neoplasia outline notes - pathology

7/28/2019 Neoplasia outline notes - Pathology

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I. IntroductionA. Abnormal growth disease of tissue stem cells that fail to differentiate normally

1. Control of growtha. Hormonesb. Growth factorsc. Receptors

2. Proto-oncogenes code for growth factors and their cellular receptorsa. Include epidermal growth factor (EGF)b. Platelet derived growth factor (PDGF)

3. Tumor suppressor genes act as brakes on the cell cycle, oppose proto-oncogenes4. Cell proliferation is balanced by apoptosis

II. Abnormalities of growthA. Atrophy of n organ is decrease either in size or number of individual cells

1. Causes of atrophy (reversible)a. Disuseb. Denervationc. Loss of trophic hormonesd. Loss of nutrientse. Pressuref. Senile atrophy

B. Hypertrophy (increase size of cells) and hyperplasia (increased numbers)1. Causes of hypertrophy and hyperplasia (both reversible)

a. Physiological adaptation to increased demandi. Ex. Muscle working against load, hormonal effects on breast I

pregnancy

b. Pathological occurs in the absence of a n appropriate functional demandi. Ex: sustained endometrial hyperplasia, bilateral adrenal hyperplasia

due to ACTH)

C. Metaplasia abnormality of cellular differentiation1. One mature cell is replaced a different type of mature cell2. New metaplastic tissue appears structurally normal but is in wrong place3. Occurs after an abnormal growth stimulus or chronic irritation4. Reversible5. Squamous metaplasia = most common

D. Dysplasia abnormality of both differentiation and maturation1. Characteristics of dysplasia (reversible)

a. Nuclear abnormalitiesi. Increased nuclear/cytoplasmic ratioii. Hyperchromatismiii. Nuclear membrane irregularities

b.

Cytoplasmic abnormalitiesi. Failure of normal differentiationc. Increased rate of cell multiplicationd. Dysplasia graded as mild, moderate or severe

2. Significance of dysplasiaa. Epithelial dysplasia is a premalignant lesionb. Carcinoma in situ = severe dysplasia (show all features of cancer except

invasion)

c. Risk of developing invasive cancer varies withi. Grade of dysplasiaii. Duration of dysplasia


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iii. Site (risk greater in bladder than cervix)3. Difference s between dysplasia and cancer

a. Lack of invasiveness = excision of dysplastic area is curativeb. Reversibility (dysplasia is reversible, cancer is not)

4. Diagnosis of dysplasiaa. Gross examination usually no gross abnormalityb. Microscopic examination

i. Cell smears cytologyii. Tissue obtained by biopsy histology

c. Diagnosis important to prevent later development of cancerd. Must be distinguished from inflammatory, degenerative and regenerative

changes which may show some cellular disorganization

III. NeoplasiaA. Definition of neoplasia (not reversible_

1. New growth abnormality of cellular differentiation, maturation and control ofgrowth

2. Commonly form masses of abnormal tissue3. Cancer = general term for a malignant neoplasm

B. Classification of neoplasms1. Biological behavior: benign vs malignant2. Cell or tissue of origin (histogenesis)3. Other features, such as site, embryological derivation, gross features

C. Biologic Behavior1. Benign neoplasm grows slowly, encapsulated and does not spread2. Malignant grow rapidly, infiltrate surrounding tissue and metastasize3. Classification based on several factors

a. Rate or growth malignant generally grow more rapidlyi. Clinical observationii. Microscopic examination

b. Size not helpfulc. Degree of differentiation denotes the degree to which the neoplasm

resembles the normal tissue in questions

i. Benign well differentiatedii. Malignant well, moderately, or poorly differentiatediii. Anaplastic no resemblance to normal tissue (very poorly

differentiated)

d. Histological cytologic features of malignancyi. More densely cellular, higher mitotic rate, abnormal mitosesii. High nuclear/cytoplasmic ratioiii. Variable appearance from cell to cell, abnormal differentiation,

necrosis frequente. Changes in DNAi. Abnormalities increase with the degree of malignancyii. Malignant cells = hyperchromaticiii. Cytogenetic studies show aneuploidyiv. Molecular methods reveal abnormalities of oncogenes/tumor

suppressor genes in all cases

f. Invasion and metastasis malignant onlyi. Invasion local spreadii. Metastasis distant spreadiii. Benign have smooth capsule and not invasive


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iv. Malignant have no capsule, irregular and are invasiveg. Metastasis absolute evidence of malignancy

D. Cell or Tissue of Origin (Histogenesis) Neoplasms classified according to their potentialfor cellular development

1. Neoplasms of totipotent cells develop from residual germ ellsa. Germ cell neoplasm may show minimal differentiation, resemble trophoblast

yolk sac or somatic structures.

b. Teratomas contain elements from all three germ layersi. Mature (well-differentiated, usually benign)ii. Immature (made up of fetal type tissues, malignant)

2. Neoplasms of pluripotent (usually embryonic) cells partially differentiated fetaltype stem cells

a. Blastomas resemble embryonic organs, occur in childhood, malignanti. Nephroblastoma, neuroblastoma, etc.

3. Neoplasm of Unipotent (differentiated) cells include most neoplasm of adultsa. Epithelial versus mesenchymal

i. Epithelial neoplasmsBenign

1. Adenomas (from epithelium within a gland)2. Papillomas (from surface of squamous, glandular or

transitional epithelium)

Malignant = carcinomas1. Adenocarcinomas (glandular epithelium)2. Squamous carcinomas3. Transitional carcinomas

ii. Mesenchymal neoplasmsBenign: cell type plus suffix oma (fibroma)Malignant: cell type plus suffix sarcoma (fibrosarcoma)

iii. Exceptions to rulesLymphoma, plasmacytoma, melanoma, glioma andastrocytoma are all malignantLeukemia rarely produce local tumors and classified by clinical

course and cell of origin

Certain mixed tumors appear to be composed of more than oneneoplastic ell type

Some neoplasms named after person who described themiv. Hamartomas and choristomas developmental anomalies, not true

neoplasm

Hamartoma composed of tissues that are normally present inthe organ in which it arises

Choristoma contains tissues not normally present in its siteof origin

E. Incidence and distribution of cancer in humans (pg. 10)F. Theories of Origin of Neoplasia (pg. 12)G. Agents Causing Neoplasms (pg. 16)H. Characteristics of Neoplasia (pg. 21)I. Effects of neoplasia on the host (pg. 24)J. Approach to Cancer DiagnosisK. Treatment of neoplasmL. Symptoms and signs of cancer


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M. Causes of death in cancer

neoplasia outline notes - pathology

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