all you need to know about amyloidosis

2.  Amyloidosis refers to an abnormal deposit of insoluble fibrillar
protein in extracellular spaces of various tissues and organs.
 The insoluble fibrills are formed by the misfolded proteins which
are usually soluble in their normal folded configuration.
 It is associated with a number of clinical conditions like multiple
myeloma, familial Mediterranean fever, rheumatoid arthritis,
tuberculosis, brocheactasis etc.

3. All amyloid have same morphological and staining property but
amyloidosis is not a single disease.it is a group of disease having in
common, the deposition of similar appearing proteins in which
biochemical structure and mechanism of formation are different.

4. On electron microscopy
 All types of amyloid are composed of fibrills
that are continuous, non branching, , rigid,
insoluble ,linear and measures about 7-10nm
in diameter.
On X-ray crystallography
 Amyloid fibrills shows beta – pleated sheet
configuration which produces periodicity that
gives the characteristic staining properties of
amyloid with Congo red and apple green
birefringence under polarizing microscopy.

5. Fibrillar proteins bind with variety of substances
 About 95% of the amyloid material consists of fibril
protein.
 Remaining 5% consist of serum amyloid P,
proteoglycans, glycosaminoglycan, etc.

6. MAJOR
FORMS
AL (AMYLOID
LIGHT CHAIN)
PROTEIN
AA(AMYLOID-
ASSOCIATED )
PROTEIN
A-Beta amyloid
MINOR
TYPES
Transthyretin
Beta
macroglobulin
Other miner
types

7. AL(amyloid light chain) protein-
 Consist of complete immunoglobulin light chains or the amino terminal fragments of
light chain or both.
 Produced by plasma cells and associated with some monoclonal b-cell proliferation
like in case of plasma cell tumors.
AA(amyloid associated) protein-
 Derived from a larger precursor in the serum called SAA(serum amyloid associated)
protein synthesized by liver.
 Associated with chronic inflammation in which there is increased synthesis of SAAP
under the influence of cytokines released during inflammation.

8. TRANSTHYRETIN(TTR)-
 It is a normal serum protein which transports thyroxin and retinol.
 Mutation in the gene encoding TTR alters its structure
misfolding of protein.
 Found in - familial amyloid polyneuropatheis, senile systemic amyloidosis.
A BETA-2 MICROGLOBULIN-
 Seen in cases of long term haemodialysis (10-12) years.
 It is a small protein which is a normal component of MHC class 1
 It cannot be filtered by the haemodialysis membrane hence its serum concentration
increases leading to its deposition in bones and joints.
AMYLOID BETA PEPTIDE-
 It is derived from amyloid beta precursor protein.
 It is deposited in cerebral amyloid angiopathy and neurofibrillary tangles in Alzheimer's
disease.

12.  Clinical manifestations initially may be non-specific like weakness, weight
loss. Specific symptoms appear later and are related to cardiac, renal and
gastrointestinal involvement.
 Renal involvement- it gives rise to proteinuria which may lead to nephrotic
syndrome. In advanced cases, the obliteration of glomeruli causes renal
failure and uraemia.
 Cardiac amyloidosis- it may present as congestive cardiac failure ,
conduction disturbances and arrhythmias.
 Gastrointestinal amyloidosis-it may be present as malabsorbtion, diarrhoea
and digestive disturbances.

14. CONGO RED STAIN-
›It is a special stain used for the
diagnosis of amyloidosis.
›Amyloid stain pink or red with
Congo red stain under ordinary light.
›But under polarizing microscope it
gives APPLE GREEN BIREFRINGENCE.
›It is due to the cross beta
configuration of amyloidosis.
IMMUNOHISTOCHEMISTRY
›It can distinguish AL, AA, ATTR types of amyloid.
›Antibody stain is used against specific amyloid which acts as antigen here.
›E.g.- anti-AA, anti-lambda, anti kappa, transthyretin antibody stains etc.

15.  METACHROMATIC STAINS-
 Methyl violet and cresyl violet is used.
 The dye reacts with the amyloid and produces color change.
 It imparts rose pink color to the amyloid deposits.
 FLOURESCENT STAINS-
 Dye THIOFLAVIN-T binds to the amyloid and imparts yellow color under uv light.
 H AND E STAIN-
 Amyloid with H and E stain appears as extracellular, homogenous, structure less,
and eosinophilic hyaline material.
 STAIN ON GROSS-
 LUGOL’S IODINE imparts mahogany brown color to the amyloid containing area
which on addition of sulphuric acid turns blue.

16.  Amyloid deposition in
heart
H and E Stain
 Amyloid deposition on
kidney
Congo red stain

17. Apple green birefringence under polarizing microscope.

19. KIDNEY
GROSS-
 Cut surface is pale, waxy and translucent.
 it appears to be shrunken due to ischemia, caused
by vascular narrowing induced by the amyloid
deposit within arteriolar walls.
MICROSCOPY-
 GLOMERULI-main site of amyloid deposition.
 First focal deposits occurs within mesangial matrix,
accompanied by nodular thickening of glomerular
basement membrane.
 Progressive accumulation of amyloid causes capillary
narrowing thereby showing obliteration of capillary
lumen.
 Glomerulus shows broad ribbons of amyloid.

20. SPLEEN
GROSS- it may show one of two pattern
of deposition.
 Sago spleen- amyloid deposits are limited to the splenic
follicles which grossly appear like sago granule hence
known as sago spleen. Microscopically, the amyloid is
deposited into the wall of the wall of arterioles in the
white pulp.
 Lardaceous Spleen- The amyloid is deposited into walls
of the splenic sinuses and connective tissue framework
into the red pulp. This may result in moderate to marked
enlargement of spleen. Fusion of early deposits give rise
to large, map like area of reddish color on cut surface.
This resemble pig fat and hence called as lardaceous
spleen. Microscopically, it shows amyloid deposits in the
wall of the sinuses.
 Light microscopy-This deposits appear homogeneous
pink which when stained with Congo red and viewed
under polarizing microscope give rise to characteristic
green birefringence.

21. LIVER
 Gross-It may cause moderate to
marked enlargement .it appear
pale ,grey ,waxy.
 MICROSCOPY
• Amyloid first deposits in the space
of disse and then progressively
encroaches on adjacent hepatic
parenchymal cells and sinusoids.
 progressive accumulation leads to
deformity, pressure atrophy and
disappearance of liver cells.

22. HEART
 It may be involved in systemic
amyloidosis(AL) type or may be
the major organ involved in
SENILE SYSTEMIC
AMYLOIDOSIS.
 GROSS-heart may be enlarged
and firm. subendocardial deposits
may appear as gray pink like dew
drops.
 MICROSCOPY-amyloid is
deposited between the muscle
fibers of myocardium and their
progressive accumulation causes
pressure atrophy of myocardial
fibers.

23.  Tissue biopsy provides definitive diagnosis
 Fat pad biopsy. Fat, aspirated from the abdominal wall is the most easily accessible tissue and biopsy is
positive in >80% of patients with systemic amyloidosis.
 Staining of the tissue specimen with congo red reveals an apple green birefringence when viewed by
polarised light microscopy.
 Peripheral blood film- Howell Jolly bodies seen in hyposplenism.
 BNP, pro-BNP, Troponin- increased in cardiac amyloidosis.
 ECG- low voltage QRS complex, conduction block.
 Echocardiography- speckled pattern is seen.
 Urine analysis- proteinuria in renal amyloidosis.
 Serum/urine protein electrophoresis- presence of monoclonal light chains in AL amyloidosis
 Bone marrow biopsy- identification of dominant plasma cell in AL amyloidosis

24. It varies with the type of amyloidosis.
 AL amyloidosis carries the worst prognosis if left untreated with median survival
of two years.
 Outcomes in patients with AA amyloidosis depends on the underlying disease
and symptoms may improve if the underlying condition is treated.
 People with ATTR have the best prognosis and may survive over a decade.
 Cause of death in most cases of amyloidosis is cardiac failure or sudden death
from a fatal arrhythmias.

25.  Liver transplant in ATTR amyloidosis.
 Use of PO doxycycline (100 mg OD) in amyloid
arthropathy