Transcript 04-Hyaline change and Amyloidosis

Hyaline change
It is a change in the physical appearance of the
tissues which become homogenous, glossy,
translucent and pink with H&E staining
There is fusion of cells and tissues probably
due to coagulation and dehydration of proteins
Types
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Three types of hyaline change are
recognized
Keratohyaline
Cellular hyaline
Connective hyaline
1-Keratohyaline
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Excessive keratinization (cornification) of skin occurs
in different conditions
Mechanical irritation causes corns and calluses on
hands (workmen) , feet (shoes) and place of saddle
and harness (horses)
Chlorinated naphthalene poisoning- hyperkeratosis
in cattle
Pappiloma virus causes warts in cattle and dogs
Squamous cell carcinoma produces keratohyaline in
the form of epithelial pearls
Vit.A deficiency causes keratinization of esophagus
and trachea in chicken
2-Cellular hyaline
Cells in many organs are desquamated,
particularly in the lumens and cavities of
the glands where they fuse into
homogenous round masses.
 These masses stain deep brown with
iodine and are called corpora amylacea.
 Commonly found in mammary glands,
prostate, lungs, kidneys, and ventricles
of brain.
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3-Connective hyaline
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This is observed in old scars, renal
glomeruli in chronic nephritis and in the
media of blood vessels in
arteriosclerosis.
Significance
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Hyaline change occurs under a wide
variety of pathological conditions but is
not considered significant. It makes the
tissues inelastic and lacks nerve and
blood supply
General Pathology
(PATH 303)
Lecture # 5
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Amyloid and Amyloidosis
1. Amyloid and Amyloidosis
 Hyaline, waxy material.
 Homogenous nature -15 different types.
 Physical nature-- non-branching fibrils.
Beta-pleated sheet structure
(A regular element of secondary structure in proteins,
in which two or more extended strands of the
polypeptide chain lie side by side (running either
parallel or antiparallel), held together by a regular
array of hydrogen bonds between backbone NH and
C=O groups, to form a ridged planar surface.)
2. Chemical nature of amyloid
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95% fibriller glycoprotein
5% is non-fibriller glycoprotein ( P component) and proteoglycans
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AA ( amyloid associated) – non- immunoglobulin protein
synthesized in liver and present in serum- SAA.
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Most common form found in animals.
Occurs in chronic inflammatory conditions like T.B. and osteomyelitisSecondary amyloidosis.
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AL (Amyloid light chain) – contains immunoglobulin light
chains- Primary amyloidosis.
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Produced by plasma cells in plasmacytomas.
Most common form in humans.
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3. Occurrence
 Most common in man but all species
can be affected.
 Among animals, common in dog, cattle,
horse and chicken.
 May be local or generalized.
4. Causes
 Secondary amyloidosis in animals is
associated with chronic inflammatory
disorders.
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Activation of macrophages produces cytokines IL1 and IL-6
Under the influence of cytokines liver cells
produce more SAA.
More SAA alone does not cause amyloidosis
There is enzyme defect in affected animals
producing incomplete breakdown of SAA.
Production of insoluble AA protein
Stimulus
Unknown (carcinogen ?)
Monoclonal B-Lymphocyte proliferation
Plasma Cells
Soluble Precursor
Immunoglobulin light chains
Limited Proteolysis
Insoluble Fibrils
Insoluble AL Protein
5. Primary amyloidosis in man
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Deposition of amyloid light chain (AL) or their
fragments or both.
Monoclonal cell proliferation- multiple
myeloma
Plasma cells also secrete Lamda and Kappa
light chains- Bence Jones proteins.
Only a few patients with Bence Jones
proteins develop amyloidosis.
Defective proteolysis produces insoluble AL
Stimulus
Chronic Inflammation
Macrophage activation
Interleukins 1 and 6
Liver cells
Soluble Precursor
SAA Proteins
Limited Proteolysis
Insoluble Fibrils
Insoluble AA Protein
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6. Harmful effects:
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Pressure atrophy of surrounding cells and
tissues
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Inhibition of exchange of gases, nutrients
and waste materials.
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Compression and stenosis of hollow organs.
Gross and microscopic appearance
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Amyloid is most commonly seen in spleen,
kidney, liver and adrenal. Spleen is normally
involved in the chicken with tuberculosis.
 In spleen, amyloid gradually forms a cuff
around the central artery of spleenic follicles
 The mass appears as grey foci, resembling
grains of sago- called sago spleen.
 The foci gradually increase in size and may
rupture and cause fatal hemorrhages.
Special stains
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Amyloid stains pink with eosin, yellow
with van Gieson, red with Congo red.
Crystal violet and methyl violet also
stain it red.
Significance
Amyloid deposition is a permanent
change and persists for life.
 It may cause uremia (in kidney), rupture
(in liver) and diabetes in case of
pancreas.
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