Kidney tumor
Childhood neoplasms
Anaplastic sarcoma

Topic Completed: 1 August 2016

Revised: 8 December 2019

Copyright: 2002-2019,, Inc.

PubMed Search: Anaplastic sarcoma kidney

Maxwell Rollins, M.D.
Carla L. Ellis, M.D., M.S.
Page views in 2019: 556
Page views in 2020 to date: 125
Cite this page: Rollins M, Ellis C. Anaplastic sarcoma. website. Accessed February 24th, 2020.
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
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