|Year : 2014 | Volume
| Issue : 4 | Page : 1104-1106
Clear cell sarcoma of the kidney: A case report
Dipanwita Nag1, Ayandip Nandi1, Palash Kumar Mandal2, Pranab Kumar Biswas1
1 Department of Pathology, Medical College, Kolkata, India
2 North Bengal Medical College, Siliguri, West Bengal, India
|Date of Web Publication||9-Jan-2015|
48/7, Patuapara Lane, P.O. Serampore, Hooghly District, Kolkata - 712 201, West Bengal
Source of Support: None, Conflict of Interest: None
Clear cell sarcoma of the kidney is a rare malignant neoplasm of childhood, known for its aggressiveness, its tendency for recurrence, and to metastasize to bone. We report the observation of 8-month-old child presenting with a large abdominal mass. Clinically, it was diagnosed as Wilm's tumor, and left nephrectomy was done. Grossly, 10 cm × 8 cm × 3.5 cm globular, white, encapsulated, smooth mass uniformly involving the whole kidney was noted. Histologically, the tumor was diagnosed as clear cell sarcoma with renal vein showing presence of tumor embolus in lumen. The tumor was given stage-II (NWTS-5 protocol). Immunohistochemistry showed vimentin positive and cytokeratin negative tumor cells. The child is currently undergoing chemotherapy and has not yet shown any sign of bony metastasis.
Keywords: Childhood renal neoplasms, clear cell sarcoma of kidney, immunohistochemical markers
|How to cite this article:|
Nag D, Nandi A, Mandal PK, Biswas PK. Clear cell sarcoma of the kidney: A case report. J Can Res Ther 2014;10:1104-6
| > Introduction|| |
Clear cell sarcoma of the kidney (CCSK) is a rare malignant renal neoplasm of childhood (4% of primary renal neoplasms), known for its aggressiveness, its tendency for recurrence, and to metastasize to bone. , Its peak incidence is in 3-5 years with slightly male (M: F = 2:1) preponderance. 
| > Case report|| |
A 8-month-old male child presented with gradually increasing abdominal lump for 3 months. There was no history of hematuria, vomiting, loss of weight. On examination, the patient had pallor, BP-85/35 mm Hg, no lymphadenopathy. A diffuse lump was felt in left loin, about 10 cm in diameter, firm to soft, non-tender, ballotable. His basic investigations revealed:
- CBC: Hb-11 g%, total leukocyte count: 4500/cmm, differential leucocyte count: N 56 L 36 M 8 , erythrocyte sedimentation rate-13 mm/1 st h
- Urine R/E: WNL
- Chest X-ray: No abnormality detected
- USG whole abdomen: Hypoechoic heterogeneous 10 cm× 8 cm × 3 cm lump uniformly involving left kidney. Liver, spleen, right kidney-WNL.
Abdominal computed tomography scan revealed [Figure 1] 10 × 8 × 2 cm heterogeneous mass involving left kidney. Renal vein and ureter were free. There was no paraaortic lymphadenopathy. Provisional diagnosis of Wilm's tumor was made by radiologist.
Left total nephrectomy was done and specimen was sent for histopathological examination. On gross examination [Figure 2], a globular encapsulated mass measuring 10 × 8 × 3.5 cm was seen. The cut section was greyish-white, homogeneous with whorled pattern and soft glistening areas at places. No hemorrhage, necrosis and variegated area were apparent on gross. Renal vein and ureter were grossly uninvolved. No lymph nodes were identified in the hilum.
Microscopy revealed monomorphous pattern of polygonal tumor cells [Figure 3] with clear vacuolated cytoplasm, round to oval nucleus with fine chromatin and indistinct nucleoli. Evenly distributed network of vascular septae connected by transverse arcades was characteristic in section. Mitotic count was low. Stump of renal vein showed presence of tumor emboli within the lumen [Figure 4]. Perinephric fat was free of tumor. Tumor was localized by a distinct capsule, and no infiltration was seen in adjacent renal parenchyma.
|Figure 3: Microscopic appearance of renal mass showing vascular arcades fibrous septae and clear monotonous tumor cells (H and E, ×400)|
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Immunohistochemistry showed strong positivity for vimentin [Figure 5] and negativity for cytokeratin [Figure 6]. Final diagnosis of CCSK with the invasion into the renal vein (stage II NWTS-5 protocol) was made. Patient is currently undergoing chemotherapy and has not yet shown any sign of metastasis.
| > Discussion|| |
Clear cell sarcoma is a highly aggressive tumor, metastasis to bone is reported in 17% of cases.  Marsden et al. called this tumor "bone metastasizing renal tumor of childhood."  5-year survival is 69%.  Hence, accurate and early diagnosis of clear cell sarcoma as a separate entity from Wilm's tumor is of extreme importance. Careful study of morphology; the characteristic delicate arborizing vascular septae, monomorphous population and invasive property will help to distinguish it from more common and less aggressive counterparts of childhood renal neoplasms like Wilm's tumor.  Points helpful in this matter are: Foci of blastema are not seen in clear-cell sarcoma; nonrenal elements such as cartilage or muscle are not found in clear cell sarcomas. Clear cell sarcomas are unilateral and unicentric, and sclerotic stroma is uncommon in Wilms tumor before therapy. The vascular pattern typical of clear cell sarcoma is often helpful in distinguishing it from Wilms tumor. The border with the kidney is usually infiltrative in CCSK, whereas the border of Wilms tumor is typically "pushing." Histological variants of CCSK include spindle cell, sclerosing, epithelioid, myxoid, pallisading, storiform and anaplastic clear cell sarcoma.  Epithelial variety of CCSK mimics wilm's tumor, which can be differentiated by immunohistochemistry.  Combined chemotherapeutic approach with doxorubicin, vincristine, cyclophosphamide, etoposide has been proved very effective in reducing recurrence and metastasis. 
| > Conclusion|| |
Early diagnosis of clear cell sarcoma is of utmost importance because of its aggressive nature. Many variants of CCSK makes it difficult to distinguish this from more common, but less aggressive childhood renal neoplasms like wilm's tumor.
| > References|| |
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]