10- AMYLOIDOSIS

• Amyloidosis


  A group of disorders characterized by extracellular deposits of amyloid fibrils (a protein in abnormal beta-sheet fibrils form, resistant to degradation)
• Amyloidosis


  • Normal sized kidneys
  • Nodular sclerosis (Kimmelstiel–Wilson) like diabetes
• Types of amyloidosis


  • AL (primary) amyloidosis
  • AA (secondary) amyloidosis
• AL Amyloidosis


  Primary amyloidosis, due to abnormal clonal proliferation of plasma cells leading to deposition of immunoglobulin (Ig) light chains: λ (75% of cases) or ҡ (associated with multiple myeloma)
• AA Amyloidosis


  Reactive/secondary amyloidosis, due to chronic inflammation from conditions like rheumatoid arthritis, tuberculosis, osteomyelitis, or familial Mediterranean fever
• Clinical features of primary amyloidosis

  • Renal: proteinuria, nephrotic syndrome or progressive renal failure
  • Heart: CHF
  • Intestine: malabsorption, hepatomegaly
  • Nerves: carpal tunnel syndrome, peripheral neuropathy
  • Skin: easy bruising
• Diagnosis of amyloidosis involves positive Congo Red staining of amyloid deposits within the glomerulus with apple-green birefringence under polarized light microscopy, and electron microscopy showing randomly organized amyloid fibrils