American Urological Association - Amyloidosis
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  • Rarely occurs in the bladder and is more often a primary localized process than a reflection of systemic amyloidosis.
  • Primary amyloidosis is due to AL-type amyloid.
  • Secondary amyloidosis is associated with hemodialysis, multiple myeloma, autoimmune causes and chronic infections.
  • Age: Typically in adults (5th and 6th decades) and presents with hematuria.
  • Localized amyloidosis may present as a solitary "tumor" mass that ulcerate the mucosa and masquerade as a malignancy.
  • Gross: Diffuse amyloidosis can be visualized as mucosal erythema.
  • Histology:
    • Deposition of eosinophilic amorphous materials in lamina propria and muscularis propria, with associated histiocytic and foreign body giant cell reactions (image A).
    • Vessel wall may also appear thickened by amyloid deposits, usually in systemic amyloidosis.
  • Ancillary work-up:
    • Congo red stain shows dense orange-brown under light microscopy and apple green birefringence under polarized light (image B), confirming the diagnosis.
    • Electron microcopy shows nonbranching rigid 8-12 nm fibrils.
    • Immunohistochemistry for typing (e.g. κ or λ light chains)
  • Localized bladder amyloidosis has high recurrence rate of ~50%.