Kidney tumor
Childhood tumors
Metanephric adenofibroma

Topic Completed: 1 February 2012

Minor changes: 2 April 2020

Copyright: 2003-2019,, Inc.

PubMed Search: Metanephric adenofibroma kidney

Mandolin S. Ziadie, M.D.
Page views in 2019: 1,406
Page views in 2020 to date: 660
Cite this page: Ziadie MS. Metanephric adenofibroma. website. Accessed August 6th, 2020.
Definition / general
  • Biphasic, circumscribed tumor with focal embryonal epithelium identical to a combination of metanephric adenoma and bland spindled stroma
  • Part of a family of metanephric tumors including metanephric adenoma and metanephric stromal tumor
  • Morphology may merge with that of Wilms tumor, supporting the hypothesis that these are related lesions (Am J Surg Pathol 2001;25:433, Pediatr Dev Pathol 2012;15:65)
  • Previously known as nephrogenic adenofibroma
  • Rare (< 50 reported cases)
  • Mean age 14 years; range 235 years old
Clinical features
  • Associated with papillary renal cell carcinoma, polycythemia and hypertension, which resolve after nephrectomy (Am J Surg Pathol 1992;16:325)
  • Benign
  • Excision is curative
  • Chemotherapy not required
Gross description
  • Solitary, nonencapsulated, vaguely circumscribed, irregular or spherical firm mass with tan / gray / white / yellow cut surface
  • Variable cysts
Microscopic (histologic) description
  • Well circumscribed biphasic tumor with focal embryonal epithelium identical to metanephric adenoma and bland spindle cell stroma
  • Areas of intratumoral angiodysplasia, concentric cuffing of entrapped tubules ("onion skinning") and heterologous differentiation
  • Spans morphologic spectrum between benign pure stromal and pure epithelial lesions
  • Epithelial cells are bland with no mitotic figures
  • Entrapped tubules may have papillary hyperplasia
  • Numerous psammoma bodies
Microscopic (histologic) images

AFIP images

Spindle and myxoid
stroma with
adenomatous foci
are characteristic

Foci resembling
collecting duct
carcinoma are seen
in some lesions

Positive stains
Negative stains
Differential diagnosis
  • Mesoblastic nephroma: congenital myofibroblastic tumor with collagen; irregular infiltrating edges
  • Wilms tumor: epithelial predominant triphasic tumor with undifferentiated blastema
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