Cellular Pathology - Growth Adaptation

I. Growth Adaptation

Growth adaptation의 종류

II. Hyperplasia & Hypertrophy

■  Hyperplasia

- increase number of cells

- production of new cells from stem cells

■ Hypertrophy

- increase the size

■ Clinical point

- Uterus during pregancy : Hyperplasia + Hypertrophy

- Cardiac muscle, skeletal muscle and nerve : only hypertrophy

- Endometrial hyperplasia : can progress to dysplasia and cancer

- BPH : not risk for prostate cancer

III. Atrophy 

- cells number and size decrease

- by. Ubiquitin-Proteosome degradation & autophagy of cellular component

IV. Metaplasia

- change to cell type

- m/c) surface epithelium change (squamous or columnar)

- by reprogramming of stem cells

- in theory, it is reversible

- under persistent stress, metaplasia can change to dysplasia or cancer
■ Clinical point

- Barrett esophagus : nonkeratinizing squamous epithelium to mucin producing columnar cells 

- Apocrine metaplasia of breast : no increased cancer (exception)

- Keratomalacia (Vit-A deficiency) : thin squamous epithelial to stratified keratinizing squamous epithelium 

- Myositis ossificans : after trauma muscle change to bone 

V. Dysplasia

- disordered cellular growth 

- in theory, Dysplasia is reversible

■ Clinical point

- Precancerous cell : e.g. CIN 

VI. Aplasia and Hypoplasia

- Aplasia : failure of cell production during embryogenesis (e.g. unilateral renel agenesis)

- Hypoplasia : decrease cell production in embryogenesis result in small organ (e.g. steak ovary in 45.XO)