Kidney tumor
Childhood neoplasms
Metanephric adenofibroma

Author: Mandolin Ziadie, M.D. (see Authors page)

Revised: 13 January 2017, last major update February 2012

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

PubMed Search: Metanephric adenofibroma kidney

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Cite this page: Metanephric adenofibroma. website. Accessed January 23rd, 2019.
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

Images hosted on PathOut server:

Spindle and myxoid
stroma with
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