3. amyloid Flashcards
Amyloid
Amyloid is a misfolded protein that deposits in the extracellular space that injure tissue
Physical Nature of Amyloid
a cross-β-pleated sheet conformation
Amyloidoma
Amyloidoma (tumoral amyloidosis) = solitary localized tumorlike deposit
staining in macroscope
Painting cut-surface with iodine imparts a brown- yellow colour, which changes to bluish-violet after application of sulphuric acid
type of stain plus how it appears in microscope
Congo red- on light microscope (pink or red colour) and on polarized microscope (apple green birefringence)
eosinophillic
Clinical Manifestation
usually asymptomatic
non specific weakness, loss of weight and light-headedness
classification of amyloidosis
systemic
localized
hereditary
systemic amyloidosis
kidney most common
systemic classiefied into
primary and secondary
primary amyloidosis
deposistion of AI amyloids derived from light chain ig
not secondary to other dieseases
secondary amyloidosis
Secondary to inflammatory conditions
AA (amyloid-associated) protein derived from precursor SAA (serum amyloid-associated) protein
inflammation causes SAA to change to AA then AA deposits
amyloidosis in kidney causes
Nephrotic syndrome and renal failure
amyloid deposition in spleen causes the 2 types
- Sago spleen: deposits largely limited to splenic follicles leading to Tapioca-like granules (in white pulp)
- Lardaceous spleen: involvement of walls of splenic sinuses and connective tissue framework of (red pulp), leading to large map like areas
amyloid in liver deposits in
space of disse
causes pressure atrophy
then hepatomegaly?
cardiac amyloidosis
causes Restrictive cardiomyopathy, arrhythmia, congestive cardiac failure and constrictive pericarditis
types of amyloidosis in cardiac amyloidosis
3
Senile cardiac amyloidosis-Non mutated TTR (wt-TTR)- wild type
Familial amyloid cardiomyopathy -Mutated TTR (m-TTR)-hereditary transthyretin amyloidosis (ATTRm)
AL amyloid
Dialysis associated amyloidosis
in dialysis the B2M not filtered well
its found in platlets and nucleated cells helps the MHC to be expressed well
B2M accumulates in joints causing joint paints for example
carpal tunnel syndrome
localized amyloidosis
Often caused by local production of immunoglobulin light chains (Localized AL)
Senile cerebral amyloidosis (alzheimers)
deposition of Ab amyloid which is derived from B amyloid precursor which is coded by chromosome 21 so down syndrome patients will develop alzheimers early
Cerebral amyloid angiopathy (CAA)
Deposition of amyloid fibrils within the walls of blood vessels of the brain and meninges
type 2 DM amyloid
amylin which is a byproduct of insulin when excess in DM2 , deposits in the islets of pancreas
medullary thyroid carcinoma
tumour in c cells - more calcitonin - calcitonin deposits in the gland
