Pathophysiology Neoplasia Notes

Neoplasia

"new growth" and an overgrowth of a tissue - neoplasm: neoplastic mass - tumor (abnormal swelling) term is now synonymous with neoplasia - oncology - study of tumors - neoplasms proliferate to form new tissue (irreversible) - they do not wait for signals from the body that the new tissue is needed - they ignore signals to stop dividing: become autonomous - they do not die off (apoptosis) to keep the number of total cells constant

Malignant Neoplasms

- contain cells that do not look like normal adult cells and lose cellular differentiation - "anaplasia" differentiation refers to the extent that the parenchymal cell resembles normal cells - malignant cells are also pleomorphic (marked variability of size and shape of cell and nuclei) - irregular or bizarre mitoses, cells divide rapidly - tumors grow quickly - the tumor does not have clear boundaries and sends "legs" to invade surrounding tissue - do not perform the normal functions of the organ - may secrete hormones associated with other tissues - can compress and/or destroy the surrounding tissues - cells secrete enzymes and can penetrate surround tissue and vessels - promote blood vessels growth to the tumor

Patterns of spread of malignant tumors

- direct extension: (invasion) into surrounding tissues - within body cavities (seeding): by penetrating the wall of an organ, move into a body cavity and spread throughout the area - lymphatic spread: lymphatic vessels similar to veins, easy to invade, lymph nodes are easily invaded and become secondary sites, sentinel node describes the initial lymphnode that is invaded, tumor can then enter into blood - hematogenous spread: usually starts at thin wall capillaries/veins, eventually leads to r atrium, then lungs, lodges in small vessels and the cell becomes actively invasive secreting enzymes that promote passage into lung tissue; liver is also common - hepatoportal circulation - venous draignage of GI tract

Leukemia

- neoplasms arising from blood forming tissues - precursors of white blood cells in bone marrow proliferate and crowd out normal blood forming cells - enter into the blood stream circulate in peripheral blood

Metastasis

cells in a primary tumor develop the ability to escape and travel in the blood or lymph - secondary site has same tumor cells as primary site - the secondary tissue is normal but, has tumor cells from the first site - these secondary deposits are called metastatic tumors

Characteristics of tumors: Benign

contain cells that look like normal tissue cells - slow growing: mitotic cells are very rarely present during microscopic analysis - may perform the normal function of the tissue (like secreting hormones) - this may lead to over secretion anatomy: - surrounding capsule of connective tissue - they retain recognizable tissue structure and do not invade beyond their capsule - generally are localized and remain in tissue they originated - though benign, they may cause problems through mass effect, particularly in tight quarters - they can damage nearby organs by compressing them

Diagnostic test

definitive diagnosis is by tissue biopsy or from blood smears or cytology - you must look at the cells - screening tests are recommended for most common types of cancers (PAP smear, mammography, colonoscopy, tumor marker tests) Prognosis: - the smaller and more localized the tumor the better the prognosis - staging and grading of tumors are systems used to prognosticate and design therapy protocols, stage describes the extent of spread in the body, grade considers the appearance of cells microscopically Treatment: - surgery, radiation therapy, chemotherapy, hormone and antihormone therapy, immunotherapy, combination therapy

Pediatric Neoplasms

ending in "-blastoma" resemble primitive embryonic tissues - retinoblastoma - neuroblastoma - hepatoblastoma - medulloblastoma

Carcinogenesis

initiation: initial mutation occurs promotion: mutated cells are stimulated to divide progression: tumor cells compete with one another and develop more mutations which make them more aggressive

Carcinomas

malignant tumors of the skin and epithelial lining of the gi and respiratory tract and glandular tissue - further designated by the type of epithelial tissue - squamous cell carcinoma - skin surface - basal cell carcinoma - deep layer of skin becomes neoplastic - adeno(gland)carcinoma of pancreas - transitional cell carcinoma of bladder

Sarcomas

malignant tumors that arise from connective tissue and supporting tissue - references a particular tissue of origin - ex: chondrosarcoma, osteosarcoma, fibrosarcoma

Exceptions

some terms do not follow the rules and are malignant even with the "oma" ending - lymphoma - malignancy of lymphoid tissue - melanoma - malignancy of melanocytes - glioma can be benign or malignant

Benign

suffix "oma" is used with the tissue type benign tumors are generally named according to the tissues from which they arise - glandular - adenoma - fatty - lipoma - muscle - myoma - vascular - angioma - brain - meningioma some brains are based on structure, for ex. papilloma = warty type appearance

Genetic involvement

the autonomous growth of neoplastic tissue is based on defects in the genes that regulate the fine balance of cell production versus cell loss by apoptosis - DNA damage involving certain genes - Proto- Oncogenes: regulates normal growth function in cells, can mutate and can convert into an oncogene; oncogene: stimulates excessive cell growth "gene that causes cancer"

Etiology

there is no single mechanism by which a neoplasm arises - many different mechanisms give rise to neoplasms, and that is what makes diagnosis and treatment so challenging - all cancers involve the malfunction of genes that control cell growth and division Genetic alteration is the basis for the development of cancer

Carcinogens

these factors may act together or in sequence to cause cancer, ten or more years often pass between exposure to external factors and detectable cancer examples: - ultraviolet, x-radiation, gamma radiation: depends on dose, duration, and the body part exposure can take years to manifest damages. UV rays lead to DNA mutations, can give rise to squamous cell carcinomas and malignant melanomas - chemical carcinogens: directly damage DNA -> mutations -> cancer (tobacco -> lung cancer) - viral cause: viruses can transform cells - interact with chromosomal DNA - genetic factors: women from population groups with a higher frequency of mutations in the breast cancer susceptibility genes

Malignant

tumors are classified according to the embryonic origin of tissue - cancer: malignant neoplasm - malignancy = potential to spread quickly and throughout the body resulting in death

Clinical manifestations

variable depending on type and site of neoplasia - local damage is confined to one area of the body - systemic-lesions are distributed throughout the body - evidence of mass - pain - local destruction of tissue, invasion of nerve, by obstructing hollow organs, causing inflammation and pain - obstruction from within lumen or organ or vessel or external compression - hemorrhage - ulceration secondary to destruction and blood vessel involvement - pathologic fractures: primary bone tumor, common site for metastasis in lung, breast, and prostate cancer, weakening and destruction of bone results in fractures - infection: common complication of neoplasia, most common cause of death - cachexia: generalized muscle wasting, anorexia, cancer cachexia syndrome: weight loss, muscle wasting, anorexia & anemia