Clear Cell Sarcoma of the Kidney Mimicking Wilms Tumor in a Child

Abstract

Abstract Background: Clear cell sarcoma of the kidney (CCSK) is a rare malignant renal tumor in children, the diagnosis of which is a challenge due to nonspecific clinical and radiological presentation. Clinical Description: A 4-year-old boy presented with a 2-day history of abdominal pain and hematuria, without oliguria, pallor, or hypertension. His renal function was within the normal limits. An initial ultrasound of the abdomen showed an iso- to hyperechoic lesion in the mid pole of the right kidney causing compression of the pelvicalyceal system. A computed tomography scan revealed a relatively heterogenous hypoenhancing mass lesion with a “claw sign” suggestive of solid renal neoplasm with doubtful infiltration of quadratus lumborum and psoas muscle, most probably Wilms tumor. Management and Outcome: The child was started on neoadjuvant chemotherapy with vincristine, actinomycin D, and doxorubicin according to the National Wilms Tumor Study protocol (NWTS) suspecting stage III Wilms tumor. After six cycles, surgical resection of the tumor was done, which on histopathological examination, was consistent with CSSK. The child received postoperative flank irradiation. Chemotherapy was escalated to Regimen I (vincristine, doxorubicin, cyclophosphamide, and etoposide) for 24 weeks. The child improved and was free of metastasis till the last follow-up. Conclusion: Before a renal tumor is labeled as Wilms tumor, all efforts must be made to rule out the more sinister, but similar appearing CCSK, so that an effective and aggressive treatment regimen can be administered timely.