Exam 2 Flashcards
(89 cards)
Diseases of Immunity, Chapter 5
Adaptive Immunity: is a group of specific second-line defense responses that occur days to weeks after exposure to microbial agents during the innate immune response. It is highly specific to a particular genera or species of antigens.
-Mature B-lymphocytes are activated by a specific antigen-binding molecule on its membrane, the antigen receptor is membrane-bound immunoglobulin. Mature T-lymphocytes express TCR which can recognize only antigens associated with MHC molecules resulting in self or non-self recognition.
-MHC I (CD8+) in all nucleated cells
-MHC II (CD4+) primarily in antigen presenting cells.
-ILCs (innate lymphocytic cells) are a heterogenous population of non-B and non-T lymphocytes that are not antigen specific. They can be polarized toward restricted cytokines (similar to T-helper CD4), but can be polarized to undesirable responses (dysregulated) also.
-Cytotoxic and non-cytotoxic types.
-Cytotoxic: resistance to viruses and neoplastic transformation, Induce chronic inflammation.
-Non-cytotoxic: resistance to bacteria, protozoan, allergic diseases, induce chronic inflammation, facilitate metabolic homeostasis.
Innate immunity: firs-line defense that occurs immediately or within a very short time (minutes or hours).
-Barrier systems: mucosal layer, pH, and body temperature, inflammatory and phagocytic responses.
-Key components: intact epithelial cells, neutrophils, monocytes, and tissue macrophages, innate lymphoid cells (ILCs), plasma proteins in the complimentary system
-Endothelial cells, phagocytic cells, and ILCs have PRRs, TLRs, that respond to PAMPs. These ligand-receptor interactions initiate the acute inflammation and recruitment of phagocytic cells from vasculature
-Recognition of intracellular and extracellular microbes leads to different types of responses, cell-intrinsic and cell extrinsic recognition mechanisms.
-ILCs located within the skin or mucosal of barrier systems act through PRR-PAMP
Hypercellular Lymph Node
Primary Lymphoid tissue: bone marrow, Peyers patches
Secondary lymphoid tissue: thymus, spleen, lymph nodes
Paracortical area: T-lymphocytes
Marginal and germinal zones: B-lymphocytes
Type I reaction
Most sensitive to anaphylaxis: Guinea Pig
Shock organs:
Dogs: liver
Rabbit: pulmonary vasculature
Sheep/cattle:lungs
Horses/cat/pig: lung and intestines
parenteral: IV, IM
Mast cells are easily identified by their abundant metachromatic cytoplasm granules (purple, usually).
-Acute inflammation and late-phase response
-Vasoactive amines
-Increased blood flow initially, vascular permeability, edema, smooth muscle spasms.
-Hypotension
-Tachycardia
-Hyperemia
-Pruritus
-Severe bronchospasm can lead to hypoxemia, edema of the respiratory airway.
Atopy: is the genetic predisposition to develop localized type I hypersensitivity called anaphylaxis to innocuous antigens. Ex: food allergies, asthma, allergic dermatitis and rhinitis.
Allergic Rhinitis of ruminants: can progress to type IV. Antigen inhalation, ingestion, or percutaneous absorption.
Type II
“Cytotoxic Reaction” Cell surface antigens.
-Minute to hours
a. Cell damage by complement: C3b opsonization, C5b MAC. Cell lysis
b. Antibody dependent cell mediated cytotoxicity opsonization
c. Antibody directed at cell surface resulting in cell dysfunction (either agonistic or antagonistic).
The biochemical properties of RBCs, platelets, and leukocytes make them susceptible to cytotoxic reactions. Commonly the case of transfusion reactions.
-Immune mediated hemolytic anemia disease of the newborn.
-Autoimmune forms of hemolytic anemia, agranulocytosis, and thrombocytopenia.
Clinicopathologic manifestation
-Hemolysis anemia
-Bleeding
-Vesiculobullous (disease of the skin)
-Vasculitis
-Muscle weakness, paralysis
-Abnormal erythropoiesis, anemia
-Subepidermal characterized by basement membrane clefts.
Type III Immune complex
When antigen is slight excess over antibody complex deposition, activation of complement vs a lot of antigen
Arthus reaction (localized) in the dermis
Formation of antibody-antigen complex that activate complement and result in tissue damage.
-“innocent bystander” the complexes become stuck to the cell or tissue.
-Involve IgM and IgG and occur within hours after exposure in a sensitized host.
- Immune complex formation
- Immune complex deposition
- Immune complex-mediated inflammation
A. Localized: Cutaneous Arthus. Acute inflammation, thrombosis, ischemia.
Blue eye (CAV-1) some forms of glomerulonephritis
Inhalation of fungus: emphysema, fibrosis, chronic obstrubtive pulmonary disease (COPD).
B. Generalized
-Systemic Lupus Erythematous
Vasculitis, glomerulonephritis, and arthritis = formation of micro thrombi by activation of coagulation cascade. Tissue Schemia, infraction, tissue necrosis.
Type IV (Delayed-type)
It is not dependent on antibody
-48-72 hours
Mediated by CD8+ cytotoxicity or CD4+ mediators (macrophages) to produce chronic inflammation.
-It is dependent on sensitized T-lymphocyte
Tuberculin: after an intradermal exposure a purified protein derivative of the tubercle bacillus would produce a localized type IV reaction on a previously sensitized host within 24-72 hours = Swollen and firm nodule.
-CD4+ & Th1 to MHCII: IFN-gamma, macrophage response
-CD4+ & Th2 to MHCII: IL-4, IL-5, Eosinophilic response
-CD8+ & cells to MHCI: Cytotoxic response
Example: Atopy, mites, pollen, organ transplant rejection. tuberculin response, intracellular organisms.
Clinopatholigic manifestations
-Granuloma formation
-Perivascular dermatitis
-Chronic arthritis with inflammation destruction of articular cartilage and bone
-Granulomatous enteritis
-Inflammation of graft tissue
-Uveitis
- Describe the features, pathogenesis and lesions of the four types of hypersensitivities and provide examples for each.
Immunity: defensive system recognition and protection from infectious pathogens and cancer. However, sometimes response illicit an inflammatory response that is not appropriate to the inciting antigen, these fall into three categories.
1. Hypersensitivity reactions
2. Autoimmune diseases
3. Immunodeficiencies
Immunity = beneficial
Hypersensitivity = harmful
Hypersensitivity reactions have two phases:
1. Sensitization phase: previous or prolonged exposure to the antigen
2. Effector phase: pathologic response, commonly inflammation or cell lysis.
Type I (15-30 minutes): immediate-type most often a result of IgE response directed against environmental or exogenous antigens (allergens).
-Release of vasoactive mediators from mast cells, resulting in edema of interstitial tissue.
-Can have systemic (anaphylaxis) or local (allergic dermatitis). Extrinsic asthma is another example. Urticaria, angioedema, flea bites, atopy.
Pathologic lesions:
-Vascular dilation, edema, smooth muscle contraction, mucus production, inflammation
Type II: cytotoxic hypersensitivity, most often occurs when IgG or IgM is directed against either al altered self-protein or a foreign antigen bound to a tissue cell.
1. Destruction of tissue or cell by antibody-dependent cellular cytotoxicity or complement-mediated lysis or
2. Altered cellular function without evidence of tissue damage
Ex: Pamphygus vulgaris, transplant rejection.
Pathologic lesions:
-Cell lysis, inflammation
Type III: Immune complex hypersensitivity caused by the formation of insoluble antibody-antigen complexes resulting in activation of the complement systems.
-Inflammatory reaction at the site of immune complex deposition.
-It can have generalized (rheumatoid arthritis and systemic lupus erythematosus) and localized (cutaneous Arthus reaction = Blue eye anterior uveitis in dogs) forms.
Pathologic lesions:
-Necrotizing vasculitis (fibrinoid necrosis), inflammation
Type IV: delayed-type hypersensitivity, results from activation of sensitized T lymphocytes to a specific antigen. The resulting response is either cytotoxicity or cytokines mediated macrophages produced chronic inflammation. It is the underlying mechanism for tuberculin testing in cattle for Bovine tuberculosis (Mycobacterium bovis) and allergic contact hypersensitivity, and granulomatous inflammatory responses.
Pathologic lesions:
-Perivascular cellular infiltrates, edema, cell destruction, granuloma formation.
Cytokines
Granulocytes in tissues
Cytokine-Related Disease
-Excessive elaboration of cytokines during bacterial septicemia and shock.
-Gram-negative endotoxin = IL-1 and TNF-alpha, fever, disseminated intravascular coagulation and shock.
-MHC II-TRC complex: severe damage to tissues and organ systems
Natural Killer cells
-Viral infections
-Activated by IFN-alpha, IFN-beta, released by virus infected cells, IL-12 released by macrophages, then they produce IFN-gamma = Th1 response.
- Describe the features of transplant rejections.
The MHC complex is essential component in humoral and cell-mediated immunity. Histocompatibility designation determines transplant tissue compatibility.
-The repertoire of MHC molecules is genetically controlled and determines an individual’s ability to respond to a specific antigen.
-Three different kinds of genes that encode for MHC grouped according to their structure, tissue distribution, and function.
-Class I and II genes: encode cell surface molecules
-Class III genes: encode components of the complement system, enzymes 21-hydroxylase A and B, cytochrome p450, TNF-alpha and Beta, and heat shock protein 70.
-MHC I: all nucleated cells, major function present CTL (CD8+) antigen fragments.
-Antigen uptake by antigen-presenting cells by phagocytosis or endocytosis = peptide fragment presented.
-MCH II molecules: induction of Th-lymphocytes (CD4+).
The most common in VetMed is Kidney transplant grafts
- Direct pathway: CD8+ CTL recognizes allogenic MHC molecules expressed by antigen presenting cells within the graft (donor).
- Indirect pathway: CD4+, the CTLs do not directly kill graft cells bc they are only recognizing graft antigens, but facilitate the development of an antibody (humoral) response.
Rejections can be hyper acute, acute, or chronic.
- Describe the features of and diagnose these autoimmune diseases:
Systemic lupus erythematosus: systemic, undetermined cause
Discoid Lupus erythematosus: localized to skin
Rheumatoid arthritis
Sjögren-like syndrome
Inflammatory bowel disease
Vogt Koyanagi Harada Like syndrome
Systemic Lupus Erythematous: multi-systemic including the skin
-Type III: forms immune complexes
-Glomerulonephritis, vasculitis, dermatitis.
-Production of antibodies directed against a wide array of normal tissue and cellular components.
-ANA predominant (Antinuclear Antibody) is directed against nuclear antigens, and cytoplasmic components which are neither organ specific nor species specific.
-RBCs cell surface antigens
-Affects: mice, horses, dogs, cats, snakes, iguanas.
-Average age of diagnosis is approximately 5 years
-40% fatal within 1 year
-Supportive care
-Exacerbated by sunlight
Breeds
-Beagle, Shetland sheepdog, German Shepherd, Old English sheepdog, Irish setter, Poodle.
-Siamese, Himalayan and Persian Cats predisposed.
Lesions
-Fever, non erosive poly arthritis, glomerulonephritis, mucocutaneous lesions, lymph node and spleen enlargement, hematologic abnormalities (anemia, thrombocytopenia, leukopenia).
Discoid Lupus Erythematous: localized to the skin
-Tx: sunscreen, glucocorticoids, VitE, Niacinamide, tetracycline.
-Low morbidity (good prognosis)
-Mostly dogs
-Depigmentation, rythma, scaling, erosion, ulceration, crusting.
-Skin of the nasal plant, nose, less commonly oral mucosa.
Rheumatoid arthritis
-Erosive lesion
-IgG antibodies
-Most species
-Rare
-C/S: lameness, joint laxity, Rheumatoid Factor (RF) anti-IgG antibody
-Chronic, sterile, erosive poly arthritis PANNUS (is an abnormal layer of fibrovascular tissue or granulation tissue, joints and cornea) formation.
-Fibroblast in the pannus enzymatically degrade cartilage.
-The pannus may act as a physical barrier between synovial fluid and the cartilage, prevent deliver of nutrients to the chondrocytes.
Sjogren-Like Syndrome
-Viruses are suspected as causes
-Systemic autoimmune disease characterized by keratoconjunctivitis sicca, xerostomia, and lymphoblasmacytic adenitis.
-Dry eyes, dry mouth, gingivitis and stomatitis.
-Inflammation of the salivary gland.
Clinical pathology
-Hypergammaglobulinemic
-Might have an ANA titer
-Might have a positive RF
Inflammatory Bowel Disease
-Cats, dogs
-Basenji, GSD
-Microscopic: lymphoplasmacytic enteritis
-Can lead to malabsorption and chronic PLE
-Cats may be caused by dietary antigens, may progress into lymphoma.
Vogt-Koyanagi
-Targets uveal and dermal melanocytes
-Akitas, Huskies, Alaskan Malamutes, Samoyeds, other breeds
-Breakdown of blood-retinal barrier, exposure of retina to specific antigen production of anti-retinal antibodies = blindness.
-Skin lesions mediated by T cells, macrophages (Th1), Ocular Th2 with B cell
-Clinical syndrome of dermal depigmentation and severe generally bilaterally symmetric uveitis is distinctive.
- Describe tolerance in regards to autoimmune diseases
Immune response to self-antigens
Loss of immunologic tolerance to self-tissue pr cellular antigens and it is characterized by abnormal or excessive activity of self-reactive immune effector cells.
Autoimmunity can be organ specific, localized, or systemic. Autoantibodies or self-reactive T-lymphocytes can cause the problem.
Alternating clinical disease and convalescence
-Immunologic tolerance is described as the failure of the immune system to respond to a specific antigen after previous exposure to that antigen. It is an absence of a functional response rather than a lack pf any response at all. The development of autoimmunity can be simply described as an scape from the mechanism by which self-tolerance is maintained.
-Deletion, energy, and suppression mechanisms.
Deletion: eliminating self-reactive T-lymphocytes in the thymus = CENTRAL TOLERANCE.
PERIPHERAL TOLERANCE: mature cells exposed to antigens in the peripheral tissues. The most likely to influence autoimmunity
-Anergy: Functional activation of lymphocytes that encounter antigen. Requires co-stimulation protein from APC; no co-stimulatory protein = anergia T cell.
-Suppression: Cross regulation of CD4+ Th1 responses by T-reg lymphocytes. Inhibition of lymphocyte activation
-Antigen Sequestration: (Testis, eyes, and brain = immunological privilege sites). BBB, absence of lymphatic drainage, or limited MHC expression. If antigens released as a result of trauma or infection, then severe immune response occurs.
- Describe the features of and diagnose these immunodeficiency syndromes:
a. SCID
b. Agammaglobulinemia
c. Chédiak-Higashi Syndrome
d. LeukocyteAdhesionDeficiencies
Immunodeficiency Syndromes
*Failure of the immune system to protect the host from infectious organisms or the development of cancer.
Primary = genetic or congenital
Secondary = loss of immune function due to infections, malnutrition, irradiation, chemotherapy.
SCID
-Severe combined immunodeficiency disease
-Primary immunodeficiency
-Deficiency in humoral and cell mediated immunity
-Defects in T-l ymphocytes or T & B. If severe Lymphoid Stem Cell defect.
-Common sequelae: fungal or viral infections. Bacterial if nor reliant on passive humoral immunity
SCID in Horses
-Autosomal recessive in Arabian (or cross) breed.
-Severe Lymphopenia
-At birth deficient in IgM
-Microscopically profound lymphoid hypoplasia of primary and secondary lymphoid tissue.
-Lymph nodes lack lymphoid follicles, plasma cells, and corticomedullary differentiation.
-Spontaneous mutation in gene encoding catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is required for the recombination of immunoglobulin heavy chain and TCR genes.
-Jack Russell Terries have similar mutation SCID
SCID dogs
-Basset hounds X-linked defect (XSCID)
-Lymphopenia with increased number of B-lymphocytes and few to no T-lym
-Not as profound as in horses
-At 6-8 weeks they develop recurrent infections of the skin
-Hypogammaglobulinemic with normal IgM and decreased IgA, IgG.
-Mutation on common gamma subunit of IL-2, IL-4, IL-7, IL-9 and IL-15. They can’t class switch to IgA.
SCID Mice
-Autosomal recessive
-Absence of mature B and T lymp
-Susceptible to infection but can be housed in ‘sterile’ facilities to keep alive longer (lab animal)
Agammaglobulinemia
-Primary (congenital)
-Inability to produce immunoglobulins and absence of mature B lymphocytes and plasma cells
-Thoroughbreds, quarter horses, standardbred breeds of horses.
-X-linked trait
-Microscopically and absence of plasma cells, primary follicles, and germinal centers in LNs.
Lesions
-Extracellular bacterial infections of the joints and respiratory system
-Chronic bacterial disease
-Pneumonia
-Arthritis
-Enteritis
-Dermatitis
-Laminitis
Chediak-Higashi Syndrome
-Cats, cattle, killer whales, beige mice, rats, Aleutian minks.
-Inherited autosomal recessive
-Defective lysosomes, melanosomes, platelet-dense granules, and cytolytic granules.
-Mutation of Last gene
Manifestation/lesions
-Hypopigmentation
-Bleeding tendency, platelet count normal, but defective.
-Ocular abnormalities
-Recurrent infections
-Hallmark: presence of enlarged granules within melanocytes or cytoplasmic granules
LAD
-Primary immunodeficiency disease
-Inability of leukocytes to migrate from circulation to sites of inflammation
-Recurrent bacterial infections
-Autosomal recessive trait
-Irish setter, Holstein cattle most affected.
-Leukocytosis with marked neutrophilic
-Defective expression of Beta-2 integrins
-Death at 6-7 its or both
-Pictures of inflamed gums, with bacterial infection
- Describe the characteristics of the different types of amyloidosis in domestic species.
Amyloid Light Chain (AL) derived from immunoglobulin light chains of plasma cells.
-Neoplasm of plasma cells present, myeloma, extra medullary plasmacytoma or multiple myeloma.
-Broad spectrum of clinical and pathological conditions with the deposition of amyloid material
-Amyloid is a pathologic proteinaceous substance of different chemical properties with an identical conformational property of forming a B-pleated sheets of non-branching fibrils.
-Improper folding deposition in blood vessels, basement membranes, spaces of dissent, spleen. Kidney = glomerulonephropathy = protein loss.
Amorphous, eosinophilic, hyaline, extracellular substance. Progressive accumulation causes pressure atrophy of adjacent cells and tissue.
Congo Red Stain = Red-orange color viewed by polarized light (apple green perfringence)
-AL amyloid: secreted in B cell proliferative disorders
-AA amyloid: liver secrets SAA during inflammation. AA synthesized from SAA.
Hereditary Amyloidosis: Shar Pei, Abyssinian cats.
Reactive Systemic Amyloidosis
-Most common form in animals
-Often secondary to chronic inflammation
-No underlying disease found, prolonged increased serum concentration of SAA protein. Siberian tigers, captive Cheetahs.
- Summarized the ways to diagnose amyloidosis.
Amorphous, eosinophilic, hyaline, extracellular substance. Progressive accumulation causes pressure atrophy of adjacent cells and tissue.
Congo Red Stain = Red-orange color viewed by polarized light (apple green perfringence)
Neoplasia
1.Define:neoplasm,benign,malignant,metastatic,anaplasia,hyperplasia,metaplasia,dysplasia, hypertrophy
2. Name a neoplasm based on its location and morphologic features. Outline the location and morphologic features when given the name of a neoplasm.
3. Describeandgiveexamplesoftransmissibletumors.
4. Classify a neoplasm as being benign or malignant based on gross and histopathologic features.
5. State the role of tumor suppressor genes (p53, RB) in neoplasia. Describe characteristics of labile/stable/permanent cells in relation to the cell cycle
6. DescribehowtocountmitoticfiguresinanH&Emicroscopicfield.
7. Identify and describe the steps of tumor development (Multistage Carcinogenesis)
8. Summarize lymphatic, hematogenous, and transcoelomic (carcinomatosis) metastasis.
9. Describe methods in which tumor cells manipulate the immune response
10.Define: cancer stem cells, tumor-initiating cells, stroma, angiogenesis, paraneoplastic effects, cachexia, functional endocrine tumors, humoral hypercalcemia of malignancy, hypertrophic osteopathy. Give examples of paraneoplastic effects.
11.Describe the differences and causes of Dystrophic and metastatic mineralization
12.List the types of oncogenic viruses and the tumor(s) they cause in the domestic species.
13.Describe the steps in diagnosing cancer and recommend the best diagnostic tests depending on the patient’s circumstances.
14.In your own words, explain: ancillary diagnostic tests: including differences between cytology, histopathology, special staining, clonality assays, molecular diagnostic techniques, grading, staging, surgical margins.
1.Define:neoplasm,benign,malignant,metastatic,anaplasia,hyperplasia,metaplasia,dysplasia, hypertrophy
2. Name a neoplasm based on its location and morphologic features. Outline the location and morphologic features when given the name of a neoplasm.
Neoplasia is the process of “new growth” “new” “plasma” in which normal cells undergo irreversible genetic changes, which renders them unresponsive to ordinary controls on growth exerted from within the transformed cell or by surrounding ‘normal’ cells.
- It can be malignant or benign.
-The cells expand beyond their anatomical boundary, creating microscopically and macroscopically lesions detectable = Neoplasms.
-Hyperplasia: increase in the number of cells in a tissue through mitotic division of cells, cellular proliferation
-Hypertrophy: increase in size through the addition of cytoplasm and associated organelles.
-Metaplasia: transformation of one differentiated cell type into another of the same lineage
-Dysplasia: is an abnormal pattern of tissue growth and usually refers to disorderly arrangement of cells within the tissue.
-Anaplasia: describes loss of cellular differentiation and reversion to more primitive cellular morphology, often irreversible progression to neoplasia.
Neoplastic cell lineage, Tumor Types
Mesenchymal (Round cells):
Bening tumors suffix -oma to the name of the cell of origin. Thus a fibroma is a benign tumor of fibroblast origin. Malignant suffix-sarcoma (fleshly growth). Fibrosarcoma is a tumor composed of malignant fibroblasts.
The cells of the hematopoietic system are also mesenchymal; thus tumors arising from these cells are sarcomas. Ex: malignant tumor of lymphocytes = lymphosarcoma, short is lymphoma.
a. Fat/adipocytes
b. Fibroblasts
c. Smooth/striated muscle
d. Astrocytes (nervous)
e. Monocytes (muscle)
f. Osteocytes
g. Chondrocytes
Round Cell Tumors
-T and B lymphocytes
-Mast cells
-Histiocytes
-Transmissible venereal tumors
-Plasma cells
Nomenclature
-Plasma cells: Plasmacytoma (benign) Multiple Myeloma (malignant).
-Histiocyte: Histiocytoma (benign) Histiosarcoma (malignant)
-Mast cell: Grade 1-2, or 1-3. >3 bad.
-Transmisible Venereal Tumors: a. Spontaneous regression (within 6mts), indolent growth; or very rarely progressive growth with metastasis.
-Tasmanian Devil Facial Tumor: similar to TVTs. Spread by biting (males especially)
Epithelial
Benign
-Adenoma: arising from glandular epithelium like mammary epithelium or tissue that exhibits a tubular pattern microscopically, such as renal tubular adenoma.
-Papilloma: usually exophytic (growing outward) from a cutaneous or mucocutaneous surface.
-Polyp: is a grossly visible benign epithelial tumor projecting from a mucosal surface, used interchangeably with papilloma.
Malignant
-Carcinomas: may contain nests, cords, islands of neoplastic epithelial cells. Invasive and can metastasize.
Examples: hepatocellular carcinoma, hepatocellular adenoma.
Scirrhous
-Others: nervous, undifferentiated (anapestic) and Mixed tumors.
Mixed Tumors
Mixed Tumors
-Tumor containing multiple cell types.
-Believe to arise from a single pluripotent or totipotent stem cell capable of differentiating into a variety of more mature cell types
-Example: mammary gland tumor of dogs typically contains a variable mixture of neoplastic epithelial or glandular elements. -Variable mixture of neoplastic epithelial or glandular elements (luminal epithelium and myoepithelium, mesenchymal elements: fibrous connective tissue, fat, cartilage, and bone)
Teratomas and Teratocarcinomas
-Arise from titopotential germ cells, three embryonic cell layers and thus composed of a bizarre mixture of adult and embryonic tissue types.
Bening Tumors, Malignant Tumors & Tumor-like lesions
Bening tumors
-Do not invade surrounding tissue (well demarcated, +/- capsulated)
-Do not become metastatic (usually)
-Can become malignant
-Composed of well differentiated cells
-Expansile, compress adjacent tissues
-Slow growing
One criteria does NOT indicate benign, more is better!
Malignant Tumors
-Poorly demarcated, unencapsulated
-Invade surrounding tissues, +/- hemorrhage and necrosis
-Often stimulate angiogenesis
-More likely to become metastatic
-Cells become poorly differentiated, +/- anapestic
-Rapid growth
Always use multiple criteria to come up with a more accurate diagnosis of whether benign or malignant*
-Example criteria under the scope: anisocystosis (cell size), anisokaryosis, cytomegaly, cellular pleomorphism (shape), well/poorly differentiated, anisokaryosis, karyomegaly, mitotic figures (rare, frequent, bizarre), multiple nuclei.
40x + 10x = 400x. 7-10 fields of view average! The more you look at the better the average you get! more representative sample!
Tumor-like lesions
-Nonneoplastic growths when examined microscopically.
-Example:
Hamartomas are disorganized but mature mesenchymal or epithelial tissues found in their normal anatomic location
-Many of Hamartomas consist of abnormal proliferation of blood vessels, may be the result of aberrant differentiation in development rather than true neoplasia
Choriostoma: “normal” tissue in an abnormal location. AKA “Ectopic”.
-Dermoid, a mass consisting of mature skin cell and adnexa, found in an unusual sites including the cornea.
Tumor-like Lesions
Harmatomas
Odontomas
Neoplasm Nomenclature examples
Neoplasm Nomenclature examples
Lymphoma (lymphosarcome)
Squamous cell carcinoma
Cell division, Rb, p53
Liable/Stable and Permanent Tissues
a. Liable: repeated dividing
b. Stable: “quiet” but can divide
c. Permanent: non dividing
Normal cell division is largely controlled by soluble or contact-dependent signals from the microenvironment that either stimulates or inhibit cell division. An excess of stimulators or deficiency of inhibitors leads to net growth.
Neoplastic Transformation
- Initiation: first step in carcinogenesis is introduction of irreversible genetic change into normal cells by action of mutagenic initiating agent or initiator, which can be chemical or physical carcinogens that damage DNA.
- Promotion: the outgrowth of initiated cells in response to selective stimuli, mostly promoting agents or promoters driving proliferation. Tumor progression is initially benign. Papillomas can regress.
- Progression: benign tumor evolves into increasingly malignant tumor during malignant transformation and can become metastatic. Benign-malignant-metastatic
Latency: time before a tumor is clinically detectable. Smallest size considered is 1cm. May have already divided 30 times!. Growth appears rapid after that bc only 10 subsequent cycles are required to convert a 1g tumor into a 1kg tumor!
Mitosis: Prophase, Metaphase, Anaphase, Telophase.
Stages
G1: presynthetic
S: DNA synthetic
G2: premitotic
M: mitotic
Quiescent cells are in physiological state G0
-In response to DNA damage even actively dividing cells undergo cell cycle arrest, usually at one of several cycle checkpoints.
-Cell cycle arrest is initiated by p53 (multifunctional tumor suppressor gene product 53). It gives the cell time to repair DNA damage.
-Many neoplastic cells do not respond to extrinsic or intrinsic signals directing them into G0 and no longer express functional p53. Thus, they continually move through the cycle and progressively accumulate mutagenic DNA.
-Because DNA replication machinery is unable to duplicate the extreme ends of DNA templates, the telomeres that form the ends of chromosomes are shortened at each cell division. Very short telomeres trigger cellular senescence in normal cells. Neoplastic cells regain the ability to produce telomerase and replicate their telomeres, escaping senescence = immortality.
Apoptosis: DNA damage induces apoptosis triggered by p53. Neoplastic cells lack expression or inactivate p53. Occurs from withdrawal of growth factors. Binding of death receptors (Fas ligand and TNF-alpha). Hypoxia or DNA damage trigger. T lymphocytes and NK cells stimulation
Checkpoints
-G1/S
-G2/M
Tumor Suppressor Genes
-p53: if unable to repair, it activates BCL2 associated X protein (BAX). Pro-apoptotic molecule following DNA damage. Target gene p21. G1-S, G2-M
-Retinoblastoma gene (RB): inactive gene allows for cell to proceed through G1/S phase