Nephrogenic Adenoma

Clinical Futures
 
  • A rare benign lesion, usually limited to the mucosa and lamina propria;
  • Mostly associated with a history of urinary tract insults, including surgery, trauma, calculi, inflammation, urinary bladder diverticulum, intravesical therapy, and renal transplantation;
  • Mostly in the urinary bladder and middle-aged men are more commonly affected.
Gross Findings
 
  • Typically small; however, lesions up to 7 cm have been documented. The lesion may be polypoid, flat, isolated, or multifocal.
Microscopic Findings
 
  • Small epithelial-lined tubules and cysts resembling the remnants of embryonal renal tubules;
  • The lining cells are often cuboidal with scanty cytoplasm and small nuclei without significant cytologic atypia and mitosis.
  • There may be chronic inflammation accompanying the lesion.
Subtypes
 
  • Tubular  pattern: most common pattern. The tubules were usually small, hollow, and round, but some were solid and occasionally elongated. Their arrangement varied from orderly, sometimes laminar, to pseudoinfiltrative. Occasionally, the tubules are tiny and when they contain basophilic secretion they can mimick signet-ring cells. A basement membrane was appreciable around the tubules but was rarely prominent.
  • Cystic pattern:  The tubules and cysts most commonly contained eosinophilic secretion and occasionally basophilic.
  • Papillary to polypoid pattern: Edematous polyps are common but thin . Delicate filiform papillae are present. A complex branching pattern with prominent budding of small papillae are occasionally present. The papillary-polypoid pattern are usually associated with a tubular component.
  • Solid/diffuse pattern: rare.
Differential Diagnosis
 
  • Clear cell carcinoma
  • Urothelial carcinoma, nested or microcystic variants
  • Prostatic adenocarcinoma
Immunohistochemistry Straining
 

  • Nephrogenic adenoma shares the same immunohistochemical profile as distal renal tubules: both are positive for P504S and epithelial membrane antigen and negative for p63, CD10, and prostate-specific antigen. Prostatic adenocarcinoma is positive for P504S and prostate-specific antigen, and normal prostatic gland tissue is positive for prostate-specific antigen and negative for P504S. p63-stains basal cells in normal prostatic gland tissue but does not react with prostatic adenocarcinoma tissue. The CD10 inconsistently stains normal and neoplastic prostatic gland tissue. Epithelial membrane antigen stain is negative in prostatic carcinoma, with rare occasional reactivity in normal prostatic glands
Election Microscopy
   
Cytogenetics
   
Treatment and Prognosis
   
Reference
  http://pathology2.jhu.edu/sp/continue.cfm, week 311
  Archives of Pathology and Laboratory Medicine: Vol. 130, No. 6, pp. 805–810.
  Modern Pathology (2006) 19, 356–363. doi:10.1038/modpathol.3800535; published online 6 January 2006
  Mod Pathol. 1995 Sep;8(7):722-30.