Kidney tumor
Childhood neoplasms
Anaplastic sarcoma

Authors: Maxwell Rollins, M.D. (see Authors page)
Editor: Carla Ellis, M.D., M.S.

Revised: 9 January 2017, last major update August 2016

Copyright: (c) 2002-2017,, Inc.

PubMed Search: Anaplastic sarcoma kidney

Cite this page: Anaplastic sarcoma. website. Accessed December 11th, 2018.
Definition / general
Essential features
  • A high clinical suspicion for this entity should be entertained after diagnosis of anaplastic Wilm tumor, as many cases previously had this diagnosis (Am J Surg Pathol 2007;31:1459)
  • Typically large (mean 12 cm)
  • No epithelial structures, no nephrogenic rests, minimal to absent blastemal component
  • Most cases show chondroid differentiation (80% in first cases series), with either islands of hyaline cartilage or chondroid matrix (Am J Surg Pathol 2007;31:1459)
  • Mean age 12 years (median 5 years), range 1 - 41 years, with slight female predominance
Clinical features
  • Presents with renal mass at an advanced stage
  • Metastases to liver, lung and bone are common
Case reports
Gross description
  • Large (mean 12 cm), usually with cystic component
  • Almost half involve pelvicalyceal system
Microscopic (histologic) description
  • Fascicular pattern of spindle cells with anaplastic changes diffusely or in multiple foci (bizarre pleomorphic cells and atypical mitotic figures)
  • Foci of chondroid differentiation with both benign and malignant features, including islands of hyaline cartilage or chondroid matrix
  • Occasional foci of osteoid and primitive blastema-like areas
  • No epithelial structures, no nephrogenic rests
Microscopic (histologic) images

Images hosted on other servers:

(PDF) Spindle cells in collagenous stroma,
also anaplastic cells in cellular focus

Positive stains
Negative stains
Molecular / cytogenetics description
  • Recent evidence suggests that it is associated with germ line mutations in DICER1 (Hum Pathol 2016;53:114)
  • Absence of t(X;18) seen in synovial sarcoma and t(12;15) / ETV6-NTRK3 seen in mesoblastic nephroma
Differential diagnosis