What is neoplasia?
the process of tumor formation
What are some disturbances of growth?
- Nonneoplastic disorders: developmental (congenital) defects, acquired defects
- Neoplastic disorders: aplasia, hypoplasia, miscellaneous developmental anomalies
What is aplasia?
A failure of primordium to grow but is usually accompanied by the presence of rudimentary organ. The term "aplasia" also is used to refer to the failure of a tissue to renew itself.
ex. Aplastic anemia refers to a failure of renewal of hematopoietic cells in the bone marrow.
What is agenesis?
A complete failure of the tissue to develop; no primordium.
What is primordium?
In embryology, is defined as an organ or tissue in its earliest recognizable stage of development.
What is hypoplasia?
- Failure of an organ to reach normal size.
- Occupies the spectrum between aplasia and normal development.
- ex. renal hypoplasia, testicular hypoplasia
What is the histological features of hypoplasia?
Presence of immature or "embryonic" tissue as a result of interruption in differentiation to normal mature cell types.
List some miscellaneous developmental anomalies.
- Failure to close or fuse-palatoschisis, interventricular septal defects of heartFailure to canalize or separate-atresia ani, horseshoe kidneyVestigial remnants-cystic rathke's pouch, brachial arches
- Accessory or supernumerary tissues-polydactyl
- Ectopic location of organ-ectopic thyroid, ectopic pancreas
- Abnormal overgrowth of tissue normal to the location in which they are found=hamartomas
- Normal tissue in an abnormal location= choristomas
List some acquired defects of cell growth.
- (cellular adaptation of growth and differentiation)
- atrophy=the partial or complete wasting away of a part of the body.
- hypertrophy=increase in the volume of an organ or tissue due to the enlargement of its component cells.
- hyperplasia=increased cell production in a normal tissue or organ. (increase in #)
- metaplasia=the reversible replacement of one differentiated cell type with another mature differentiated cell type.
- dysplasia=refers to an abnormality of development. Usually an expansion of immature cells with a corresponding decrease in the number and location of mature cells.
What is palatoschisis?
What is cheiloschisis?
What is atresia ani?
a congenital embryologic anomaly in which the hind gut fails to fully communicate with the perinium.
What is ectopic?
occurring in or an abnormal position or place; displaced.
What is ischemia?
restriction of blood supply to tissues causing a shortage of oxygen.
Decreased size of an organ or tissue after it has achieved normal size, caused by a loss of cells (necrosis) or decreased cell size.
Tissue/organ atrophy resulting from reduction in individual cells size is an ______________ response to altered demands on the cell, often a ______________ in __________________.
- work load
List some causes of cellular atrophy.
- Reduction in work load (disuse atrophy)
- Loss of innervation (denervation atrophy)
- Loss of hormonal stimulation
- Reduced blood supply
- Inadequate nutrition
- Aging (senile atrophy)
Increased size of an organ or tissue caused by increase in cell size, without cellular proliferation.
An increase in organ size or tissue mass caused by an increase in the number of constituent cells. Occurs only in cells capable of mitotic division (e.g. bone marrow, epithelia)
List some hyperplasia examples.
- Mammary gland hyperplasia
- Adrenocortical hyperplasia
- Compensatory hyperplasia of the contralateral kidney
- Regenerative hyperplasia of the liver or bone marrow
What are causes of endometrial hyperplasia?
- Progesterone in carnivores
- Estrogen in sows
What are causes of hyperplastic goiter (irregular enlargement of thyroid gland)?
What are causes of ceruminous gland hyperplasia?
What are causes of hyperplasia of bronchial epithelium?
PI3 and other viral infections
What are causes of hyperplasia of biliary epithelium?
Eimeria stiedae=a species of Eimeria that causes hepatic coccidiosis in rabbits.
What is nodular hyperplasia?
- Occurs commonly in the liver, pancreas and spleen of dogs and less commonly in cats.
- Consists of variably sized nodules of well-differentiated parenchymal cells within the tissue, similar to hepatomas or splenic lymphomas.
- Difficult to distinguish from neoplasia.
An adaptive response in which one type of mature differentiated cell is replaced by a different type that is not normal to that tissue or organ.
Does not occur as the result of alterations in existing mature cells, but rather it depends on proliferation of germinal, or stem cells whose progeny undergo modified differentiation.
Name some examples of Columnar to Squamous epithelial metaplasia.
- Respiratory tract in habitual cigarette smokers
- Respiratory tract after infections
- Excretory ducts of salivary glands, pancreas and bile ducts with stones
- Esophageal glands in vitamin A deficiency (avian).
Name some examples of Squamous to Columnar epithelial metaplasia.
The esophagus under influence of refluxed gastric acid, so-called Barrett esophagus.
Name some examples of fibrous tissues to Osseous or Cartilagenous metaplasia.
This change is less easily regarded as an adaptive response.
This term is used in 2 different contexts.
A generic term literally meaning "abnormal growth"-no implication of preneoplastic process.
A common but more restricted sense to describe a proliferative response accompanied by loss of regular differentiation and orderliness and by cellular atypia--it may be though of as disorderly or atypical hyperplasia and is regarded as a preneoplastic process.
By definition, dysplasia is a __________________ lesion and is irreversible if the cause is removed. Morphologically, difficult to distinguish a severely dysplastic lesion from a ____________ one. Severe dysplastic lesion is regarded as _____________.
What is the importance of dysplastic epithelial lesion?
- The increased risk of an invasive carcinoma developing at the site of the lesion or its cause is not removed. ex. carcinoma in situ