Amyloid Flashcards

1
Q

What is amyloidosis?

A

EXTRACELLULAR deposition of abnormal proteins either in a single organ (localised amyloidosis) or throughout the body (systemic amyloidosis)

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2
Q

What is the composition of amyloid and simple pathogenesis involved?

A

Composition

  • Fibrillar component (90-95% of amyloid): B sheet fibrils
  • Nonfibrillar component (5-10% amyloid)

Pathogenesis: accumulation of amyloid = cellular injury and apoptosis

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3
Q

Types of amyloidosis

A

Light chain amyloidosis (AL)
- Associated with plasma cell dyscrasias, eg: MM, waldenstrom macroglobulinaemia

Reactive amyloidosis (AA)
Etiology: secondary disease
- Chronic inflammatory conditions, eg: IBD, RA, SLE, vasculitis, FMF
- Chronic infectious diseases, eg: TB, bronchiectasis, leprosy, OM
- Tumours: RCC, lymphomas

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3
Q

Features of light chain amyloidosis (AL)

A

Light chain amyloidosis (AL)

  • Associated with MM, waldenstrom macroglobulinaemia
  • Increased production of light chains of immunoglobulins leading to deposition of amyloid light chains
  • Rapidly progressive clinical course
  • Heart: restrictive cardiomyopathy, AV block
  • Kidney: nephrotic syndrome, type II RTA, diabetes insipidus
  • Tongue: macroglossia
  • Autonomic neuropathy
  • GIT: malabsorption
  • Bleeding disorders/splenomegaly
  • MSK: carpal tunnel
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4
Q

Features of reactive amyloidosis (AA amyloidosis)

A

Etiology: secondary disease

  • Chronic inflammatory conditions, eg: IBD, RA, SLE, vasculitis, FMF
  • Chronic infectious diseases, eg: TB, bronchiectasis, leprosy, OM
  • Tumours: RCC, lymphomas

Pathophysiology: chronic inflammatory process –> increased production of acute phase reactant SAA –> deposition of AA protein in various organs

Clinical Features:

  • Kidney: nephrotic syndrome, type II RTA, nephrogenic DI
  • Adrenal: primary adrenal insufficiency
  • Liver + Spleen: hepatomegaly, splenomegaly
  • GIT: malabsorption
  • MSK: carpel tunnel syndrome
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5
Q

What should be considered in patients with long-standing inflammatory and/or infectious disease who present with kidney, liver or GI involvement?

A

Amyloidosis

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6
Q

Which one is rapidly progressive clinical course = light chain (AL) or reactive (AA) amyloidosis?

A

Light chain amyloidosis

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7
Q

Features of haemodialysis associated amyloidosis

A
  • B2 microglobulin becomes AB2M amyloid protein
  • Associated with long term HD, end stage renal disease
  • ~10 years after starting HD
  • Joints and tneonds
  • Almost all individuals on long term HD will develop amyloid at some point
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8
Q

Diagnosis of amyloidosis

A

If systemic disease - abdominal fat or rectal mucosa biopsy with congo red stain
- Apple green birefringence under polarised light

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9
Q

Treatment for amyloidosis

A
  • Treat the underlying disease

- If amyloidosis progresses rapidly, eg: light chain amyloidosis - corticosteroids, melphalan

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