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
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
