Kidney tumor
Adult renal cell carcinoma
Sarcomatoid renal cell carcinoma

Author: Sean R. Williamson, M.D.

Revised: 4 September 2018, last major update June 2012

Copyright: (c) 2003-2018,, Inc.

PubMed Search: Sarcomatoid renal cell carcinoma kidney

Cite this page: Williamson, S.R. Sarcomatoid renal cell carcinoma. website. Accessed September 26th, 2018.
Definition / general
  • Not a distinct histologic entity but the common pathway of transformation of different subtypes of renal cell carcinoma
  • Also called spindle cell carcinoma or carcinosarcoma
  • 5% of renal cell carcinomas have a sarcomatoid component; often associated with clear cell carcinoma or chromophobe carcinoma (Am J Surg Pathol 1997;21:1188)
  • Report presence of even a focal sarcomatoid component, which is associated with a poorer prognosis (Am J Surg Pathol 2001;25:275)
  • Mean age 60 years, 60% men, usually stage 3 or 4
  • Metastases to lungs most common
  • Aggressive with median survival of 19 months; 5 / 10 year survival is 22% / 13% vs. 79% / 76% for other renal cell carcinomas
Prognostic factors
  • High stage, presence of 50% or more sarcomatoid component, distant metastases at time of nephrectomy, histologic tumor necrosis (Am J Surg Pathol 2004;28:435)
Case reports
Gross description
  • Fleshy, grayish white, infiltrative margins; mean 9 cm
  • If it looks sarcomatoid, must prove otherwise
  • May have clear cell component (yellow, hemorrhagic, necrotic)
Gross images

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Tumor is firm and fibrous

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With clear cell carcinoma

Microscopic (histologic) description
  • Atypical spindle cells or tumor giant cells with marked nuclear pleomorphism and abnormal mitotic figures
  • May resemble MFH or fibrosarcoma with poorly formed fascicles
  • Occasionally undifferentiated with rhabdomyosarcomatous component, bone or cartilage
  • Must have an epithelial component for this diagnosis (may need generous sampling)
  • Should have sarcomatoid overgrowth of at least one low power field to call sarcomatoid
  • Usually considered to be nuclear grade 4
Microscopic (histologic) images

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Mixture of carcinomatous and sarcomatous elements

Resembles malignant fibrous histiocytoma

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Sarcomatoid chromophobe carcinoma

Papillary and sarcomatoid tumor

Various lines of differentiation

AE1 / AE3, CD10, CD117

Positive stains
Negative stains
Electron microscopy description
  • Desmosomes, microvilli
Electron microscopy images

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Osteoid deposition

Molecular / cytogenetics description
  • Similar X chromosome inactivation patterns in both sarcomatoid and "parent" tumor suggesting common cell origin (Cancer 2005;104:1195)
  • Also significant heterogeneity in the tumor components, suggesting genetic divergence (Mod Pathol 2007;20:303)
Differential diagnosis