Exam V: Neoplasia Flashcards
Neoplasia
Defined as a disorder of cell growth
Triggered by a series of acquired mutations affecting a single cell and its clonal progeny
Causative mutations give the neoplastic cells a survival and growth advantage
Resulting in excessive proliferation that is independent of physiologic growth signals (autonomous)
Two Components of Neoplasms
Two basic components:
- Neoplastic cells- constitute the tumor parenchyma
- Reactive stroma- CT, blood vessels, and cells of the immune system
Classification of tumors and their biologic behavior are primarily based on the parenchymal component (cell type present)
Growth and spread of tumors are critically dependent on their stroma because blood vessels and support are vital to growth
Desmoplasia
Parenchymal cells stimulate the formation of abundant collagenous stroma
Have neoplastic cell nests and the body is trying to get rid of it
The parenchymal neoplastic cells will stimulate tissues around it
Abundant blue/gray surrounding tumor malignant islands = desmoplastic response; body’s way of reacting to the cells of the tumor
Benign Tumors
Localized, innocent growth that will not spread to other sites
Amenable to local surgical removal
Designated by attaching the suffix-omato the name of the cell type of origin
Mesenchymal tumors:
Fibroma - benign tumor arising in fibrous tissue
Chondroma- benign cartilaginous tumor
Nomenclature of benign epithelial tumors—complex classification:
Some are classified based on their cells of origin, microscopic pattern, or macroscopic architecture
Adenoma- benign epithelial neoplasms derived from glands; may or may not form glandular structures
Papillomas vs. Polyps
Papillomas: benign epithelial neoplasms; produce microscopically/macroscopically visible fingerlike or warty projections from epithelial surfaces
Polyp: can be benign or malignant
Macroscopically visible projection above a mucosal surface that projects into the lumen
If it has glandular tissue—-termed an adenomatous polyp
Mushroom like appearance
Cystadenomas and Papillary Cystadenomas
Cystadenomas: large benign cystic masses, such as in the ovary; filled with serous fluid usually within the ovary or testicle
Papillary cystadenomas: benign papillary patterns that protrude into cystic spaces
Malignant Tumors: Leukemia vs. Lymphoma
Leukemias(WBC): malignant tumors arising from blood-forming cells
Lymphoma: malignant tumors of lymphocytes or their precursors
Malignant Tumors: Carcinoma
Carcinomas: malignant neoplasms of epithelial cell origin
Derived from any of the three germ layers (endo, meso, or ectoderm)
Squamous cell carcinoma: tumor cells resemble stratified squamous epithelium
Adenocarcinoma: lesion in which the neoplastic epithelial cells grow in a glandular pattern
Malignant Tumors
Collectively referred to ascancers that adhere to any part that they seize on in an obstinate manner
Invade and destroy adjacent structures
Spread to distant sites (metastasize) to cause death
Sarcoma
Sarcomas (sar = fleshy): malignant tumors arising in solid mesenchymal tissues
Examples:
Fibrosarcoma, chondrosarcoma, leiomyosarcoma, rhabdomyosarcoma
Mixed Tumors
Divergent differentiation of a single neoplastic clone
Example: mixed tumor of salivary gland
Epithelial components scattered within a myxoid stroma
May contain islands of cartilage or bone
All of these elements arise from a single clone capable of producing both epithelial and myoepithelial cells
Preferential term: pleomorphic adenoma
Can be benign or malignant
Teratoma
Contains recognizable mature or immature cells/tissues
Tissues belong to more than one germ cell layer, sometimes all three
Originates from totipotential germ cells
Normally present in the ovary and testis
Differentiate into any of the cell types found in the adult body
May give rise to neoplasms: bone, epithelium, muscle, fat, nerve, and other tissues
Dermoid Cyst
Ovarian cystic teratoma
Differentiates principally along ectodermal lines
Cystic tumor lined by skin replete with hair, sebaceous glands, and tooth structures
Harmartoma
Hamartoma: disorganized benign masses composed of cells indigenous to the involved site
Choristoma
Heterotopic rest of cells
Example: small nodule of well-developed and normally organized pancreatic tissue
Found in the submucosa of the stomach, duodenum, or small intestine
Caused by cells left behind during development that formed into the structure it was supposed to be
Differentiation vs. Anaplasia
Differentiation
Extent to which neoplastic parenchymal cells resemble the corresponding normal parenchymal cells morphologically and functionally
Mitoses are usually rare and are of normal configuration
Anaplasia: lack of differentiation/ poorly differentiated
cells are regressing back to primitive appearance; must use stains to tell where cells came from
Lack of differentiation is considered a hallmark of malignancy
Pleomorphism
Variation in size and shape
Cells within the same tumor are not uniform
Range: small cells with an undifferentiated appearance to tumor giant cells
Mostly associated with malignancy, but can be benign
Abnormal Nuclear Morphology
Nuclei are disproportionately large for the cell
Nuclear-to-cytoplasm ratio may approach 1 : 1
Normal 1 : 4 or 1 : 6
Nuclear shape–variable and irregular
Chromatin: coarsely clumped when normally distributed along the nuclear membrane
Hyperchromatic
Abnormally large nucleoli
Mitoses
Reflects the high proliferative activity of the parenchymal cells in a tumor
Presence does not necessarily indicate malignancy
Indicative of rapid cell growth
Seen in normal tissues exhibiting rapid turnover
Epithelial lining of the gut
Nonneoplastic proliferations—hyperplasia
Atypical, bizarre mitotic figures:
Tripolar, quadripolar, or multipolar spindles
Morphologic feature of malignancy
Metaplasia
Replacement of one type of cell with another type
Found in association with tissue damage, repair, and regeneration
Replacing cell type is better suited to some alteration in the local environment
Example: Gastroesophageal reflux
Damages the squamous epithelium of the esophagus
Replacement by glandular (gastric or intestinal) epithelium
Dysplasia
“Disordered growth” Encountered principally in epithelia Loss in the uniformity of the individual cells Loss in their architectural orientation Considerable pleomorphism Large hyperchromatic nuclei Increased nuclear-to-cytoplasmic ratio
Normally more immature cells at basement membrane, and are larger; by the time you get to the surface of the cells, they should be thinned out and smaller from maturation
If this does not occur = dysplasia
Carcinoma In Situ
Dysplastic changes are marked and involve the full thickness of the epithelium
Lesion DOES NOT penetrate the basement membrane
Precursor to malignancy, HOWEVER, it does not always progress to cancer
Removal of inciting causes—may reverse
Mild to moderate dysplasia (not involving entire epithelium)
Dysplasia often occurs in metaplastic epithelium BUT…not all metaplastic epithelium is dysplastic