Neoplasia
Definitions
- Tumor- mass or lump
- Neoplasm- new growth; an abnormal mass of cells that exibits uncontrolled growth and proliferation and that persists after cessation of the stimulus that produced it.
- All neoplasms depend on the host for their nutrition and vascular supply
- Neoplasia- formation of a neoplasm
- Cancer- crab; malignancy
- Oncology- study of tumors
- Hamartoma- not a neoplasm; disorganized mass of normal tissue components
Characteristics of Benign and Malignant Neoplasms
Characteristic Benign Neoplasm Malignant Neoplasm
Rate of Growth slow may be rapid
Manner of Growth expansile, encapsulated, displacement infiltrative, non-encap, destroys
Metastasis absent often present
Effect on patient usu not serious; location dependent kill/progressive growth & spread
General
- first describe a benign or malignant tumor by the site, or tissue affected (gastric, uterine)
- Benign tumors end in -oma; EXCEPT FOR lymphoma which is malignant
- Blastoma is simply a tumor of primitive, incompletely differentiated cells
- There are some non-neoplastic masses like granulomas
Benign Tumors
- Benign mesenchymal tumors are classified according to parenchymal cell type
- Benign epithelial tumors are classified on various features
- cell of origin
- microscopic architecture
- Macroscopic or gross features
- Adenoma- glandular epithelium
- Papilloma- epithelial tumor that projects from a surface
- Polyp- epithelial tumors that proects from a surface but has a smooth or nodular surface
- Cystadenoma- adenoma that grossly looks cystic
- Teratoma- tumor that arises from germ cells and contains derivatives of different germ layers
Malignant Tumors
- Cancer- broad term
- Carcinoma- malignant tumor of epithelial origin, derived from any of the three germ layers
- Adenocarcinoma- glandular epithelium derived
- Squamous cell or epidermoid carcinoma- stratified squamous epithelium
- Undifferentiated carcinoma- no histologic features showing similarity to a specific type of epithelium
- Sarcoma- mesenchymal origin; usu fleshy because of conective tissue stroma
- Lymphoma- lymphoid cells in solid organs
- Leukemia- white blood cells in the bone marrow
- Malignant Melanoma- (melanocarcinoma)- melanocytes
- Carcinosarcoma- epithelial and stromal elements
- Malignant teratoma- more than one germ layer
- Many others
Behavior and Structure of Neoplasms
General Features
- divisions of neoplasms into malignant and benign is based on the biologic behavior of the tumor
- gross and microscopic appearance are the best means of predicting behavior
Terms
- Differentiation
- Extent to which tumor cells represent, structurally and functionally, the normal tissue
- Anaplasia
- Lack of differentation
- Pleomorphism
- Many forms (size, shape, appearance of cells)
- Carcinoma in situ
- Cellular features of malignancy, but no evidence of invasion through the baemant membrane
- Precursor to invasive carcinoma
- Invasive carcinoma
- Unless otherwise qualified, carcinoma = invasive
Features of BENIGN neoplasms
- Gross
- Roughly sperical, papillary of polyploid on a surface
- Circumscribed = not infiltrative
- Most are encapsulated
- Color and consistency resemble tissue of origin
- No metastases
- Microscopic
- Well- differentiated
- Orientation of cells normal
- Few mitosis or absent
- No invasive or infiltrative growth
Features of MALIGNANT neoplasms
· Gross
· Invasive fingers (crab legs)
· Tissue destruction
· Irregular outline
· Consistency varies
· Microscopic
· Anaplastic
· Nucleus is center of focus in cytodiagnosis of malignancy
· No one feature is pathognomonic of malignancy
· General Microscopic changes of malignancy
· Evidence of active cellular proliferation
· Nuclear hypertropy
· Multiple or prominent nucleoli
· Increased nucleocytoplasmic ratio
· Lots of mitotic figures
· Evidence of Abnormal cellular proliferation
· Pleomorphism
· Abundance of DNA in nucleus, clumping of chromatin, Hyperchromasia
· Nucleolus size, shape and #
· Cytoplasm size, shape and staining characteristic
· Abnormal mitotic figures
· Tumor Giant Cells
· Evidence of invasive growth
· Loss of normal cellular polarity and arrangement
· Loss of mutual adhesiveness
· Basement membrane penetration
· Infiltration of normal structures
· Evidence of loss of cellular specialization or differentiation
· Anaplasia
Patterns of spread
· direct extension
· invasion of adjacent structures or organs by direct tumor growth
· seeding or implantation
· cells can be spread in cavities by the cavity fluid
· can occur w/ benign and malignant neoplasms
· metastasis
· almost all cancers can metastasize
· malignant cells invade lymph channels or blood vessels through which they are carried to a new location where the cells can either invade or set up housekeeping in the microcirculation
- Lymphatic metastasis
- Most comon pathway
- Lymph node involvement usually follows the normal route of lymphatic drainage to regional lymph nodes
- Enlarged node may NOT contain tumor, just may be reactive
- Cut surface of tumor involved lymph node usually resembles primary tumor
- Hematogenous metastasis
- Carcinomas and sarcomas metastasize this way
- Liver and Lung are most frequent sites of hematogenous metastases
- Metastases can travel all over the body
Clinical Features of Tumors
Tumor-Host Interaction
- parasites
- 2 way actions
Effects of Neoplasm on Host
- compression or destruction of normal tissuesÞ interference of normal functions
- obstruction of hollow channel
- mucosal involvementÞirritation, coughing, indigestion, dysuria
- secondary infection
- hemorrhage
- hormonal secretion prevention
- rupture of tumor
- malaise and low-grade fever from necrosis and inflammatory reactions
- CANCER CACHEXIA- severe weight loss of lean body mass, anemia, and weakness that usually occurs in the late stages of a malignant neoplasm
- ORIGIN OF CANCER CACHEXIA
- Unclear
- Starvation, hypermetabolism, bleeding, pain, anxiety, depression
- High rate of body protein turnover
- Decreased appetite due to affect on hypothalamus
- NOT FROM NUTRITIONAL DEMANDS OF TUMOR!!!!!!!!!!
- Hormonal Secretion
- Examples
- Acromegaly from pituitary tumors
- Cushing’s syndrome from adrenal cortical tumors
- Hypertension with adrenal medulla tumors
- Hypercalcemia with parathyroid neoplasms
- Paraneoplastic syndrome
- unexplainable symptom complexes
- Example- hypercalcemia
Host defense against tumors
- TUMOR ANTIGENS
- Unsure if cancer cells have non-self identifiable antigens
- Certain cancers evoke a lymphatic response
- Immunosurveillance
- Also unsure if there is a self-policing component to the immune system
- Strongest evidence is increased frequency of cancers in immunodeficient hosts
- Most are lymphomas
- Most common forms (i.e. lung, breast, GI) are NOT increased
Laboratory Diagnosis of Cancer
Histologic and Cytologic methods
- most diagnosed this way
- sample must be adequate, representative, and properly preserved
- Cytology: rapid, inexpensive, less invasive, minor injury
- Surgical biopsy: less subjective; relationships of cells easily seen, size and location can be approximated
Ancillary Diagnostic Techniques
- Immunocytochemistry
- Ab are used to ID cell products or surface markers
- CD45- leukocytes
- Cytokeratins- epithelial cells and carcinomas
- Vimentin- mesenchymal cells and sarcomas
- Desmin- smooth and skeletal muscles
- GFAP- glial cells and gliomas
- Neurofilament proteins- neurons and paraganglia
- DNA probe analysis
- DNA flow cytometry
- Tumor markers
- Biochemical indicators of the presence of a tumor
- Can be ID in tissue and sometimes in serum
- Not used for primary diagnosis
Grading and Staging of Cancers
Grading
- Typically grading is clinical only and often more prognostic.
Staging
- Staging is most useful in determining management of the patient. For example, stage 4 (prolific) cancers are usually a contraindication for surgery.
- TNM cancer staging system
- Tumor size
- Lymph node involvement; number and distribution
- Metastases; grades hematogenous involvement
- Criteria commonly used
- Tumor size
- Growth (local)
- Lymph node metastases
- Distant metastases
Epidemiology of Cancer
Incidence of Cancer in the U.S.
- 22% of all mortality
- 2nd leading cause of death
- men (other than skin)- prostate, lung, colorectal
- women (other than skin)- breast, colorectal, lung, genital tract
- benign tumors are more frequent than malignant ones
Several factors influence the incidence of neoplasms
- Age
- Infants and preschool children
- Acute leukemia, neuroblastoma, retinoblastoma, rhabdomysarcoma
- Older persons
- Prolonged action of carcinogens
- Sex
- Cancer is more frequent in males
- Other than skin cancer, most frequent site in males- prostate
- Women- breast
- Race, geography, and habitat
- Environmental and cultural influences
- Heredity
Tags: Adenoma, cancer cachexia, Carcinosarcoma, Cystadenoma, granulomas, Leukemia, lymphoma, Metastasis, neoplasm, Papilloma, polyp, Teratoma, tumor
