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What are the clinical classification of tumors?
- behavior of tumor
- clinical presentation and outcome
What are the histological classification of tumors?
microscopic cell type
What is benign?
- Limited growth potential
- usually good outcome for patient
What is malignant?
- Uncontrollable growth
- eventually kills the patient
What are the different ways to compare benign and malignant tumors?
- Gross feature
- microscopic features
- cellular features
- biologic features
What do benign tumors look like?
sharply demarcated from surrounding tissue - clean sharp edges, well circumscribed, often encapsulated
Do benign tumors grow fast or slow?
What is the external surface of a benign tumor look like?
Is necrosis and hemorrhage present in benign tumors?
What is the capsule like of a benign tumor?
connective tissue or adjacent normal tissue - which is compressed, atrophied, and fibrotic
Are malignant tumors well circumscribed?
No, not clearly separated from normal tissue
What is the growth pattern like of a malignant tumor?
- invades surrounding tissue
- like plant roots grow in soil
Is the growth rate of a malignant tumor fast or slow?
Do malignant tumors have capsules?
What is the external surface of malignant tumors like?
Is necrosis and hemorrhaging present in malignant tumors?
What does a benign tumor look like microscopically?
Composed of cells that resemble the tissue of origin
What does a malignant tumor look like microscopically?
- Composed of cells that can look different from tissue of origin
What is anaplastic?
Loss of adult cell features primitive in type
What does the cytoplasm of benign tumors look like?
- Well developed
What does the nucleus of a benign tumor look like?
- Regular and uniform between cells
- relatively small nucleus
- chromatin regular and evenly distributed
- nucleolus is not prominent
- mitotic figures are absent or rare
What does the nucleus of a malignant tumor look like?
- vary in size and shape
- relatively large
- hyperchromatic - more chromatin than normal, uneven distribution
What does the nucleus look like of a malignant tumor?
- Nucleoli prominent, may be multiple
- mitotic figures - often present due to rapid rate of division
What does the cytoplasm of a malignant tumor look like?
- Variable a mount between cells
- Usually scant - not as much as normal
What does a benign tumor look like biologically?
May retain some of the complex functions of tissue of origin
What does a malignant tumor look like biologically?
- Too undifferentiated to function normally
- all cellular efforts directed to growth and mitosis
Do benign tumors metastasize?
Do malignant tumors metastasize?
Yes but not all malignant tumors metastasize
When can benign tumors be dangerous?
- Where they are located (example - in the skull)
- accidental complication (example - trauma, infection)
- production of excess hormone (insulinoma)
Spread of a tumor from its original site to another site in the body that is not adjacent to the original site
What are the three different ways a tumor can spread (metastasize)?
- Circulatory system
- lymphatic system
- implantation (seeding)
How do tumors spread through the circulatory system?
- Tumor cells carried by blood
- like to lodge in filtering sites, especially lungs
- radiograph lungs to look for metastatic tumors
How do tumors spread through the lymphatic system?
- Carried by lymph fluid
- metastasis to local lymph nodes
- may biopsy local lymph nodes
How do tumors spread through implantation?
- Occurs when a tumor invades the surface of an organ, tumor comes into contact with a body cavity
- cells break off original tumor
- carried by peritoneal or pleural fluid to new sites - new tumors
- abdominal tumors can cause ascites
How can surgery cause a tumor to metastasize?
- Excision not wide enough and leave some behind
- drag tumor cells through normal tissue with scalpel
What are the steps to metastasis?
- Tumor develops a mass of cells with ability to metastasize
- mass of cells expands and invades blood or lymph vessels or enters a body cavity
- cells break off mass
- carried by fluid to distant sites (blood, lymph, body fluid)
- survive, grow at new site (escape immune system, formation of new blood vessels to support tumor growth)
What are the names if benign tumors?
- "Oma" - lipoma, fibroma
- "adenoma" - glandular origin
What are the different names for malignant tumors?
What is the origin of sarcoma?
- derived from mesenchymal tissue
- connective tissue, blood and lymph vessels, skeletal and smooth muscle
What is the origin of carcinoma?
- epithelial tissue
- derived from fetal epithelium
What is epithelial tissue?
- covering of external and internal surfaces of the body
- skin, lining of GI tract, glands, endothelium - inner lining of blood and lymph vessels, lining of heart
What is a malignant tumor of glandular origin?
Is there such a thing as an adenosarcoma?
What are the two exceptions to the rules of naming tumors?
- malignant melanoma
- lymphoma - malignant tumor of lymphoid cells
What are some other names of tumor types?
- mixed tumors
- tumors of lymphocytes
What are blastomas?
- malignant tumors composed of embryonic cells
What are polyps?
- any growth of mass protruding from a mucous membrane
- usually normal tissue, may be benign tumor
What are some locations of polyps?
- mucous membranes
What are the two base types of polyps?
What is pedunculated?
attached by a thin stalk
What is sessile?
What are papillomas?
- the common wart
- benign epithelium
Where are locations of papillomas?
- protrude from surface of skin
- inner surface of urinary bladder, mouth, larynx
Which species are papillomas more common in?
cattle and humans
What are mixed tumors?
have both mesenchymal and epithelial components
What are teratomas?
- tumors derived from germ cells (testis, ovary)
- develop into different tissues, randomly mixed
Are teratomas benign or malignant?
can be either
Are teratomas common in animals?
What is melanoma?
tumors of melanocytes - in skin
Which animals is melanoma the most common in?
dogs and grey horses
What are amelanotic melanomas?
- too undifferentiated to produce melanin
- usually highly malignant
Which species is lymphoma the most common in?
What are the different names of "tumors of lymphocytes"?
Which organs are involved in lymphoma?
- may be many
- may be just in blood
- lymph nodes, thymus, spleen, intestines, liver
Lymphoma can be caused by a virus in which animals? What viruses cause lymphoma?
- cats, cattle, chickens
- bovine viral leukosis
- avian leukosis virus
- rous sarcoma virus
What is leukemia?
- abnormal malignant cells in circulating blood
- may occur in lymphoma
- may have other blood cells involved