Microscopic Description:

Large masses of eosinophilic proteinaceous material with hemorrhage in the lamina propria.

Variable presence of foreign body giant cell reaction to amyloid.

May exhibit atypical epithelium due to urothelium attenuation.

Perivascular amyloid deposits are rare, especially in systemic amyloidosis.

Inflammatory cells are rarely present.

Positive Stains- Congo red staining displays apple green birefringence under polarized light.

Amyloid panel includes kappa and lambda light chains, prealbumin, beta-2-microglobulin, and SAA1.

Immunofluorescence staining with Thioflavin T.

Discussion:

Amyloidosis refers to a collection of benign lesions distinguished extracellular deposition of amyloid proteins.

Amyloidosis is categorized into two types based on which organs or tissues are affected: systemic and localized.

Clinically, understanding this condition is crucial because primary amyloidosis that solely affects the bladder can mimic an invasive tumor on imaging and during cystoscopy, leading to a misdiagnosis of malignancy.

Commonly affected organs include the urinary bladder, lungs, larynx, skin, tongue, and periorbital region. Within the urinary tract, amyloid deposits typically begin in the kidneys and extend to the renal pelvis, ureters, urinary bladder, and urethra.

Secondary amyloidosis almost always involves the kidneys, while primary amyloidosis affects the kidneys in about 50% of cases.

However, primary amyloidosis frequently manifests in the urinary bladder.

Can be primary (AL type amyloid), secondary (AA type amyloid), or familial (ATTR type amyloid).

Systemic secondary bladder amyloidosis is linked to autoimmune diseases and chronic infections.

Familial cases are predominantly associated with mutations in the transthyretin gene.

Localized

  • The etiology is largely unknown
  • Predominantly AL type amyloid

Clinical Features

  • Patients typically present with gross, painless hematuria
  • Clinical presentation may resemble bladder cancer
  • Primary amyloidosis often exhibits a high rate of local recurrence
  • Prognosis of secondary amyloidosis depends on the underlying primary cause
References:

https://www.pathologyoutlines.com/topic/bladderamyloidosis.html

Yu ZY, Yan L, Wang HK, Hang G, Wang YY, Wen Q, Chen B. Bladder triangle amyloidosis: A case report and literature review. Medicine (Baltimore). 2022 Dec 9;101(49):e32179. doi: 10.1097/MD.0000000000032179. PMID: 36626417; PMCID: PMC9750701

Altwairgi A. Primary amyloidosis of the urinary bladder presenting as painless heamaturia. Int J Health Sci (Qassim). 2011 Jul;5(2):181-5. PMID: 23267295; PMCID: PMC3521836

CASE IMAGES