Neoplasia and Metaplasia Flashcards
what are Epithelial neoplasms?
derived from epithelia or glandular structures
what are Mesenchymal neoplasms?
derived from tissues descended from mesenchyme: muscle, fibroblasts, bone, cartilage, fat, etc.
what are Haemopoietic neoplasms?
derived from cells descended from the pluripotent bone marrow stem cell
what are Nervous system neoplasms?
derived from cells of the central and peripheral nervous system
what are Primitive embryonal neoplasms?
derived from immature cells
what are Germ cell neoplasms?
derived from germ cells in the ovary and testis
how does a tumour begin as the tumour parenchyma?
Clonal expansions of neoplastic cells
what are Supporting stroma composed of?
non neoplastic connective tissue, blood vessels and variable numbers of cells of the adaptive and innate immune system.
what is a desmoplasia?
Abundant collagenous stroma
such tumours will be rock hard or scirrhous.
Differentiation or anaplasia of malignant vs benign
BENIGN - Well differentiated; structure sometimes typical of tissue of origin
MALIGNANT - Some lack of differentiation (anaplasia); structure often atypical
Growth rate of malignant vs benign
BENIGN - Usually progressive and slow; may come to a standstill or regress; mitotic figures rare and normal.
MALIGNANT - Erratic, may be slow to rapid; mitotic figures may be numerous and abnormal.
Local invasion of benign vs malignant
BENIGN - Usually cohesive, expansile, well demarcated masses that do not invade or infiltrate surrounding normal tissues
MALIGNANT - Locally invasive, infiltrating surrounding tissue; sometimes may be misleadingly cohesive and
expansile
Metastasis of benign vs malignant
BENIGN - Absent
MALIGNANT - Frequent; more likely with large undifferentiated primary tumours
what is Metaplasia defined as?
the transformation of one differentiated cell type to another differentiated cell type;
often associated with tissue damage, repair, and regeneration.
AN example in the oesophagus?
gastroesophageal reflux damages the squamous epithelium of the oesophagus,
leading to its replacement by glandular (gastric or intestinal) epithelium more suited to an
acidic environment.
Barrett’s oesophagus
why is metaplasia reversible?
there is no intrinsic gene defect
Can metaplasia progress nto neoplasia
Metaplasia per se does not progress to neoplasia,
but because the metaplastic tissues are less genetically stable than their normal counterparts,
they are prone to undergo further transformation to dysplasia and neoplasia.
what does Dysplasia refers to?
a failure of normal maturation that occurs prior to the development of malignancy.
what is Dysplasia is often preceded by?
metaplasia
what is the main contrast from metaplasia?
it is usually irreversible.
where are Features of dysplasia are more easily recognised?
in epithelia than in mesenchymal or other tissues.
what is a carcinoma in situ?
When dysplastic changes involve the entire thickness of an epithelium,
the lesion is considered a preinvasive neoplasm and is referred to as carcinoma in situ.
Once the tumor cells breach the basement membrane, the tumor is said to be … ?
invasive.
what are the Morphological changes of dysplasia?
- Pleomorphism
- Abnormal nuclear morphology
- Abundant and/or atypical mitoses
- Loss of polarity
- Tumour giant cells
- Ischemic necrosis
how do Nearly all benign tumours grow?
Benign tumours grow and expand slowly,
as cohesive expansile masses that remain localised to their site of origin.
what is meant by a capsule?
they usually develop a rim of compressed fibrous tissue called a capsule that separates them from the host tissue.
what are Malignant neoplasms are typically?
invasive and infiltrative, destroying surrounding normal tissues.
Why is surgery difficult in malignant neoplasms?
They commonly lack a well defined capsule and cleavage plane, making simple excision impossible.
Surgery requires removal of a considerable margin of healthy and apparently uninvolved tissue.
what is Metastasis?
secondary growth of a neoplasm at one or more locations distant from the primary site .
what is the single most important feature distinguishing benign from malignant?
Metastasis