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Diagnosis: Clear cell sarcoma of the kidney

Clear cell sarcoma of the kidney (CCSK) is an uncommon renal neoplasm of childhood with unfavorable prognosis and propensity to metastasize to bone.

The origin of clear cell sarcoma of the kidney has not been established. Dysregulation of the EGFR pathway has been observed at multiple levels in clear cell sarcoma of the kidney. The proto-oncogene c-kit is overexpressed in clear cell sarcoma of the kidney but is not accompanied by gene amplification or activating mutations. The t(10;17)(q22;p13) and deletion 14q have been described. Cells that have been suggested as the origin for clear cell sarcoma of the kidney include renomedullary interstitial cells, nonorgan specific mesenchymal cells, blastemal cap cells, primitive mesenchymal cells, and the cells that form the lower limbs of S-bodies. It has been also suggested that the cell of origin is within a renal mesenchymal cell that possesses neural markers.

Microscopically, several histological variants are described. The most common pattern is the classic pattern, which is present at least focally in over 90% of tumours. The classic subtype of CCSK is characterised by round/oval cells with clear cytoplasm, fairly uniform round/oval and often vesicular bland nuclei with finely dispersed chromatin, inconspicuous nucleoli and infrequent mitotic figures. Other histological patterns that have been described include myxoid (50%), sclerosing (35%), cellular (26%), epithelioid (13%), pallisading (11%), spindle-cell (7%), storiform (4%) and anaplastic (3%). In about 91% of the cases, more than one histological pattern is present. The differential diagnosis of CCSK primarily includes WT, congenital mesoblastic nephroma, malignant rhabdoid tumour of kidney, primitive neuroectodermal tumour, and also renal cell carcinoma. Immunohistochemistry of CCSK consistently shows non-specific positivity for vimentin. Recently, an analysis of 61 CCSK tumours demonstrated nerve growth factor receptor (NGFR) staining in all tested cases. CCSK is uniformly negative for cytokeratin, Mic-2, S100, neural markers, desmin and WT-1 (Gooskens SL, et al. Clear cell sarcoma of the kidney: A review. Eur J Cancer. 2012 May 12. [Epub ahead of print] [PubMed link])

In our case, the patient is well, without evidence of metastasis or recurrence (4 months after resection).

See the Chapter [Renal Neoplasms] of our Tutorial (currently there is only Spanish version of this chapter)

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References

• Gooskens SL, Furtwängler R, Vujanic GM, Dome JS, Graf N, van den Heuvel-Eibrink MM. Clear cell sarcoma of the kidney: A review. Eur J Cancer. 2012 May 12. [Epub ahead of print] [PubMed link]
• Lal N, Singhai A. Clear cell sarcoma of kidney: A rare entity. Indian J Med Paediatr Oncol. 2011;32(3):157-9. [PubMed link] [Free full text]
• Watts KE, Hansel DE, MacLennan GT. Clear cell sarcoma of the kidney. J Urol. 2011;185(1):279-80. [PubMed link]
• Hadley GP, Sheik-Gafoor MH. Clear cell sarcoma of the kidney in children: experience in a developing country. Pediatr Surg Int. 2010 Apr;26(4):345-8. [PubMed link]
• Portugal R, Barroca H. Clear cell sarcoma, cellular mesoblastic nephroma and metanephric adenoma: cytological features and differential diagnosis with Wilms tumour. Cytopathology. 2008 Apr;19(2):80-5 [PubMed link]
• Seibel N. Clear cell Sarcoma of the kidney. In: eMedicine: Link to the Website.
• Argani P, Perlman EJ, Breslow NE, Browning NG, Green DM, D'Angio GJ, Beckwith JB. Clear cell sarcoma of the kidney: a review of 351 cases from the National Wilms Tumor Study Group Pathology Center. Am J Surg Pathol. 2000;24(1):4-18. [PubMed link]

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