Pathology 1

• Cellular responses to stress and toxic insults include cellular adaptation, cell injury (reversible and irreversible), cell death (necrosis and apoptosis), intracellular accumulations, and pathologic calcification.
• Cellular adaptation is a physiological process that helps cells cope with stress and toxic insults.
• Cell injury can be reversible or irreversible, also known as cell death.
• Necrosis is a type of cell death that occurs due to the disruption of cellular homeostasis.
• Apoptosis is a type of programmed cell death that occurs in a controlled manner.
• Intracellular accumulations are conditions where substances accumulate inside cells.
• Pathologic calcification is a condition where calcifications form inside cells and tissues.
• Cellular responses to stress and toxic insults also include cellular adaptations, which are physiological changes that occur in response to stress and toxic insults.
• Hypertrophy is an increase in the size of cells, resulting in an increase in the size of the affected organ.
• Hyperplasia is an increase in the number of cells in an organ or tissue.
• Hyperparathyroidism is a condition where the parathyroid glands produce too much parathyroid hormone.
• Metastatic cancer to the bone is a condition where cancer has spread to the bone.
• Renal failure is a condition where the kidneys no longer function properly.
• Metastatic calcification is the precipitation of calcium phosphate in normal tissue due to hypercalcemia.
• Sarcoidosis is a condition where there are granulomas in the lungs and other organs.
• Paraneoplastic syndrome is a condition where there is a tumor in an organ and the symptoms are caused by the body's response to the tumor.
• Vitamin D intoxication is a condition where there is too much vitamin D in the body.
• Milk-alkali syndrome is a condition where there is too much calcium and potassium in the body.
• Parathyroid adenomas are benign tumors of the parathyroid glands.
• Paget disease is a condition where there are abnormalities in the bones.
• Multiple myeloma is a condition where there are abnormal plasma cells in the bone marrow.
• Atrophy is a reduction in the size of an organ or tissue due to a decrease in cell size and number.
• Metaplasia is a reversible change in which one differentiated cell type is replaced by another cell type.
• Large, homogeneous eosinophilic inclusions called Russell bodies are found in the cytoplasm of plasma cells.
• Accumulation of cytoskeletal proteins can lead to conditions like keratin filaments in alcoholic liver disease and neurofilaments in the neurofibrillary tangle found in the brain in Alzheimer disease.
• Protein reabsorption occurs in proximal renal tubules in patients with renal disease and proteinuria.
• Pathologic calcification can be of various types and is associated with conditions like Dystrophic calcification, Mönckeberg medial calcific sclerosis, and others.
• Defective intracellular transport and secretion of critical proteins can lead to conditions like α 1 - antitrypsin deficiency.
• Extracellular hyaline can be found in collagenous fibrous tissue in scar, hyaline change in uterine leiomyoma, hyaline membrane in newborn, hyaline arteriosclerosis, and hyalinization of glomeruli in chronic glomerulonephritis.
• Intracellular accumulations include Mallory bodies, Russell bodies (e.g. multiple myeloma), Crooke’s hyaline, Zenker’s hyaline change, and others.
• Abnormal or misfolded proteins may deposit in tissues and interfere with normal functions, a condition known as amyloidosis.
• Hyaline change refers to an alteration within cells or in the extracellular space that gives a homogeneous, glassy, pink appearance in routine histologic sections stained with hematoxylin and eosin.
• Exogenous pigments include Carbon, Tattoo, Lead, and Endogenous pigments include Lipofuscin (yellow-brown, finely granular cytoplasmic, often perinuclear), Melanin (brown-black), Hemosiderin (golden yellow to brown, granular or crystalline), Bilirubin, Anthracosis, Coal-worker pneumoconiosis, and others.
• Morphologic alterations in cell injury: Sequential development of biochemical and morphologic changes in cell injury, with potentially reversible damage, longer duration of injury leading to irreversible injury & cell death, and typically precedes ultrastructural, light microscopic & grossly visible morphologic changes.
• Reversible cell injury: cellular swelling (hydropic change/ vacuolar degeneration), plasma membrane alterations, mitochondrial changes, dilatation of endoplasmic reticulum (ER), nuclear alterations, failure of energy-dependent ion pumps in plasma membrane → cells incapable to maintain ionic and fluid homeostasis.
• Adaptive response in which one cell type that is sensitive to a particular stress is replaced by another cell type that is better able to withstand the adverse environment.
• Columnar to Squamous: respiratory tract in response to chronic irritation, stones in the excretory ducts of the salivary glands, pancreas, or bile ducts, vit A deficiency in respiratory epithelium, chronic irritation at endocervix.
• Causes of cell injury: two major classes of aetiologic factors: Intrinsic/ genetic derangements - developmental (deficiency of functional proteins), cytogenetic defects, Acquired - oxygen deprivation, trauma, radiation, chemicals & drugs, infectious agents, immunologic reactions, nutritional imbalances.
• Irreversible cell injury: necrosis, with increased eosinophilia, glassy homogenous appearance, vacuolated cytoplasm, nuclear changes (breakdown of DNA): karyolysis, pyknosis, karyorrhexis, discontinuities in plasma and organelle membranes, marked dilatation of mitochondria with the appearance of large amorphous densities, intracytoplasmic myelin figures.
• Squamous to columnar: Barretts oesophagus, left ventricular hypertrophy, prostate hyperplasia, Barretts oesophagus - metaplasia, endocervix - metaplasia, brain atrophy, skeletal muscle atrophy.