue compare to normal tissue?

It exceeds the normal tissue from which it was derived.

What is the meaning of the word 'tumor'?

Swelling.

What is another word for tumor?

Neoplasm.

What is another word for a malignant neoplasm?

Cancer.

Are benign tumors invasive?

No, they stay in one place.

How common is cancer in older dogs?

Cancer (and associated euthanasia) is the most common cause of demise of old dogs.

Is cancer common in farm animals?

No, because of life-span limitations, with some economically important exceptions.

Name one reason why benign vs malignant classification is used.

Intended to predict the behaviour of a neoplasm.

What are the features of a benign tumor?

Do not invade, do not recur, do not metastasize, grow slowly, do not cause cachexia.

Do bengin tumors invade?

No, they are expansile instead of invasive

What are the features of a malignant tumor?

Are invasive, often recur, may metastasize, often grow quickly, may cause cachexia.

What are the gross features of benign neoplasms?

Solitary mass, well-demarcated, may be encapsulated, usually easily moveable, uniform consistency.

What are the gross features of malignant neoplasms?

May be solitary or multiple, indistinct demarcation, usually not encapsulated, may be immobile, variable consistency, may have finger-like projections, may have metastasized.

Benign neoplasms are __ differentiated.

Well

Malignant neoplasms are __ differentiated.

Poorly

Which type of neoplasm has a uniform cell size and shape?

Benign

Which type of neoplasm is well-demarcated from adjacent tissue?

Benign

Which type of neoplasm is encapsulated?

Benign

Which type of neoplasm is invasive?

Malignant

Which type of neoplasm has many mitotic figures?

Malignant

Which type of neoplasm has uniform nuclei?

Benign

Which type of neoplasm has invasion of lymphatics and veins?

Malignant

Which type of neoplasm has areas of necrosis and haemorrhage?

Malignant

Which type of neoplasm has desmoplasia?

Malignant

Give an example of an epithelial benign tumor

Papilloma(wart)

Give an example of an epithelial malignant tumor

Squamous cell carcinoma

Give an example of a mesenchymal benign tumor

Fibroma

Give an example of a mesenchymal malignant tumor

Fibrosarcoma

What suffix do benign epithelial tumors have?

Oma

What suffix do malignant epithelial tumors have?

Carcinoma

What suffix do benign mesenchymal tumors have?

Oma

What suffix do malignant mesenchymal tumors have?

Sarcoma

What is required for cancer to develop?

Mutation of DNA.

What behavioral alterations must occur for cancer to develop?

Independent proliferation, avoidance of apoptosis, development of immortality, development of metastatic capability.

Define Carcinogen

A substance that induces the formation of cancer.

What are the steps in the carcinogenesis model presented?

Initiation, Promotion, Progression

Describe Initiation

The first step to induce a cancer-susceptible state, resulting from DNA mutations.

What changes are caused by an initiation event?

Increased frequency of mitosis, inhibition of apoptosis, decreased ability to repair damaged DNA, increased lifespan of cell line.

Is initiation an inheritable change?

Yes, it is passed to daughter cells.

Why can't terminally differentiated cells become neoplastic?

Because they cannot divide and copy over the mutated DNA.

Describe Promotion

Stimulation of initiated cells to undergo mitosis.

Does a promoter damage DNA by itself?

No, but promotion incites cells to divide.

What is the effect if a promoter is applied before the initiating agent?

Promoters have no effect.

Name some factors involved in promotion.

Hormones, inflammation, wound healing, epigenetic mechanisms.

Describe Progression

Serial mutational events that confer ever-increasing transformation of an altered cell line.

What are some factors contributing to neoplastic progression?

Increased mitosis, inhibition of apoptosis, depressed tumour suppressor proteins, removal of restrictions on cell growth, expression of inactive genes, aneuploidy, tumour heterogeneity.

How might increased copies of proto-oncogenes lead to increased mitosis?

By having altered proto-oncogenes (oncogenes) that are always "on"

Name reasons why tumour suppressor proteins may result in depressed function

Translocation of promoter sequences, deletion of tumour suppressor genes, or mutation of the tumour suppressor gene.

What is aneuploidy?

An altered karyotype with lost, extra, or altered chromosomes.

Define Metastasis

The transplantation and growth of neoplastic cells in distant sites from the original mass.

What is the role of intercellular adhesion molecules in metastasis?

Loss of these molecules allows epithelial cells to be released from adjoining mates.

How do normal cells usually respond if not attached to an extracellular matrix?

They will undergo apoptosis (anchorage dependence).

How many basement membranes must a cell breach to exit a blood vessel?

One basement membrane of the endothelium.

What are integrins and what is their role in metastasis?

Extracellular matrix adhesion molecules that attach to the RGD peptide in fibronectin, dictating specific sites of metastasis.

What are transmissible neoplasms?

Neoplasms that can be transplanted from one individual to another.

How is transmissible venereal tumour of dogs (TVT) spread?

By intimate physical contact.

is transmissible venereal tumor usually fatal?

no, most cases will resolve spontaneously

How is Devil facial tumour transmitted?

By biting.

What is the outcome of devil facial tumor?

Lethal, as the tumors are invasive and expansile.

Name some examples of retroviruses

MMTV, FeLV, BLV, HTLV, HIV, FIV, SIV, BIV

How do viruses cause cancer?

By insertional mutagenesis

What is exciting about Marek's disease?

It is the first cancer successfully controlled by vaccination.

What is the zoonotic relevance of MMTV?

Evidence strongly implicates mice and MMTV with a significant percentage of malignant breast cancers in women.

Chemical carcinogens often require what to become active?

Bioactivation, usually in the liver by the cytochrome P-450 oxygenase system.

How does aromatics and azo dyes cause cancer?

Damaging DNA

Name a kind of polycyclic aromatic?

Products in tobacco smoke

Name some alkylating compounds

Many cancer chemotherapeutic drugs

Where are nitrosamines and amides produced?

In the gastrointestinal tract from nitrate preservatives.

Name a naturally occuring compound that act as carcinogens

Aflatoxins produced in mouldy foods

How does radiation cause cancer?

Causes DNA breaks, cross-links, formation of pyrimidine dimers.

Which type of UV light generates free radicals?

UV-A

Which type of UV light causes crosslinking between cytosine and thymine to form pyrimidine dimers?

UV-B

What cancers are linked to excessive sunlight exposure in animals and humans?

Skin cancers, including cancer eye in cattle, discoid lupus in collies, and various cancers in humans.

What cancers are linked to ionizing irradiation?

Leukaemias and thyroid carcinomas.