Neoplasia:
• state of excessive proliferation of cells
• No relation to normal growth and tissue repair.
• neoplasm or tumor=abnormal tissue mass
• rate of proliferation
– ranges from slightly above normal to
– wil
...
Neoplasia:
• state of excessive proliferation of cells
• No relation to normal growth and tissue repair.
• neoplasm or tumor=abnormal tissue mass
• rate of proliferation
– ranges from slightly above normal to
– wild uncontrolled growth
– extends and damages adjacent tissues.
– rarely exceeds the fastest normal rate of cell multiplication embryonic development, intestinal mucosal cells, blood and skin.
Neoplasia excludes abnormally rapidly cell growths
Metaplasia- change from a more specialized cell to a less specialized cell due to
• prolonged irritation or
• chronic infection eg
• columnal epithelium cell> more resistant squamous epithelium cells (proliferate very rapidly)
• fibroblasts into osteoblasts giving rise to new excessive bone growth
• Dysplasia:
disorganization of the pattern of squamous epithelium in tissues
e.g. skin, eosophagus and uterus
-due to chronic irritation or inflammation.
> increase in cell numbers, thickening of the epithelium. NB :metaplasias and dysplasias are usually reversible. may progress to neoplasias ( pre cancerous states).
e.g. chronic hypoxia > erythrocyte production and to a physiological polycythaemia, Parathyroid over activity > fibrous tumor –like growth of fibrous tissue in bones .
Broad classification of Neoplasms
(tumors):
2 Broad Classes
• Benign tumors
• Malignant tumors;
Both represent extremes of a spectrum of characteristics of tumor growth
– tumors of intermediate type occur combining the properties of both
– tumors may also slowly convert from one type to the other,
Benign tumor (simple tumor)
Characteristics
• usually have slow rate of growth which may cease
• Cells are well differentiated
• Cells resemble those of original tissue:
• edge of the tumor well defined
• Capsulated (pressure of surrounding react by forming a capsule around the tumor
• Clinical disorders from benign tumors normally arise from mechanical obstruction of viscera or pressure on nerves.
• Example of benign tumor is the uterine fibroid tumor which can be effectively removed by surgery,
• Any other examples???
• Malignant tumor – (commonly known as cancers or CAS)
– Are non encapsulated
– Edges are ill defined
– Cell are less differentiated than those of origin
– Have increased mitotic activity that may not be uniform and may have relapses
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