ABSTRACT: Clear cell sarcoma of the kidney (CSSK), also known as bone metastasizing renal tumor of childhood, is an uncommon malignant renal neoplasm characterized by undifferentiated mesenchymal cells. It has a wide histologic spectrum and often mimics other pediatric renal tumors (ie. Wilms’ tumor) resulting in considerable diagnostic difficulty.  This case report will present a case of a one-year old male who initially presented with abdominal mass associated with passage of tea colored urine of ten weeks duration with initial clinical diagnosis of Wilms’ tumor.  Histopathologic analysis of renal tissues turned out to be clear cell sarcoma of the kidney.
  
OBJECTIVE: This case report aims to discuss a rare case of abdominal mass mimicking other types of renal neoplasm and its case management.

CASE: Patient is a one-year old male, Filipino, from Batangas, overweight at 12.4kg who presented abdominal enlargement of 10 weeks duration. He initially presented with tea colored urine associated with fever and abdominal pain.  Upon admission, patient was noted to have hypertensive episodes which responded with propranolol and Nifedipine.  Patient underwent exploratory laparotomy, left radical nephrectomy and paraaortic lymph node sampling. Histopathology result was consistent with clear cell sarcoma, Stage I. He was then started adjunct chemotherapy with Vincristine, Doxorubicin, Etoposide and Cyclophosphamide with noted improvement during chemotherapy. 
  

CONCLUSION: Clinical manifestations of CCSK may mimic other types of renal tumors such as Wilms tumor which may lead to diagnostic difficulty. Further research is needed to improve methods of diagnosis. Tissue sampling should undergo evaluation by knowledgeable pathologists familiar with subtleties between pediatric renal neoplasms, although immunohistochemistry with Vimentin might be helpful to distinguish CCSK from other renal tumors. Treatment usually comprises of nephrectomy followed by adjuvant chemotherapy such as Doxorubicin in combination with Vincristine and Dactinomycin.