Clear cell sarcoma of the kidney

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Clear cell sarcoma (CCS) is a rare mesenchymal tumour that accounts for 4-5% of primary renal neoplasms in paediatric population ¹.

Epidemiology

CCS is the second most common primary malignant renal neoplasm after Wilms tumour, with an annual incidence of 20 cases in the United States ^2,3. The mean age of diagnosis is 3 years ², although it's very rare before the age of 6 months ^3,4. Males are noticed to be affected more with a male to female ratio of 2:1 ¹.

Clinical presentation

CCS usually presents with a palpable abdominal mass; with hematuria and bone pain being less common.

Pathology

CCS appears as a large solid mass, usually unilateral and unifocal, replacing most of the kidney or centred in the medulla ¹. The cut surface appears gelatinous due to abundance of extracellular mucopolysaccharides. Hemorrhage and necrosis are frequent finding (70%) ².

Histologically, 9 subtypes have been described ¹. Most of these, however, will show some of the classic features of the tumour microscopically, consisting of cords or nests of cells surrounded by delicate branching cellular fibrovascular septa akin of chicken wire.

Although the margins of the tumour appear well defined grossly, they demonstrate infiltration in to 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 tumour inspection ².

Radiographic features

CT

These tumours usually enhance heterogenously and to a lesser extent than the adjacent kideny, with non enhancing foci representing hemorrhage and necrosis ⁵. They often cross the midline. Calcification is uncommon ⁵.

MRI

CCS usually appears low to intermediate on T1 weighted images and high signal on T2WI with cystic areas.

Treatment and prognosis

CCS has worse prognosis compared to Wilms, 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.

-<p><strong>Clear cell sarcoma (CCS)</strong> is a rare mesenchymal tumour that accounts for 4-5% of primary renal neoplasms in paediatric population <sup>1</sup>. </p><h4>Epidemiology</h4><p>CCS is the second most common primary malignant renal neoplasm after Wilms tumour, with an annual incidence of 20 cases in the United States <sup>2,3</sup>. The mean age of diagnosis is 3 years <sup>2</sup>, although it's very rare before the age of 6 months <sup>3,4</sup>. Males are noticed to be affected more with a male to female ratio of 2:1 <sup>1</sup>. </p><h4>Clinical presentation </h4><p>CCS usually presents with a palpable abdominal mass; with hematuria and bone pain being less common. </p><h4>Pathology</h4><p>CCS appears as a large solid mass, usually unilateral and unifocal, replacing most of the kidney or centred in the medulla <sup>1</sup>. The cut surface appears gelatinous due to abundance of extracellular mucopolysaccharides. Hemorrhage and necrosis are frequent finding (70%) <sup>2</sup>. </p><p>Histologically, 9 subtypes have been described <sup>1</sup>, </p>
+<p><strong>Clear cell sarcoma (CCS)</strong> is a rare mesenchymal tumour that accounts for 4-5% of primary renal neoplasms in paediatric population <sup>1</sup>. </p><h4>Epidemiology</h4><p>CCS is the second most common primary malignant renal neoplasm after Wilms tumour, with an annual incidence of 20 cases in the United States <sup>2,3</sup>. The mean age of diagnosis is 3 years <sup>2</sup>, although it's very rare before the age of 6 months <sup>3,4</sup>. Males are noticed to be affected more with a male to female ratio of 2:1 <sup>1</sup>. </p><h4>Clinical presentation</h4><p>CCS usually presents with a palpable abdominal mass; with hematuria and bone pain being less common. </p><h4>Pathology</h4><p>CCS appears as a large solid mass, usually unilateral and unifocal, replacing most of the kidney or centred in the medulla <sup>1</sup>. The cut surface appears gelatinous due to abundance of extracellular mucopolysaccharides. Hemorrhage and necrosis are frequent finding (70%) <sup>2</sup>. </p><p>Histologically, 9 subtypes have been described <sup>1</sup>. Most of these, however, will show some of the classic features of the tumour microscopically, consisting of cords or nests of cells surrounded by delicate branching cellular fibrovascular septa akin of chicken wire. </p><p>Although the margins of the tumour appear well defined grossly, they demonstrate infiltration in to 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 tumour inspection <sup>2</sup>. </p><h4>Radiographic features</h4><h5>CT</h5><p>These tumours usually enhance heterogenously and to a lesser extent than the adjacent kideny, with non enhancing foci representing hemorrhage and necrosis <sup>5</sup>. They often cross the midline. Calcification is uncommon <sup>5</sup>. </p><h5>MRI</h5><p>CCS usually appears low to intermediate on T1 weighted images and high signal on T2WI with cystic areas. </p><h4>Treatment and prognosis</h4><p>CCS has worse prognosis compared to Wilms, especially in those younger than 12 months of age <sup>3</sup>. The mainstay treatment is radical nephrectomy with lymph node dissection. Relapse rate is high (20-40% of patients) <sup>4</sup>. </p>

References changed:

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. <a href="http://dx.doi.org/10.1016/j.ejca.2012.04.009">doi:10.1016/j.ejca.2012.04.009</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/22579455">Pubmed citation</a><span class="auto"></span>
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. <a href="http://www.ncbi.nlm.nih.gov/pubmed/10632483">Pubmed citation</a><span class="auto"></span>
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. <a href="http://dx.doi.org/10.1016/j.ejca.2013.06.036">doi:10.1016/j.ejca.2013.06.036</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/23880476">Pubmed citation</a><span class="auto"></span>
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. <a href="http://dx.doi.org/10.1148/rg.2016150230">doi:10.1148/rg.2016150230</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/26963460">Pubmed citation</a><span class="auto"></span>
5. Glass RB, Davidson AJ, Fernbach SK. Clear cell sarcoma of the kidney: CT, sonographic, and pathologic correlation. Radiology. 1991;180 (3): 715-7. <a href="http://dx.doi.org/10.1148/radiology.180.3.1871282">doi:10.1148/radiology.180.3.1871282</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/1871282">Pubmed citation</a><span class="auto"></span>

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