ASSTT PROFESSOR DEPTT OF PATHOLOGY BVC PATNA What is amyloid Amyloid G Amylon STARCH means starchlike Amyloid is a pathologic glycoprotein deposited in the extracellular spaces and forms fibrils on polymerization ID: 914311
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Slide1
AMYLOIDOSIS
DR. SANJIV KUMAR
ASSTT. PROFESSOR,
DEPTT. OF PATHOLOGY, BVC, PATNA
Slide2What is amyloidAmyloid (G.
Amylon
- STARCH) means starch-like. Amyloid is a pathologic glycoprotein deposited in the extracellular spaces and forms fibrils on polymerization.
Slide3HISTOLOGICAL CHARACTERISTICSOF AMYLOID
Amyloid
is specially stained with Congo Red. Under polarized light, green birefringence is noticed because of alignment of fibrils
.
β-pleated sheet configuration is seen in X-ray diffraction.
The P-component which is a
glycosa
-amino-glycan (GAG) facilitates polymerization of amyloid.
The
GAG makes the amyloid to stain with
iodine.
The amyloid is resistant to enzymatic digestion and progressively accumulate in tissues until the underlying disease process persists.
Slide4Types/Sources of amyloidAmyloid associated (AA): It occurs in chronic diseases and septic conditions. Precursor is serum amyloid associated protein (SAA).
Amyloid light-chain (AL): It is produced in
plasmacytoma
and the precursor is immunoglobulin light-chain.
Slide5AMYLOIDOSIS
Definition
It
is an immunological disorder in which homogeneous, translucent amyloid substance is deposited between capillary endothelium and adjacent cells.
Pathogenesis
The main event occurring in amyloidosis is the deposition of amyloid fibrils due to abnormality of protein processing.
The sources of amyloid may be acute phase proteins,
immunoglobulins
and endocrine secretes
.
Slide6The amyloid forms a β-pleated sheet despite their chemical heterogeneity. This makes the fibril resistant to digestion by macrophages and phagocytic cells and hence accumulates in tissues.The
amyloid, deposited around the blood vessels is more dangerous.
Pressure
atrophy of the adjacent cells and ischaemic anoxia results in degeneration and necrosis.
Due
to interference with gaseous exchange, supply of
nutritents
and removal of waste products and
stenotic
vessels, degeneration and necrosis of cells will occur amyloid precursor protein.
Slide7Types of amyloidosisPrimary amyloidosis
Secondary
amyloidosis
Slide8Primary amyloidosisIt
results from antigen-antibody reaction and deposition of its precipitates.
The
condition is not associated with any diseases e.g. repeated exposure to antigens as in antisera and antitoxin production in horses and B cell
dyscrasia
(
plasmacytoma
) in humans in which
immunoglobin
light chain deposition occurs.
The soluble immunoglobulin becomes insoluble with defective degradation.
Slide9Secondary amyloidosisThe condition may be associated with chronic diseases like tuberculosis, septic conditions and
neoplasia
.
This
occurs in two phases.
In
the initial
preamyloid
phase, there is accumulation of reticular cells and macrophages in the spleen and other lymphoid tissue with consequent rise in plasma SAAs and globulins
.
During the second phase, known as amyloid phase, PAS staining cells, amyloid deposition and fall in the SAAs level are found.
Slide10Grossly, the amyloid deposition may be diffuse or focal. The amyloid is deposited around the central artery of splenic follicles and it forms sheet like deposits which is referred as bacon
spleen
and it may protrude resembling like a grain of sago known as
sago spleen
.
The
organ is waxy in consistency and the cut surface is
grayish
.
Splenic
corpuscles become large,
gray
and translucent.
Liver
is enlarged with rounded edges, doughy in consistency, pits on pressure and ruptures easily because of its friable nature
.
In
renal amyloidosis, the organ is swollen, mottled, pale and yellow to orange in colour
Slide11Effects of amyloidosisHypovolumic
or haemorrhagic shock may occur following hepatic rupture
.
Hepatocellular
atrophy occurs from pressure and nutritional deficiency
.
In
renal amyloidosis,
interfere
with glomerular filtration.
The
enlargement and ischaemic anoxia leads to tubular epithelial degeneration and necrosis, marked proteinuria,
nephrotic
syndrome,
uremia
and death
In pancreatic amyloidosis,
leads
to islet cell destruction and development of Diabetes mellitus.
Blindness
may be encountered in horses in with
conjuctival
amyloid deposition.