Clear cell sarcoma of the kidney: a clinicopathologic study of 21 patients with long-term follow-up evaluation.

The clinical and pathologic features of 21 children with clear cell sarcoma of the kidney are presented. These cases were identified among 517 primary renal tumors collected from four pediatric institutions. Abdominal mass and hematuria were the usual presenting signs. The male to female ratio was 1.3 to 1. Although the mean age at diagnosis was 3 years, the sarcomas were diagnosed earlier in boys (2 years, 7 months) than in girls (3 years, 7 months). Tumor size and weight may have accounted for this difference, since the average tumor weights were 899 g for boys and 635 g for girls. Right kidney locations predominated (14 cases). The most common site for metastasis was the skeleton (12 patients), and the skull was almost invariably involved (10 children). Bone metastases preceded the development of metastases elsewhere in nine patients, in five of whom the involvement was polyostotic. Of the 12 patients with osseous metastases, nine died within five years of diagnosis, and one died eight years and nine months after diagnosis; the remaining two patients were successfully treated with a combination of surgery, radiotherapy, and actinomycin D, vincristine, cyclophosphamide, and Adriamycin. Eight of the nine patients with lung metastases died within five years of diagnosis. Until substantial proof is found that clear cell sarcoma of the kidney is related to nephroblastoma, its identification as a non-Wilms' sarcoma would seem to be appropriate. This tumor is not the only sarcoma of the kidney, but it appears to be the most common renal sarcoma of childhood.