W7: Ch.4. Neoplasia Flashcards
Proliferation of normal cells is regulated by
- genetic program of each cell
- signals tranmitted from one cell to another by direct contact
- various substances that growth promoting or growth inhibiting effects
what is differentiation?
Selective Activation of genes- typically associated with supression of other genes
Proliferation of neoplastic cells
Autonomous - independent of growth factors and stimuli that promote the growth of normal cells
Excessive-
Disorganized- do not follow the rules governing the formation of regular tissues
Most important classification of tumors
Clinical: clinical presentation and outcomes
Histological: based on microscopic examination of tumors
Clinical Classification of Tumors
Benign: limited growth potential, good outcome
Malignant: Grow uncontrolably and kill the host
Macroscopic features: Benign vs. Malignant
Benign: Sharply demarcated from normal tissue, and are often encapsulatated. Benign tumors have expansive growth, and often compress the normal tissue which undergoes atrophy and fibrosis, forming a pseudocapsule. Can be removed easily.
Malignant: lack a capsule and not clearly separated from normal tissue. Invade normal tissue by infiltrating. Like roots from trees. Not removed as easily.
Microscopic Features: Benign Vs. Malignant
On microscope, Benign cells resemble the tissue from which they have arisen. High degree of differentiation.
Malignant cells show anaplasia- they exhibit new features not inherint to the tissue of their origin. Undifferentiated.
Cellular Features: Benign vs. Malignant
-Benign tumors are composed of uniform cell population: all the cells have approximately the same features. Well developed cytoplasm and organelles, nuclei resembling their proginator cells. Regular, even distribution of chromatin.
Malignant Tumors: heterogeneous cell population and nuclear pleomorphism (varying size and shape of tumor cell nuclei). Little cytoplasm, and reduced organelles. Nucleus is larger. Hyperchromatic, with chromatin distributed unevenly. and more cells undergoing mitosis.
Chromosomal Studies: Benign vs. Malignant
Benign tumors usually have normal # of chromosomes
Malignant are aneuploid (deletions, translocations) due to disorderly mitoses
Biologic features: Benign vs. Malignant
- well differentited cells of benign tumors may retain function of the normal cells in their tissue of origin
- Malignant cells have no differentiation and no specialized function. Their entire metabolism is geared towards rapid growth and replication
Describe metastasis
Process by which a tumor cells moves from one site of the body to another
-only malignant can metastasize
What is the process of tumor dissemination?
- through lymphatics
- through blood (hematogenous spread)
- through seeding of the surface of body cavities
What is the metastatic cascade?
What must tumors do at their new site in order to survive?
-Form their own blood supply- angiogenisis
How are tumors named?
According to the tissue type that they resemble the most
-connective tissues, muscles and bones (-oma)
fibroblasts= fibroma
lipocytes-lypoma
bone cells=osteoma
Comparison of normal and malignant cell: image
