[Clear cell sarcoma of the kidney. A study of 13 cases]

Clear cell sarcoma of the kidney (CCSK) also called a "bone-metastasizing renal tumor of childhood" is the second common pediatric renal neoplasm. This tumor is associated with a higher rate of relapse and a wider distribution of metastases than Wilms' tumor.

We have reviewed records of 13 cases of CCSK among 277 renal tumors (5%) diagnosed at the children's hospital of Rabat between 1990 and 2002.

The median age at diagnosis was 14 months (5 months-9 years). The male to female ratio was 5.5:1.00. Abdominal mass, usually the first physical finding, was associated with hematuria in four cases. No congenital malformation syndrome or familial Wilms' tumor were observed. Imaging studies found out seven right and six left intrarenal processes. Preoperative chemotherapy was given according to the SIOP9, SIOP93-01 and GFAOP 98 protocols. Twelve of 13 children underwent nephrectomy. Tumor measurements varied through 450-3450 g and 7-26 cm. The classic morphologic pattern was seen in nine cases (69%). The distribution local stage was I: three cases; II: three cases; III: six cases; IV: one case. Postoperative chemotherapy and radiotherapy (21 600-30 600 cGy) was done in 10 cases. With a median follow up of 44 months, four patients showed bone metastases (31%), four are alive in CR, four are lost for follow up and five died.

CCSK remains the pediatric renal tumor most frequently misdiagnosed. Its aggressiveness and its ability to give bone metastases need to recognize early this diagnosis for an adapted treatment.