American Urological Association - Amyloidosis
- 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.
- 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%.