General Pathology PDF

Dr. Mohammed Abdellah General Pathology sinaiuniversity.ne t  Cell injury NECROSIS & Apoptosis By the end of lecture:you should be able to: --Understand reversible and irreversible cell injury -inttracellular accumulations andextracellular deposits; Amyloidosis Understan...

Dr. Mohammed Abdellah General Pathology sinaiuniversity.ne t  Cell injury NECROSIS & Apoptosis By the end of lecture:you should be able to: --Understand reversible and irreversible cell injury -inttracellular accumulations andextracellular deposits; Amyloidosis Understand apoptosis Understand Necrosis, definition and types….  Reversible and Irreversible Cell Injury (Degeneration and Necrosis) Definition: Degeneration (Reversible cell injury) means morphologic and metabolic changes in living cells resulting from non fatal injury. These changes occur in the cytoplasm while the nucleus remains within normal. Pathogenesis : Mitochondrial theory of degeneration. Cloudy swelling = Albuminous Degeneration Hydropic Degeneration Definition: Cellular degeneration characterized by intracellular accumulation of water. Fatty change = Fatty degeneration = Steatosis Definition : Pathological accumulation of neutral fat in different organ and parenchymatous cells.  Intracellular Accumulations and Extracellular Depositions A-Fats: Accumulation of cholestrol in wall of blood vessels in atherosclerosis. B- Mucin : (Mucoid degeneration): Abnormal accumulation of mucin inside epithelial cells. C-Glycogen: Glycogen storage diseases are caused by enzymatic defects. D- Proteins: -Hyaline change = HyalinosisIt is a change in cells or tissues which appear homogenous, glassy, pale pink when stained with H & E. Types and causes: 1- Extracellular hyalinosis: Old scars and keloids. 2- Intracellular hyalinosis: Mallory body : in liver cells of alcholics.  Amyloid deposition (Amyloidosis) It is the pathological deposition of pale, pink, homogenous, refractile, structureless protein material. It is deposited in various tissues, mainly extracellularly in the wall of blood vessels and in the basement membrane. Staining of amyloid material: 1-Gross staining Dark red with Lugol’s iodine that is transformed into dark blue or black after the addition of diluted sulphuric acid. 2-Microscopic staining: Pale pink with H & E stain. With congo red stain, the amyloid shows apple green birefrengence when observed by the polarizing light  Amyloid deposition (Amyloidosis) Types and classification of Amyloidosis A-Systemic (generalized) Amyloidosis: 1-Immunocyte dyscrasias with amyloidosis (primary amyloidosis) 2-Reactive systemic amyloidosis (secondary amyloidosis) 3-Hemodialysis associated amyloidosis 4-Hereditary amyloidosis B- Localized amyloidosis: Senile cardiac or senile cerebral amyloidosis. Tumors of endocrine glands with amyloid deposits such as medullary carcinoma of thyroid. Idiopathic localized amyloid deposits.  Apoptosis A distinctive type of cell death which usually involves single cells or clusters of cells, without an inflammatory reaction in the surrounding tissues. It is thought to be responsible for cell turnover and for programmed cell destruction. It is also called cell suicide. Pathological features: Cells appear rounded with eosinophilic cytoplasm. DNA damage and chromatin fragmentation. Formation of membrane blebs and apoptotic bodies. Examples: Focal elimination of cells during embryonic development. Liver cells in viral hepatitis. Cell injury caused by cytotoxic T-lymphocytes. Endometrium during the menstrual cycle Apoptosis of liver cells  Necrosis  NECROSIS Definition: Local death of tissue or group of cells in the living body. It may occur directly or follow severe degeneration. Causes: different causes of cell injury mainly ischaemia. Gross: Necrotic area is opaque & yellowish and surrounded by a zone of hyperaemia. Micro: 1-Nuclear changes : Pyknosis, Karyorrhexis and Karyolysis 2-Cytoplasmic changes : The cells are swollen (cytomegaly). The cell membrane is lost & the affected cells appear as structureless pink mass (ghost cells) in which the general features may be preserved while the cellular details are lost.  Types of Necrosis 1-Coagulative necrosis: Usually caused by ischaemia and the necrotic tissues are opaque and firm due to coagulation of cellular proteins. The necrotic area is called infarction. 2-Liquifactive necrosis: Necrotic tissue is soft and rapidly liquifies, It is seen in brain infarction and pyogenic abscess. 3-Caseation necrosis: Type of allergic coagulative necrosis followed by slow partial liquefaction. The tissues are dry, pale yellow & cheesy. It is due to delayed hypersensitivity reactions specially in tuberculosis. 4-Fat necrosis: of two types Enzymatic fat necrosis: in casesof acute haemorrhagic pancreatitis. Traumatic fat necrosis: in cases of trauma to the female breast or subcutaneous fat.  NECROSIS renal infraction Splenic ifarcion  NECROSIS Brain liquifactive ncrosis Liquifactive necrosis (liver abscess  Pathological Calcification 1- Dystrophic calcification More common. Deposition of calcium salts in degenerated & necrotic tissues. Blood calcium level is normal. Cause is relative alkalinity or increased phosphatase activity in these tissues. Sites: Areas of degeneration: Atherosclerosis and Hyalinosis Areas of necrosis : Thrombosis, Tuberculosis, Fat necrosis. 2- Metastatic calcification Less common. Deposition of calcium salts in living tissues. Blood calcium level is elevated. Cause is increased calcium absorption, increased calcium mobilization from bone, hyperparathyrodisim, hypervitaminosis D, bone metastases or chronic renal failure. Sites: Renal tubules, wall of stomach, lung alveoli and walls of blood vessels. Thanks