Prostate gland and seminal vesicles
Microscopic mimics of prostatic carcinoma
Nephrogenic metaplasia / adenoma

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

Revised: 19 September 2016, last major update September 2016

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed search: prostatic nephrogenic adenoma

Related topics: fibromyxoid nephrogenic adenoma
Cite this page: Nephrogenic metaplasia / adenoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/prostatenephrogenichyper.html. Accessed December 9th, 2016.
Definition / General
  • Benign polypoid, papillary, fungating or velvety lesion found in the bladder or prostatic urethra after urothelial injury
  • Has multiple histologic patterns
Essential Features
  • Previously thought to be a metaplastic reaction but actually derived from renal tubular cells
  • Tubules lined by cuboidal or hobnail cells
  • Many morphologic variants: papillary, tubular, signet ring-like
  • Hyaline rim surrounds the tubules
  • No mitotic activity
  • Only occasional solid areas or rare clear cells present
  • May focally involve the muscularis propria
ICD-10 coding
  • N329 Bladder disorder unspecified
Epidemiology
  • More common in males (2:1)
  • Any age
  • Following an urothelial injury (surgery, TUR, stone) or renal transplant
Sites
Pathophysiology
  • Derived from shedding or renal tubular cells as demonstrated by a study on patients with renal transplant (N Engl J Med 2002;347:653)
Etiology
  • Prior injury to the urothelium
Clinical Features
  • May present as a mass, with irritative voiding symptoms, or with hematuria
  • Usually small (<1 cm) but may be up to 7 cm
Diagnosis
  • Biopsy
Prognostic Factors
  • May recur
Case Reports
Treatment
  • Transurethral resection / TUR with regular followups
Gross Description
  • Friable soft tissue fragments
Micro Description
  • Tubules lined by cuboidal or hobnail cells
  • Associated acute and chronic inflammation
  • Many morphologic variants: papillary, tubular, signet ring-like
  • Hyaline rim surrounds the tubules
  • No mitotic activity
  • Only occasional solid areas or rare clear cells present
  • Atrophic tubules with eosinophilic colloid-like material mimicking thyroid follicles and mesonephric hyperplasia
  • May focally involve the muscularis propria
  • Associated with radiotherapy
  • There is a rare fibromyxoid variant with compressed spindle cells and rare cords or atrophic tubules in a fibromyxoid background
Micro Images

Images hosted on PathOut server:

Missing Image

Various images contributed by Andres Matoso, M.D.



Case of Week #209: 72 year old man with obstructive symptoms


Left to right: PIN-4 (AMACR+, p63-, CK903-), CK7+, PSA-



Images hosted on other servers:

Cytology Description
  • Numerous vacuolated, polygonal and columnar shaped cells singly or in small groups
  • Papillary fragments resembling low grade papillary urothelial carcinoma (Am J Clin Pathol 2016;145:373)
Positive Stains
Negative Stains
Differential Diagnosis