neoplasia

abnormal cell growth unresponsive to normal control mechanisms; arises due to mutations in genes that regulate cell growth

benign neoplasm

neoplasm that doesn't invade surrounding tissues

malignant neoplasm

invades other tissues (cancer)

oncology

study of tumors

Carcinogenesis

biological changes that lead to neoplasia

carcinogen

agent causing neoplasia

Which type of skin cancers are the most common?

Basal/squamous cell skin cancer; ~1 million/year in the US

polyp

adenoma protruding from the mucosal surface

Characteristics of benign tumors include...

• slow growth, does not invade other tissues
• good prognosis
• surrounded by a capsule of CT
• strong resemblance to cell type of origin
• highly differentiated uniform cell pop.
• normal nuclei and normal amount of chromatin
• few mitotic cells

• fast growth, poor prognosis
• invade and infiltrate surrounding tissue
• various degrees of deviation
• HIGH NUCLEAR:CYTOPLASM RATIO
• LOTS of mitotic cells.
• Can form metastases :(

metastasis

movement of tumor from one site to another

Dysplasia

• disorderly non-neoplastic cell proliferation, usually in epithelial tissue
• high nuclear:cytoplasm ratio

Carcinoma-in-situ

severe dysplasia involving the whole thickness of the epithelium

What causes neoplasia?

the accumulation of genetic mutations over time that leads to a loss of control of cell proliferation.

What are the three stages of carcinogenesis?

1. Initiation--primary genetic event leads to an abnormal cell

2. Promotion--proliferation of abnormal cells

3. Progression--includes heterogeneity and metastasis

What is a proto-oncogene and hwo does it lead to uncontrolled cell growth?

• proto-oncogene-->gene that codes for proteins that stimulate cell growth
• a mutated proto-oncogene gets activated and it's abnormal protein that is produced has activity that cannot be controlled, hence uncontrolled cell growth.

How does loss of a tumor suppressor gene lead to abnormal cell growth?

• protein products of tumor suppressor gene INHIBIT cell growth, so a loss of this gene would lead to cell growth in an uncontrolled fashion.
• Ex: Rb-1, p53, BRCA-1

Clinical manifestations of neoplasia include...

• progressive loss of body fat, weakness, anorexia, anemia
• paraneoplastic syndromes

What is a paraneoplastic syndrome?

• changes produced in tissue remote from the tumor/metastases
• Ex: endocrine
  • hormones produced by non-endocrine tissue
• Neurologic
  • Ab's cross-react w/ and destroy neural tissue
• Hematoloic:
  • Thrombosis
• Renal:
  • Glomerulonephritis