Pathology - Abnormal Cell Growth.pdf

8/20/2019 Pathology - Abnormal Cell Growth.pdf

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NORMAL CELL GROWTH

Cell development division

differentiation

maturation

Cell proliferation and cell death

Growth and differentiation

controlled to maintain normal structure of a

particular tissue

Growth of tissue

reflects net balance of cell proliferation and cell

differentiation


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Cytokines: – Cyclin-dependent kinases (CDKs)

Growth factors: – PDGF, FGF

Growth Inhibitors

Cancer suppressor genes: – p53

Oncogenes: – c-onc, p-onc, v-onc

CONTROLS OF GROWTH


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Development of different blood cells from hematopoietic stem cells to mature cells.


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ABNORMAL CELL GROWTH

Interruption in one of the growth process

Result in either a decrease or increase in the tissue

mass

Change in the morphological features

Disrupt the function of the cells


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• ATROPHY

• HYPERTROPHY

•

HYPERPLASIA

•

METAPLASIA• DYSPLASIA

• NEOPLASIA

Cell size and

number

Cell type,shape and

organization

CHANGES IN CELL


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CHANGES IN CELL


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ATROPHY

Decrease in the cell size

reduced amount of cytoplasm

reduced number of cytoplasmic organelles

reduced metabolism

• Degenerating organelles

- taken up in lysosomal vacoules for enzymatic degradation


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ATROPHY

Decrease in the number

imbalance of cell proliferation

cell death

over a long period

Partial or complete wasting part of the body

Reversible process


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Mutation

– Destroyed gene that build up the organ

Poor nourishment

Poor circulation

Loss of hormonal support

Loss of nerve supply to the target organ

Disuse or lack of exercise to the tissue involved

Causes of ATROPHY


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Physiological ATROPHY

Part of normal development

Reabsorption and breakdown of tissues

Apoptosis on a cellular level

Examples:

– shrinking and involution of the thymus in early childhood

– shrinking and involution of the tonsils in adolescence


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Occurs as a result of disease

Loss of trophic support

– due to other disease

Example:

– muscle wasting in prolonged bedrest

Pathological ATROPHY


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Muscles atrophy


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HYPERTROPHY

Increased size of individual cells

Due to:

Increased amount of cytoplasm

Increased number of cytoplasmic organelles

Increase in size of tissue

Reversible or irreversible process


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Adaptative mechanism

Due to increased demand in the body

Reversible

– tissues revert to normal when the demand is removed

Example:

– cardiac hypertrophy during exercise

Physiological HYPERTROPHY


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Irreversible

Absence of appropriate stimulus of increased

functional demand

Associated with:

- fibrosis

- cardiac dysfunction

Pathological HYPERTROPHY


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Normal organization of cardiac structure and normal or slightly enhanced cardiac function


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HYPERPLASIA

Stimulated cells of the tissue

Cells undergo mitotic division

Increased number of the cells

Increased in the size of the tissue

Microscopically cells resemble normal cells

Common preneoplastic response to stimulus

Stimulus: hormone of the affected organ


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Increased demand

Chronic inflammatory response

Hormonal dysfunctions

Compensation for damage or disease elsewhere

Causes of HYPERPLASIA


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Normal condition

Eg: Response to pregnancy

– growth and multiplication of milk-secreting glandularcells in the breast

– prepare for future breast feeding

Eg: Obesity

– Increase in size and number of adipocytes

Physiological HYPERPLASIA


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Excess stimulus

Example : Bilateral adrenal hyperplasia

– due to excessive secretion of ACTH to the adrenal gland

– Cushing’s disease

Pathological HYPERPLASIA


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Normal (top) and hemorrhagic (bottom)

adrenal glands

Adrenal glands in situ


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Non-Neoplastic Proliferation

* • Atrophy & Hypertrophy – Size

• Hyperplasia – Number

• Metaplasia – Change

• Dysplasia – Disordered


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Abnormal growth involving

differentiation

• Metaplasia

– Abnormal differentiation of stem cell

– One type of mature cell replace by adifferent type of mature cell

– Reversible

– Regular organization of tissue


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Abnormal growth involving

differentiation

• Dysplasia

– Abnormal differentiation and maturation

– Loss control of organization

– Slight increase in cell number

– Partial reversible

– Premalignant lesion

• Neoplasia


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Thank you for your attention!

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Pathology - Abnormal Cell Growth.pdf