Clear cell sarcomas of the kidney (CCSK) are a rare mesenchymal renal tumor that account for ~5% of primary renal neoplasms in the pediatric population 1.
Clear cell sarcoma of the kidney is the second most common primary malignant pediatric renal neoplasm after Wilms tumor, with an annual incidence of 20 cases in the United States 2,3. The mean age of diagnosis is 3 years 2, although it is very rare before the age of 6 months 3,4. Males are noticed to be affected more with an M:F of 2:1 1.
Clear cell sarcoma of the kidney usually presents with a palpable abdominal mass; with hematuria and bone pain (in cases of metastatic disease) being less common.
The tumor appears as a large solid mass, usually unilateral and unifocal, replacing most of the kidney or centered in the medulla 1. The cut surface appears gelatinous due to the abundance of extracellular mucopolysaccharides. Hemorrhage and necrosis are frequent findings (70%) 2.
Histologically, nine subtypes have been described 1. Most of these, however, will show some of the classic features of the tumor microscopically, consisting of cords or nests of cells surrounded by delicate branching cellular fibrovascular septa akin to chicken wire.
Although the margins of the tumor appear well defined grossly, they demonstrate infiltration into adjacent renal parenchyma with entrapment of the tubules on high power field microscopy. The entrapped tubules may become extensively dilated, giving the apparent cysts seen on gross tumor inspection 2.
These tumors usually enhance heterogeneously and to a lesser extent than the adjacent kidney, with non-enhancing foci representing hemorrhage and necrosis 5. They often cross the midline. Calcification is uncommon 5.
Usually appears as:
- T1: low to intermediate signal
- T2: high signal with cystic areas
Treatment and prognosis
Clear cell sarcoma of the kidney has a worse prognosis compared to Wilms tumors, especially in those younger than 12 months of age 3. The mainstay treatment is radical nephrectomy with lymph node dissection. Relapse rate is high (20-40% of patients) 4.
Due to their rarity, there is no standard treatment for clear cell sarcoma of the kidney. Treatment may consist of surgical resection, chemotherapy, and/or radiotherapy 6.
The imaging appearances for clear cell sarcoma of the kidney are non-specific and can be very similar to other primary renal neoplasms, especially Wilms tumor which is much more common. Finding of bone metastasis could suggest clear cell sarcoma of the kidney rather than Wilms tumor 1.
- 1. Chung EM, Graeber AR, Conran RM. Renal Tumors of Childhood: Radiologic-Pathologic Correlation Part 1. The 1st Decade: From the Radiologic Pathology Archives. Radiographics. 2016;36 (2): 499-522. doi:10.1148/rg.2016150230 - Pubmed citation
- 2. Argani P, Perlman EJ, Breslow NE et-al. 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 citation
- 3. Furtwängler R, Gooskens SL, van Tinteren H et-al. Clear cell sarcomas of the kidney registered on International Society of Pediatric Oncology (SIOP) 93-01 and SIOP 2001 protocols: a report of the SIOP Renal Tumour Study Group. Eur. J. Cancer. 2013;49 (16): 3497-506. doi:10.1016/j.ejca.2013.06.036 - Pubmed citation
- 4. Gooskens SL, Furtwängler R, Vujanic GM et-al. Clear cell sarcoma of the kidney: a review. Eur. J. Cancer. 2012;48 (14): 2219-26. doi:10.1016/j.ejca.2012.04.009 - Pubmed citation
- 5. Glass RB, Davidson AJ, Fernbach SK. Clear cell sarcoma of the kidney: CT, sonographic, and pathologic correlation. Radiology. 1991;180 (3): 715-7. doi:10.1148/radiology.180.3.1871282 - Pubmed citation
- 6. PDQ Pediatric Treatment Editorial Board. Wilms Tumor and Other Childhood Kidney Tumors Treatment (PDQ®): Health Professional Version. 2018 Apr 2. In: PDQ Cancer Information Summaries [Internet]. Bethesda (MD): National Cancer Institute (US); 2002-. Available from: NCBI - PubmedK