Sarcomatoid Renal Cell Carcinoma
Definition
- Renal cell carcinoma of any type exhibiting at least focal sarcomatoid/spindle cell differentiation
Alternate/Historical Names
- Carcinosarcoma
- Spindled carcinoma
Diagnostic Criteria
- Represents a form of high grade transformation, not a distinct subtype of renal cell carcinoma
- May occur in any of the standard subtypes of renal cell carcinoma
- Reported to occur in 5-8% of renal cell carcinomas
- Less common in our experience
- Should not be reported as the subtype of renal cell carcinoma
- Requires evidence of epithelial differentiation
- Concurrent areas of renal cell carcinoma of any type, OR
- Immunohistochemical positivity for keratin or EMA
- (Keratin and EMA expression may be appropriate for some sarcomas, including leiomyosarcomas)
- Requires a spindle cell component measuring at least one low power (40x) field
- May be discrete or intermixed with epithelial elements
- May be very focal
- Most common patterns are fibrosarcoma and malignant fibrous histiocytoma
- Rare cases reported with patterns of rhabdomyosarcoma, chondrosarcoma, osteosarcoma and hemangiopericytoma
- Pattern does not appear to affect prognosis
- Grade of sarcoma is not clinically significant
- May range from low to high
- Based on cellularity, atypia, mitotic figures
- May range from low to high
- See Classification/Lists in menu at left for links to specific carcinoma subtypes
John P Higgins MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting:: January 24, 2011