cell injury revision notes pathhology

1. Pathology

2. Causes of Cell injury
• Hypoxia
• Most common cause of cell injury
• Ischemia  mc cause of hypoxia
• Physical agents
• Chemical agents
• Infections
• Immunological agents
• Genetic cause
• Nutritional imbalance

3. Hypoxia
• Neurons
• Most susceptible tissue to ischemia
• Irreversible damage with in 3 to 4 minutes
• Myocardial cells
• Irreversible damage with in 20 to 30 minutes
• Fibroblast
• Most resistant to ischemic damage

8. Cellular adaptive response to injury
• Atrophy
• Hypertrophy
• Hyperplasia
• Atrophy
• Metaplasia
• Dysplasia

9. Hyperplasia
• Increase in number of cells
• Hyperplasia is absent in heart brain & skeletal muscle
• Physiologic
• Compensatory : after hepatectomy
• Hormonal : breast @ puberty
• Antigenic stimulation : lymphoid hyperplasia
• Pathologic
• Mediated by GF cytokines / increased expression of proto-
oncogenesincreased DNA synthesis & cell division

10. Hypertrophy
• Increase in size of cells in nondividing cells
• d/t induction of genes  increased transcription /GF/vasoactive agents
increased syn of intracellular components
• Increased mechanical demand
• Physiological
• Skeletal muscle
• Pathological
• Increased endocrine stimulation
• Lactating breast

11. • Hyperplasia & hypertrophy occur together
• in gravid uterus
• Mainly hypertrophy + only some hyperplasia
• In breast during puberta period & pregnancy

12. Atrophy
• Decrease in cell size & functional ability
• Causes
• Decreased work load/disuse
• Loss of blood / nerve /hormonal stimulation
• Malnutrition
• Ageing
• Pressure
• Small shrunken cells with lipfuchsin granules  brown atrophy
• DECREASED PROTEIN SYNTHEISS
• Increased protein degradation
• In lysosomes
• Ubiquitin –proteasome pathway
• Autophagic vacuoles d/t decreased nutrition

14. Metaplasia
• Reversible change of one cell
type by another in response to
irritation
• d/t tissue specific &
differentiation genes 
reprogramming of stem cells
• Squamous metaplasia
• In respiratory epithelium in smokers
• Columnar metaplasia
• In baretts esophagus

15. • Vitamin A deficiency or excess metaplasia
• Deficiency  squamous metaplasia in respiratory epithelium

16. Baretts esophagus
• Intestinal metaplasia (d/t presence
of goblet cells )
• Increased risk of endometrial
adenocarcinoma

17. DysplasiaNOT A CELLULAR ADAPTATION
• An abnormal proliferation of
cells
• Increase in size shape & loss of
cellular organisation
• Intact basement membrane
• Not malignancy but nay progess to
malignancy

19. Mechanism of cell injury

22. Effect of influx of Ca2+

23. Increased cell
membrane
permeability

24. Mitochondrial
dysfunction

26. Features of reversible injury
• Cellular swelling
• First manifestation of all cell injury
• Except for apoptosis in which cell shrinkage is seen
• Hydropic degeration /cloudy swelling
• Intacellular water accumulation

29. Mechanism of
reversible cell injury

31. Hypoxia  earliest involvement of mitochondria
 inhibit oxidative phosphorylation

32. Myelin figures are seen in cell inury
• Whorls of laminates PL & Ca2+
• More promineny in necrosis than in
reversible cell injury
• Break down of membrane organelles
 composed of phospholipids

33. Light microscopic changes in reversible injury
• Irregular swelling /cloudy
swelling/hydropic change
• Prominent in kidney
• Earliest
• Fatty changes
• In cells involved in fat metabolism
• In hepatocytes & myocardial cells

34. Irreversible cell injury
• Severe membrane damage
• Masive influx of ca2+
• Efflux of intracellular enzymes in to circulation
• Marked mitochondrial dysfunction

38. • CELLS MOST SENSITIVE TO HYPOXIA  NEURONS
• ESP PYRAMIDAL CELLS IN HIPPOCAMPUS

39. Stepladder pattern d/t endonuclease
induced internucleosomal damage in
apoptosis
Diffuse smearing in necrosis

40. Cytoplasmic changes in necrosis
• Increased eosinophilia
• d/t protein denaturation
• Glassy appearance d/t loss of glycogen
• Cytoplasm is vacuolated  moth eaten
• D/T ENZYMATIC DIGESTION  VACOULE APPEAR
• Finally calcification

41. Nuclear changes in necrosis

42. Nuclear changes in necrosis
• Pyknosis
• Nuclear shrinkage
• Chromatin condensation
• Karyorhexis
• Nuclear fragmentation
• Karyolysis
• Decrease basinophilia
• d/t dissolution of chromatin

43. Types of necrosis
• Coagulative
• Liquefactive
• Caseous
• Fat
• Fibrinoid necrosis
• Gangrenous necrosis

44. Coagulative necrosis
• Most common type
• Architecture of tissue preserved
• Ghost cell outline /tomb stone
• Cellular outline is maintained
• Loss of nucleus
• a/w ischemia (hypoxia)
• d/t denaturation of protein
• Seen in all tissues (heart***(mc) liver kidney)
• except brain LIQUEFACTIVE
• Zenkers degeration necrosis
• Waxy hyaline degenerstion of skeletal muscle in a/c infectious ds

45. Liquefactive necrosis
• Seen in
• focal bacterial
• Most common cause
• ischemia in brain
• d/t local stromal support & abundant liquefactive necrosis
• occasionally fungal infections
• d/t enzymatic degradation
• Inflammatory cells –> hydrolytic enzymes  tissue degradation into liquid
viscuous mass  no cellular details

46. Caseous necrosis
• Combination of liquefactive & coagulative
necrosis
• d/t mycolic acid of TB
• Friable cottage cheese like reaction
• Characteristic feature of TB
• Unlike coagulative necrosis
• Tissue architecture is completely obliterated

48. • If caseation is absent & lymphoid infiltrate is absent
• In naked granuloma  sarcoidosis

49. Fat necrosis
• d/t lipases on fatty tissue
• Seen in breast omentum pancreatitis
• Chalky white in appearance

50. Fibrinoid necrosis
• Immune reactions involving blood
vessels
• Complexes of Ag & Ab around blood vessel
with leakage of fibrinogen
•  bright pink amorphous densities
• Seen in
• PAN
• Malignant hypertension
• Immune complex vasculitis

51. Fibrinoid necrosis is seen in

52. Gangrenous necrosis
• Dry gangrene
• Microscopic pattern of coagualative
• POVD
• wet gangrene
• Microscopic pattern of liquefactive necrosis
• Superadded putrefaction
• Bowel mouth vulva cervix
• Gas gangrene
• Cl perfringens
• P/S  poikilocytoses(spherocytes)

53. Necrosis vs apoptosis

55. Necrosis Apoptosis
Increase in cell size Decrease in cell size
Pyknosis karyorrhexis karyolysis Nuclesome
Membrane damage Intact membrane

56. Apoptosis
• Active process (energy dependent process d/t involvement of
mitochondria)
• Programmed cell death

57. Physiological
• Embryogenesis organogenesis
neovascularisation
• Hormone dependent involution
of tissues
• Cell death after completion of its
function
Pathological
• Accumaltion of misfolded
protein
• Duct obstruction
• Cytotoxic CTx / Rtx

58. Morphological features
Most characteristic feature
Earliest feature

59. Chromatin condensation

60. Biochemical features of apoptosis
• Protein cleavage by caspases
• DNA break down by endonuclease
• 50 – 300 kbp size step ladder pattern in agarose gel electrophoresis

61. Caspases
• Proteases with cysteine group

62. Annexin V is a marker of apoptosis
• Flipping of phosphatidyl serine from inside to outside allow
recognition of apoptotic cells

64. Regulation of apoptosis
• Bcl-2
• Located on mitochondrial membrane
• Inhibit apoptosis
• Bcl – xL  lower apoptosis
• Bak bax bim
• Stimulate apoptosis
• Bcl – Xs (S- stimulate apoptosis )

69. Mechanism of apoptosis
• Initiation
• Activate initiator caspases
• 2 pathways
• Intrinsic (mitochondrial)
• Extrinsic (death receptor pathway)
• Execution
• Activate caspase 3 *** /6/7 (executioner caspases )

70. • Glucocorticoids  stimulate apoptosis
• Hence used in Rx of leukemia /lymphoma/myeloma
• Sex steroids inhibit apoptosis

73. Intrinsic pathway
Wheel like hexamer (apoptosome)
activation of caspase 9

75. Smac &
diablo are
proaptotic

76. Extrinsic pathway
• TRAIL
• TNF related apoptosis inducing
ligand binds to DR4 & 5
Caspase 10 in humans

79. FLIP inhibits
extrinsic
pathway

80. CD 95
CD 95
is molecular marker of apoptosis

84. Diagnosis of apoptosis
• 1. Chromatin condensation seen by hematoxylin, Feulgen and
acridine orange staining.
• 2.Estimation of cytochrome ‘c’
• 3. Estimation of activated caspase
• Caged flurophores , FRET
• 4. Estimation of Annexin V
• 5. DNA breakdown at specifc sites can be detected by ‘step ladder
pattern’ on gel electrophoresis or
• 6.TUNEL (TdT mediated d-UTP Nick End Labelling) technique.
• Terminal transferase

86. Necroptosis
• Hybrid of necrosis + apoptosis
• Programmed cell death with out caspase activation
• Cell swelling
• Increased lysosomal permeability
• Cell membrane damage
• Presence of inflammation

87. Pyroptosis
• Neither necrosis nor apoptosis
• Caspase dependent (caspase 1 & 11 ) programmed cell death
• Cell swelling
• Cell membrane damage
• Presence of inflammation
• Caspase 1 & caspase 11 involved

88. Free radical
• Single unpaired electron in outer orbit
• Reactive oxygen species
• Normally produced as an unavoidable by product of mitochondrial respiration

93. Free radical injury

95. Fenton reaction Fe2+ is converted to Fe3+

96. Subcellular response to injury
• Autophagocytosis
• Lysosomal digestion of cells own components
• Digest protein CHO except lipids
• Cell eats its own components
• In nutrient deprivation
• In atrophy
• Autophagosome +
• Autophagolysosome+

97. Deletion of Atg5 increased susceptibility to
tuberculosis
• Atg5 autophagy related genes

99. Heterophagy
• Cells ingest substances from outside for intracellular digestion
• Induction of SERhypertrophy of SER
• On phenobarbitone therapy  hypertrophy of SER

100. Ischemia reperfusion injury
• In cerebral/myocardial ischemia
• Recruitment of WBC  inflammation + generation of free radicals

101. Reperfusion injury
• Appears as contraction bands after MI

102. Intracellular accumalations

103. Lipids
• Intracellular lipid accumulation  steatosis
• Mainly in liver
• Triglyceride ***(mc)
• Cholestrol &CE
• PL
• Tigeroid / tabby cat myocardial cells
• Alternating bands of dark red normal myocardium with yellow streaks
• d/t lipid accumaltion
• Special stains
• Oil red O stain
• Sudan black B
• Sudan IV
• Osmium tetroxide

104. Proteins
• In proteinuria Protein accumalates in proximal renal tubule
• Russel bodies
• Intracytoplasmic accumaltion of Ig
• Defective protein folding  accumulation
• Alzheimers d/s /parkinsons ds/huntingtons ds
Russel bodies

105. Chaperones
• Chaperones in the ER control proper
folding of newly synthesised proteins

108. Pigments
• Exogenous
• Tattooing with india ink /cinnbar
• Carbon in lungs
• Endogenous
• Lipofuschin
• Melanin
• Haemosiderin

109. Lipofuschin pigment
• Wear & tear pigment
• Telltale sign of free radical injury
• From indigested material from radical mediated lipid
peroxidation
• Perinuclear brown pigment
• Composed of lipids & PL in combn with proteins
• Cellular atrophy
• Brown atrophy of myocardium

111. Melanin
• Only endogenous brown black pigment
• In melanocytes & substantia nigra
• Detected by fontanna masson staining

112. Hemosiderin
• Golden yellow brown pigment
• Granular intracellular pigment composed
of aggregated ferritin micelles
• In areas of haemorrhages & bruises /
systemic iron overload
• Detected by perl’s Prussian blue
reaction

113. Prussian blue

114. Pathologic calcification
• Abnormal deposition of Ca2+ along with small amounts of mg2+ & fe2+
• Starts
• In mitochondria or microsomal vesicles
• In basement mebrane in kidney
• Stains for Ca2+
• VON – KOSSA (BEST)
• ALIZARIN RED-S
• Calcein stain
• Tetracycline labelling index (best method to detect bone demineralisation)
• 2 types
• Dystrophic
• Metastatic

115. Dystrophic
• Dead / degenerated tissue
• Serum Ca2+ is normal
• Psammoma bodies
• In meningioma/papillary CA thyroid/mesothelioma/serous cystadenoma of ovary
• Monckebergs medial calcific stenosis
• Tuberculous LN (caseous necrosis)
• Atherosclerosis
• Fat necrosis

116. Metastatic
• Raised Ca2+  calcification in normal tissues
• Causes
• Hyperparathyroidism ***
• **Parathyroid adenoma ***
• Vitamin A toxicity
• Vitamin A activates osteoclast  increased bone resorption & hypercalcemia
• Milk alkali syndrome
• Renal failure
• Vitamin D related disorders
• Vitamin D intoxication
• Williams syndrome (idiopathic hypercalcemia of infancy)
• Sarcoidosis
• Saracoid gramuloma synthesise excess 1,25 OH vitamin D3

117. Metastatic calcification
• Most coomon site
• Lung alveoli
• Systemic arteries & pulmonary V
• Gastric mucosa
• Cornea & conjunctiva

118. Glycogen storage ds
• Best carmine or PAS with diastase sensitivity
• Best fixative is alcohol

119. Hyaline change
• Pink homogeneous appearance
• Intracellular
• Mallory alcoholic hyaline
• Russel bodies
• Zenkers degeneration
• Extracellular
• Hyaline memb in newborn
• Corpora amylacea in brain prostate
• Hyaline arteriosclerosis

120. Cellular aging
• Most widely used theory
• Free radical mediated damage

121. Telomeres
• Short stretches of DNA @ end of chromosomes
• Important in ensuring complete replication of chromosomes & protects
chromosomal ends from fusion & degradation

122. Telomerase shortening
• Progressive telomerase shortening  limit cell division to 60 to 70
times  cellular senescence

123. Telomerase
• Aare reverse transcriptases or RNA dependent polymerase
• Normally present in germ cells >> stem cells
• Presence in normal somatic cells  neoplastic transformation

126. WERNER SYNDROME
• A defect in DNA helicase enzyme
• required for DNA replication and repair results in premature ageing

127. sirtuin
• Plays an important role in aging / DM & various cancers
• NAD dependant deacetylase
• Stimulates protein folding
• Decrease apoptosis
• Inhibit free radical damage
• Increase insulin sensitivity

130. • Commonest fixative
• In light microscopy 10 % bufferd formalin
• In e microscopy  glutaraldehyde

132. megamitochondria
• ALD
• Steatohepatitits
• Mitochondrial myopathies
• oncocytoma

133. Zenkers degeneration
• True coagulative necrosis
• Affecting skeletal muscles
>>> cardiac muscles
• Rectus diaphragm
• During a/c infections
typhoid

134. Oncocytes
• Epithelial cells stuffed with
mitochondria  imparts granular
appearance to cytoplasm
• Granular pinkish
• Abundant megamitochondria
• Seen in
• Thyroid
• Hurtle cells
• Parathyroid
• Lung & pituitary
• pancreas
• Salivary gland
• Kidney

135. Oncocytoma
• Benign tumr with oncocytic cells
• In thyroid kidney & salivary gland
• Renal oncocytoma
• Mahagoni brown colour with central scar

136. Councilman bodies Hepatitis
Gamna gandy bodies Congestive splenomegaly calcific deposits admixed with
haemosiderin on fibrous tissue
Negri bodies Rabies Negri bodies are distributed
throughout the brain, particularly
• Most commonly in
hippocampus
• in Ammon's horn, the cerebral
cortex, the brainstem, the
hypothalamus, the Purkinje cells
of the cerebellum, and the
dorsal spinal ganglia
Lewy body Parkinsons disease
Hirano bodies Alzheimers ds
Asteroid bodies Sarcoidosis
Aschoff bodies Rheumatic heart ds
Verocay bodies Schwannoma
Cal exner bodies Granulosa

137. Cytoskeleton
• Actin
• Thinnest
• Intermediate filaments
• Myosin
• Microtubule
• Thickest

138. Intermediate filaments
• Detected by immunohistochemistry
• Shows Histogenesis / origin of malignancy
• Desmin
• In skeletal muscle tumour /rhabdomyosarcoma
• Cytokeratin
• Epithelial tumours / carcinoma
• Dysmentin
• Sarcoma
• Melanoma
• HMB 45
• Lymphoma
• LCA /CD 45

139. Defect in microtubular fn
• Vinca alkaloids
• Colchicine in gout
• Kartageners syndrome
• Cystic fibrosis

140. Cytoskeletal abnormalities

141. Hematology

144. Howell jolly bodies
• Splenectomy
• Hyposplenism
• Megaloblastic anemia
• Hemolytic anemia

145. Cabots ring
• thin - darkly-stained ring that
follows the margin of the red cell
• In the form of partial loops, loops,
or figure eights
• granules in a linear array rather
than as complete rings

146. Basophilic stippling

147. Basophilic stippling

150. Heinz bodies