LN 09 (Neoplasm) Flashcards
Classical neoplasm 3 features
- it is an excessive tissue growth
- it lacks responsiveness to control mechanisms
- it lacks continued dependence on the stimulus that initiated it
form of pathological hyperplasia
neoplasia
retrogressive change that is reversible and is
responsive to growth control mechanisms
hyperplasia
Neoplasia literally means “new growth”, and this tissue growth is called
neoplasm
a tissue swelling or mass that may or may not
be neoplasm
tumor
study of neoplasia
oncology
chemical messengers of density-dependent inhibition or contact inhibition of growth
chalones
process of normal cells losing their innate characteristics and become neoplastic cells
neoplastic transformation
Morphological characteristics of transformed cells
1) May or may not resemble their cell origin
2) Presents increased nucleus to cytoplasmic ratio, the nuclei being enlarged hyperchromatic and may be multinucleated
3) Chromosomes may present mitotic figures
4) They lack orientation to adjacent cells
5) Decreased rough endoplasmic reticulum and increased free ribosomes
Characteristics of transformed cells beside morphological changes (6)
- Transplantability
- Immortality
- Tumorigenicity
- Antigenic changes
- Karyotypic changes
- Biochemical changes
neoplasm containing tissue derived from more than one germ layer
Teratoma
neoplasm derived from one embryonic germ layer
mixed neoplasm
Based on the tissue origin, the neoplasm could be
epithelial, mesenchymal
inoffensive, grow slowly by expansion, circumscribed, does not undergo metastasis, few mitotic or apoptotic figures, and is rarely fatal
benign neoplasm
refers to those that are aggressive and potentially life threatening
malignant neoplasm
Benign neoplasms carry the suffix
oma
Benign neoplasms derived from glandular epithelia
adenomas
solid lobular pattern of growth and those with
recognizable acini, ducts and tubules
adenomas
adenoma forming cystic cavitation
cystadenoma
forms branching finger-like projections into the lumen
papillary adenoma
adenoma derived from ducts
ductular adenoma
neoplasms growing at the surfaces
polyps or papilloma
Malignant neoplasms of mesenchymal origin are called
sarcoma
Malignant neoplasms of epithelial origin are called
carcinoma
carcinoma forming recognizable ducts, tubules or acini
adenocarcinoma
fail to mimic their tissue origin sufficiently for them to be recognized
poorly differentiated sarcoma or carcinoma
well differentiated such that they resemble the tissue of origin both cytologically and architecturally
benign neoplasm
vary greatly in the degree of differentiation, and they usually exhibit anaplasia
malignant neoplasms
failure of cells to differentiate or loss of differentiation
anaplasia
one of the hallmarks and the most important morphologic feature of malignancy
Anaplasia
nuclei become large, hyperchromatic or vesicular, have abnormal shapes and may contain one or more prominent nucleoli
pleomorphism
anaplastic cells usually exhibit?
pleomorphism
Examples of well-differentiated neoplasms
- glandular adenomas
- endocrine adenomas
retain the functional characteristics of the
parent tissue, such that even their functional activity is intact
well-differentiated neoplasms
one of the basis on which the origin of neoplasms may be known
functional activity
precludes further mitotic division
full differentiation
contains a high proportion of cells unable to divide and so grow slowly
benign neoplasm
contain many cells in the growth fraction and usually grows at a more rapid rate
malignant neoplasms
exhibit local invasiveness or infiltration
malignant neoplasms
potential to spread to distant sites not
directly adjacent with the primary mass
metastasis
Enzymes produced by neoplastic cells that degrade adjacent tissues
- lysosomal hydrolases
- collagenase
- plasminogen activator
important factor in invasiveness
motility
Steps to complete metastasis
1) Release from site of origin
2) Transportation
3) Lodgment at distant site
4) Growth and survival at lodgment site
destroy vital structures due to their location and may even be fatal even if benign
tumor masses
wasting of body mass occurring out of proportion to the mass of neoplasm
cancer cachexia
Agents known to cause neoplasia
carcinogen
developmental process of neoplastic transformation occurring in cells
carcinogenesis
Classes of carcinogens
A. Direct-reacting carcinogens
B. Procarcinogen
C. Initiator
D. Promoter or co-carcinogen
E. Complete carcinogen
reactive substances that require no activation by biologic processes
Direct-reacting carcinogens
agents that must be metabolized in the animal body to the “proximate” or ultimate carcinogen
procarcinogen
may not be a carcinogen at all but are capable of initiating a change in the cell
initiator
agents that then applied after initiation
promotes the development of tumors
promoter or co-carcinogen
act as both initiator and promoter
complete carcinogen
Major Categories of Carcinogens
- Physical agents
- Oncogenic viruses
- Chemical carcinogens
Theories in Carcinogenesis
1) Somatic Mutation Theory
2) Epigenetic Theory
3) Oncogene Theory
Factors Influencing Carcinogenesis
- Host factors
- Environmental factors
occur on skin and may have a variety of forms from pedunculated to flat, smooth or villous
Papillomas
occur in glands
adenomas
smooth, spherical or membranous mass projecting on a mucosal surface;
maybe broad-based or pedunculated
polyp
common in the skin of dogs
hemangiomas
proper term for malignant tumor of lymphocytes
lymphosarcoma
clinical term for malignant cells circulating in the blood stream
leukemia
malignancy usually involving the granulocytic group, red cells, megakaryocytes
myelogenous leukemia
common descriptive term used for usually or greatly enlarged organ
abnormal mass
ulcerated lesion particularly on body
surfaces
persistent nonhealing ulcerating lesion
tumors that tend to be discrete masses
benign
not an indication of prognosis
Size
monotonous pattern of masses of cells with similar appearance and very little apparent stromal support
sheets of cells
cells forming acinar units, as in a secretory gland like the thyroid or mammary gland
acinar arrangements
endocrine tumors in which a clump of cells is surrounded by a narrowband of connective tissue stroma
nest of cells
cells line up in a picket fence-type arrangement
palisading or trabecular patterns
single, double or finger-like projection of tumor cells invade surrounding tissue
tubular arrangements
Terminologies for sarcomas
- Solid or loose arrangement
- Whorls
- Sheets
- Localized around blood vessels
- Spindly cells
- Fleshy cells
- Well or poorly-differentiated
- Monotonous
- Variable
prominent in many tumors, particularly in the center of a large mass
necrosis
Four main mechanisms for the spread of tumors
- By infiltration
- By spreading via blood vessels
- By spreading via the lymphatics
- By implantation
Two theories on the success of Metastasis
- The Soil Theory
- The Mechanical Theory
Treatment of Tumors
- by surgery
- by irradiation
- by chemotherapy
Methods of Tumor Diagnosis
- Histologic examinations
- Immunocytochemical examination
- DNA Probe analysis and DNA Flow Cytometry
- Tumor Marker Detection
most important method of tumor diagnosis
histologic examinations
detected in patients with hepatocellular carcinoma
alpha fetal globulin
abnormal antigen detected in blood of patient
with neoplastic condition
alpha fetal globulin
produced by fetal hepatocytes but normally disappears late in fetal life
alpha fetal globulin
widely used for cancer detection particularly in respiratory and gastrointestinal tumors
carcinoembryonic antigen
made by intestinal epithelium in fetal life and appear in adult life in events of
tumor
carcinoembryonic antigen
genes whose products are associated with
neoplastic transformation
oncogenes
normal cellular genes that affect growth and differentiation
Proto-oncogenes (Proto-oncs)
Proto-oncs can be converted into oncogenes by
- Transduction into retroviruses (v-oncs)
- Changes in situ that affect their expression and/or function, thereby converting them into c-oncs
viral oncogenes
v-oncs
cellular oncogenes
c-oncs
tumor must find a “suitable soil” for its growth
requirements
Soil theory
tumor will grow wherever it lands, and only mechanical factors and chance influence sites of metastases
Mechanical theory
When there is little apparent stroma, stromal arrangements may be described as:
- scant, as in sheets of cell
- Locular, as in the case of nests
- Scirrhous
testicular interstitial cell tumor kind of microscopic description
Palisading or trabecular patterns
Tubular arrangement tumor example
- basal cell tumors
- anal gland tumors
abnormal malignant cells present in the circulating blood, and it may occur in about half of the cases of lymphosarcoma
leukemia
common group of epithelial tumors in dogs
basal cell group
common group of epithelial tumors in dogs is the basal cell group examples
- sweat gland adenoma
- sebaceous gland adenoma
- hair follicle tumor
examples of polyp
- Nasal polyp
- Rectal polyp
warts or “kulugo”
papilloma
Host factors influencing Carcinogenesis
- age
- sex
- hormones
- nutrition
- breed
Neoantigens at the cell surfaces
tumor-specific transplantation antigens (TSTA)
TSTA’s share the same characteristics in cells induced by the same virus
virus-induced neoplasia
tumors produced by chemical carcinogens evoke transplantation immunity only against the same tumor
private antigens
prolonged exposure to sunlight predisposes to skin cancer in?
cats, cattle, humans
exposure of cattle to this plant may lead to bladder neoplasms
bracken fern
tumors which is common in male dogs than bitches
perianal gland tumor
tumors that are rare in male animals
mammary tumors
notoriously known for developing all sorts of
tumors
boxers
most commonly seen in German shepherd
hemangiosarcomas
Osteosarcomas are common in what breeds
- Great danes
- Saint bernard
- Irish wolfhound
