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Kidney tumor - adult malignancies

Adult renal cell carcinoma

Sarcomatoid renal cell carcinoma


Reviewers: Sean Williamson, M.D. (see Reviewers page)
Revised: 30 June 2012, last major update June 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● 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)

Epidemiology
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● 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

Poor prognostic factors
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● 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
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● 45 year old woman with sarcomatoid chromophobe renal cell carcinoma with squamous differentiation (Arch Pathol Lab Med 2008;132:1672)
● 71 year old woman With divergent growth pattern (Arch Pathol Lab Med 2005;129:1057)
● 78 year old man with papillary renal cell carcinoma with sarcomatoid transformation (Arch Pathol Lab Med 2000;124:1830)

Gross description
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● Fleshy, gray-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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With clear cell carcinoma


Tumor is firm and fibrous and there is extensive invasion of renal structures

With clear cell carcinoma

Micro description
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● 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

Micro images
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Resembling undifferentiated spindle cell sarcoma

   
Mixture of carcinomatous and sarcomatous elements


Papillary and sarcomatoid tumor

       
Sarcomatoid chromophobe carcinoma


Pseudoangiosarcomatous foci


Clusters of atypical epithelial cells


Various lines of differentiation

   
Resembles malignant fibrous histiocytoma


AE1-AE3, CD10, CD117

Positive stains
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● AE1-AE3, vimentin (56%), EMA (50%), CAM5.2 (40%)
● Also actin (33%) and LeuM1 (22%) in spindled areas

Negative stains
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● High molecular weight keratin 34betaE12, S100 (usually) (Arch Pathol Lab Med 1993;117:636)

Electron macroscopy description
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● Desmosomes, microvilli

Electron macroscopy images
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Osteoid deposition, poorly differentiated symmetric junctional contacts

Molecular description
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● 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
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Primary renal sarcoma: usually leiomyosarcoma, no epithelial component after careful sampling
● Primary retroperitoneal soft tissue sarcoma: no epithelial component after careful sampling
● Clear cell carcinoma with early spindle cell change: stroma is not malignant (Hum Pathol 2007;38:1372)

End of Kidney tumor - adult malignancies > Adult renal cell carcinoma > Sarcomatoid renal cell carcinoma


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