Prostate
Benign lesions / conditions
Amyloid

Author: Andres Matoso, M.D. (see Authors page)

Revised: 25 January 2017, last major update January 2017

Copyright: (c) 2003-2017, PathologyOutlines.com, Inc.

PubMed Search: prostatic amyloid
Cite this page: Amyloid. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/prostateamyloid.html. Accessed October 23rd, 2017.
Definition / general
  • Primary amyloidosis of the prostate is a rare disease
  • Vascular amyloid deposits are present in 2% - 10% of prostates with nodular hyperplasia or adenocarcinoma
  • Higher incidence of amyloid deposits in patients with myeloma, primary amyloidosis of kidney or chronic diseases
  • Amyloid deposits usually subepithelial or vascular
  • Involves seminal vesicles in about 10% of radical prostatectomies, usually represents a localized form
  • Note: corpora amylacea may stain positive with Congo red
Essential features
  • Pale amorphous hyaline, eosinophilic substance that accumulates and can pressure the adjacent epithelium
  • Often displays processing cracks
  • More common in seminal vesicles and vas deferens
  • Subepithelial and vascular deposits
Epidemiology
  • Amyloidosis of the seminal vesicles involves 10% of radical prostatectomy specimens
Sites
  • More common in seminal vesicles and vas deferens
  • Deposits are more commonly subepithelial and vascular
Pathophysiology
  • Abnormal folding of proteins that deposit as fibrils in the extracellular tissue and may accumulate preventing normal function
  • Amyloidosis includes multiple biochemically distinct proteins but with similar morphologic appearance
  • Different forms of amyloidosis include:
    • Primary systemic amyloidosis (no evidence of preceding or coexisting disease, paraproteinemia or plasma cell neoplasia)
    • Amyloidosis associated with multiple myeloma
    • Secondary to coexisting previous chronic inflammatory or infectious conditions, hemodialysis
    • Localized form
Clinical features
  • Most commonly asymptomatic
  • Can simulate prostate or bladder cancer invasion of seminal vesicles on MRI
Diagnosis
  • Histology: amorphous pale eosinophilic material often with cracks from processing
  • Histochemical stain with Congo red shows green birefringence on polarized microscopy
Radiology description
  • Can simulate prostate or bladder cancer invasion of seminal vesicles on MRI
Case reports
Treatment
  • Based on the underlying condition
Gross description
  • Usually not seen grossly
  • When involvement is massive, the organ can be enlarged and firm and cut section could show a waxy appearance
Microscopic (histologic) description
  • Pale amorphous hyaline, eosinophilic substance that accumulates and can pressure the adjacent epithelium
  • Often displays processing cracks
  • Subepithelial location
  • Can compress the adjacent epithelium
Microscopic (histologic) images

Images hosted on Pathout server:
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Contributed by Andres Matoso, M.D.



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Various images

Positive stains
  • Congo red, immunohistochemistry for specific amyloid forms
Electron microscopy description
  • Electron microscopy shows amyloid fibrils that measure 7.5 to 10 nm
Differential diagnosis
  • It is important to exclude an underlying etiology including plasma cell neoplasia or an inflammatory condition