Disorders of Growth

1. Disorders of Growth Dr Eman MS Muhammad

2. Definition of growth: • Growth means increase in size and weight of the body or organ due to: • Increase in the number of constituent cells of the organ or • Increase in their size.

3. Factors controlling cellular growth and differentiation: • Factors that control growth and differentiation of cells are largely unknown. But factors affecting this growth can be considered under these headings:

4. Factors affecting this growth are: • Age:child grows rapidly before the age of 3 years, in adulthood the rate of growth is slow. • Type of tissue:thymus grows to the age of adult then stops or even regress, while sex organs grow very slowly before maturity then rapidly after puberty. • Type of cells:if they are labile, stable or permanent cells • Genetic factors:as affecting the tall of the persons

5. Nutritional state of the body: • Under nutrition →weakness • More nutrition →bad growth (obesity) • Hormones • Excess hormones (as growth hormones (Gigantism and acromegaly) • Deficient hormones as thyroid hormones (Cretinism and myxodema)

6. Presence or absence of disease: • In young age diabetes, thyrotoxicosis, T.B., anemia → under development • In adult chronic diseases as diabetes mellitus → weakness

7. Characters of physiological growth: • coordination • regular rate of growth • limited rate of growth • In reparative growth: • There is proliferation of cells to replace damaged cells.

8. Features: • It has a stimulus • It has a purpose • If the above features of physiological and reparative growth are not present → neoplasia results

9. Abnormalities of cellular growth

10. The abnormalities of these two functions are frequent and are considered under these headings: • Abnormalities of cellular growth that are either: • Excesses (hypertrophy and hyperplasia) or • Decreases which are either: • Developmental (agenesis, aplasia and hypoplasia). • Acquired after full development (atrophy)

11. 2. Abnormalities of cellular differentiation: It comprise metaplasia and dysplasia 3. Neoplasia: This is a completely abnormal cellular growth

12. Whereas hypertrophy stems from an increase in cell size, hyperplasia results from an increase in cell number

13. A: Hyperplasia: • Definition: • Hyperplasia/hypergenesis: Increase in size of an organ or tissue due to increase in number of its specialized constituent cells. • It results from cell proliferation. • It must be distinguished from enlargement due to edema, inflammation, amyloid infiltration and tumor formation.

14. Etiology: • It occurs as a result of a specific stimulus. • Persist only for so long as the stimulus is applied. • When the stimulus is removed the tissue tends to revert to its normal size. • Hyperplasia usually occurs due to increase in the functional demand or hormonal stimulation.

15. Microscopically, cells resemble normal cells but are increased in numbers. • Hyperplasia is different from hypertrophy in that the adaptive cell change in hypertrophy is an increase in cell size, whereas hyperplasia involves an increase in the numberof cells. • Hyperplasia, sometimes may result in gross enlargement of an organwhich is also an element of hypertrophy.

16. Hyperplasia differs from neoplasia in: • It usually occurs due to increase in the functional demand. • It occurs due to a specific stimulus. • It continues so long as the stimulus acts but stops when the stimulus stops and the tissue returnsto its normal size.

17. Significance: Hyperplasia is a common preneoplastic response to stimulus. • In hyperplasia, if the stimulus persists for long time it leads to tumor formation. • Neoplasia: In this type of growth, there is multiplication of cells but the organ has no ability to control its multiplication. • And if it is due to certain stimulus it continues after removal of the stimulus.

18. Types of hyperplasia: 1. Physiological hyperplasia: 2. Pathological a. Compensatory hyperplasia b. Hormonal hyperplasia c. Reparative hyperplasia d. Irritative hyperplasia

19. Physiological hyperplasia: • Occurs at puberty as in: • Breast:Hyperplasia of the epithelial tissue and surrounding specialized connective tissue of the female breast at puberty, during pregnancy, and lactation, and to a lesser extent towards the end of each menstrual cycle. • These changes are brought about by estrogens and progesterone.

20. Ovary and testes:The increase in size of the gonads and the secondary sexual organs is regarded as an example of physiological hyperplasia.

21. 2. Pathological hyperplasia: • Four types are known: A. Compensatory hyperplasia e.g. • Hyperplasia of bone marrow after hemorrhage or excessive hemolysis • Hyperplasia of the other testis after removal of one surgically (casterization)

22. B. Hormonal hyperplasia e.g. • Endometrial and breast hyperplasia as a result of estrogenic stimulation • Thyroid epithelial hyperplasia in response to excess thyrotrophic stimulation in thyrotoxicosis or as a result decreased iodine intake • Hyperplasia of the adrenal gland in Cushing’s syndrome or as a result of administration of adrenocortitrophic hormone

23. C. Reparative hyperplasia e.g. Formation of regeneration nodules in case of liver cirrhosis D. Irritative hyperplasia e.g. Hyperplasia of lymphoid tissue in infection and toxemia which is due to antigenic stimulation. Hyperplasia may be nodular or diffuse

24. B: Hypertrophy: • Definition: • It is an increase in the size of an organ or tissue due to increase in the size of its constituent specialized cells. • It is increase in the volume of an organ or tissue due to the enlargement of its component cells

25. It should be distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number. • Although hypertrophy and hyperplasia are two distinct processes, they frequently occur together, such as in the case of the hormonally-induced proliferation and enlargement of the cells of the uterus during pregnancy.

26. Pure hypertrophy without accompanying hyperplasia occurs only in the muscles. • The stimulus is always a mechanical. • It occurs in permanent cells which cannot divide to compensate for excessive work or functional demand.

27. Etiology: • increased work • increased hormone

28. Types of hypertrophy: 1. Physiological hypertrophy 2. Pathological hypertrophy a. Adaptive hypertrophy b. Compensatory

29. 1. Physiological hypertrophy: as in: • Uterus:in pregnancy there is an increased rate of hypertrophy which is partly mechanical and partly hormonal due to o estrogen effect. • Skeletal muscle:In muscles of the athlete due to the mechanical affect.

30. 2. Pathological hypertrophy A. Adaptive hypertrophy: I. Cardiac muscle: a. Left ventricle: • Aortic valve diseases (stenosis and regurgitation) • Mitral incompetence • Systemic hypertension • Severe anemia • Thyrotoxcosis

31. b. Right ventricle: • Chronic pulmonary diseases → cor- pulmonale • Mitral stenosis • Pulmonary stenosis and regurgitation • Congenital left to right shunt as A.S.D, V.S.D, P.D.A

32. II. Smooth muscles: • Hypertrophy in a hollow muscular organ proximal to obstruction or stricture. a- Alimentary tract: Esophagus:in cases of. • Post inflammatory stricture, achalasia of the cardia, carcinoma

33. Stomach: in cases of: • Idiopathic hypertrophic pyloric stenosis. • Pyloric stenosis due to peptic ulcer or carcinoma. Intestine: in cases of: • Stricture following T.B enteritis. • Proximal to annular stricture of the colon in cases of carcinoma

34. b- Urinary bladder: • Prostatic enlargement due to urothelial stricture c- Arteries:in • Muscular arteries due to hypertension • In segments of veins used to replace arteries surgically

35. B. Compensatory: • Occurs in paired organs when one of the two is pathologically destroyed or surgically removed. • e.g. after nepherectomy, the other kidney enlarges in size due to hypertrophy of the glomeruli and tubules.

36. C: Agenesis: • Complete failure of development of a part or organ which is therefore absent – e.g. kidney.

37. D: Aplasia • It means complete failure of development of the organ, which becomes rudimentary (stop development) e.g. kidney.

38. E: Hypoplasia: • There is failure of development to a full mature size. e.g. hypoplasic kidney is represented by only a fibrous nodule. • Also testis that fails to mature at puberty is termed hypoplastic. So hypoplasia may become evident during childhood.

39. F: Atrophy: • Is the acquired decrease in size of a part or organ due to diminution in the number or size of its constituent cells or both which is common. • In muscles it is a decrease only in size of its cells.

40. In atrophy the cells show abundant secretorylysosomes (autophagocytic vacuoles) and some residual bodies. Also apoptotic bodies are often seen. • Atrophic cells are usually replaced by fibrous tissue, rarely by fatty tissue in skeletal muscles and pancreas.

41. Types of atrophy: A. Physiological atrophy • Generalized • Localized B. Pathological atrophy • Generalized • Localized

42. A. Physiological atrophy: • The term “involution” is used synonymously with physiological atrophy. • Two categories are known: • Generalized atrophy: • Senile atrophy: cells ↓ in length and weight after the age of 50-60 in males and after menopause in females. • Localized atrophy:

43. It is considered in 3 age groups: • In the fetus: Branchial cleft, notochord, thyroglossal duct are good examples. • In infancy:The ductusarterioses and umbilical vessels either disappear or remain as fibrous cords.

44. Later life: The lymphoid tissue specially thymus after the age of puberty. • The breast and gonads after menopause.

45. B. Pathological atrophy: • This may be generalized or localized. • Generalized atrophy: • Starvation atrophy • Senile atrophy • Endocrine atrophy

46. 1. Starvation atrophy: in cases of prolonged starvation and chronic malnutrition • Chronic debilitating diseases as the rate of catabolism is more than the rate of anabolism in cases of: T.B, diabetes mellitus, thyrotoxicosis, addison’s disease • Some mental diseases due to ↓ food intake • Cachexia of malignant diseases

47. N.B. In extreme starvation the heart may be reduced in size, the epicardial fat is replaced by pale translucent material “serous atrophy”, and the vessels are tortuous. • Lipofuscin accumulate in the cardiac muscle fibers leads to brown color “brown atrophy of the heart”.

48. 2. Senile Atrophy: • It is marked accentuation of the process of physiological atrophy. 3. Endocrine atrophy: • Hypopitutarism leads to atrophy of thyroid, adrenal cortex, gonads. • The whole body may become stunted.

49. Characters of generalized atrophy: • Skin: Wrinkled due to loss of subcutaneous fat which in replaced by hyaline material, the skin become en-elastic and thin. • Bones: Are rarified and easily fractures due to decalcification and osteoporosis. • Visceral organs: Brown atrophy of the heart and sometimes brain atrophy.

50. Localized atrophy: • Ischemic atrophy • Pressure atrophy • Disuse atrophy • Neuropathic atrophy • Hormonal atrophy • Idiopathic atrophy