Neoplasia (Malignancy, Effects & Spread) Flashcards
Why does a mesothelioma arising in, for example, the pericardial cavity spread only within that cavity?
When mesothelioma arises on a serosal surface (i.e., pericardium, peritoneum or pleura) it easily spreads transcoelomically within the cavity, but cannot cross the anatomic barriers of the fibrous pericardium or the diaphragm.
A poorly differentiated neoplasm has a better prognosis than a well-differentiated neoplasm. True or false?
FALSE
Malignant neoplasms are typically poorly demarcated. True or false?
TRUE
What is the meaning of the term paraneoplastic effect?
Paraneoplastic effects are indirect and remote effects that are caused by tumor cell products rather than by the primary tumor or its metastases
Compare the cellular differentiation of a benign fatty tumor (lipoma) with that of a malignant fatty tumor (liposarcoma)
The benign lipoma is composed of mature fat cells indistinguishable from normal cells. The liposarcoma consists of poorly differentiated cells, many of which do not have the morphologic features characteristic of adipocytes.
Compare the number and appearance of mitotic figures in a “typical” benign and “typical” malignant neoplasm
Benign: mitotic figures are relatively scarce and of normal appearance; Malignant: mitotic figures are relatively numerous and may have a bizarre appearance
Who grades neoplasms and why?
Grading is carried out by veterinary pathologists. The assumption is that grading provides some predictive ability about future behavior of the tumor. This is not universally true, however, and tumor staging (by a veterinary oncologist) is often more useful.
Explain the key differences in the extent and type of local invasion by a “typical” benign and “typical” malignant neoplasm
Benign: expands and compresses, but does not invade or infiltrate adjacent normal tissue; Malignant: infiltrates and invades adjacent normal tissue
Leukemia may be classified as either ___(a)____ or ___(b)___ based on the degree of differentiation of the neoplastic cells and their biologic behavior. What are terms (a) and (b)?
(a) Acute; (b) Chronic
Name three common paraneoplastic effects seen in veterinary medicine.
- Cachexia
- Hypercalcemia of malignancy
- Hypertrophic osteopathy
A well-differentiated neoplasm has a better prognosis than a poorly differentiated neoplasm. True or false?
TRUE
Mesothelioma is a malignant neoplasm of mesothelial cells. Mesothelial cells, along with endothelial and synovial cells, are derived from which layer of the trilaminar embryonic disc?
Mesoderm. See your Neoplasia 1 lecture for an explanation.
You excise a subcutaneous neoplasm from a dog and submit it to a veterinary pathologist. The pathologist may be able to [choose one]: (a) grade the neoplasm; (b) stage the neoplasm.
(a) Grade
What are the four most important characteristics of a neoplasm that help determine if it is benign or malignant?
- Presence or absence of metastasis
- Growth rate and number & appearance of mitotic figures
- Degree of local invasion, and whether it is expansile or infiltrative
- Degree of differentiation of neoplastic cells
You radiograph a dog and notice severe symmetrical periosteal proliferation in all distal long bones. What is the name of this disease?
Hypertrophic osteopathy. This is a paraneoplastic effect of space-occupying thoracic masses that results in periosteal proliferation in the distal long bones. The mechanism is unknown.
Who stages neoplasms and why?
Staging is carried out by veterinary oncologists. It gives an indication of the extent of tumor growth and spread, which guides the clinician in developing a therapeutic plan and offering an estimate of prognosis to the client.