Fdg Pet/Ct Studies of Children with Non-Wilms Renal Tumors

1707 Objectives 1. To determine the metabolic activity of non-Wilms renal tumors in children. 2. Assess potential utility of FDG PET/CT in managing patients with these very rare tumors. Methods 15 pts with non-Wilms renal tumors underwent FDG PET/CT (total 54) scans. 13 ♂, 2 ♀; age at diagnosis (dx) 4 months to 17 years. Diagnoses ( # pts, # scans): Rhabdoid sarcoma (5, 27), renal cell carcinoma (3, 6), undifferentiated sarcoma (3, 3), clear cell sarcoma (2, 4), transitional cell carcinoma (1, 7), and renal medullary carcinoma (1, 7). Results Rhabdoid sarcoma: 1 scan at dx and 26 during followup. Each pt had at least 1 abnormal study indicating tumor. 4 of the 5 pts died of disease. 1 pt whose studies became negative during treatment has been free of disease for 3 years. Renal cell carcinoma: 1 study done at dx showed no uptake within the renal tumor. In a 2nd pt, 2 scans showed recurrent disease. In a 3rd pt, 3 scans showed uptake within pulmonary nodules. Disease has been stable for 8 years. Undifferentiated sarcoma: All scans performed to assess for recurrent disease. 1 showed uptake in pulmonary nodules. 1 pt studied postoperatively and a 2nd pt 4 years after treatment had no areas of abnormal uptake. Clear cell sarcoma: One pt studied post nephrectomy had a negative study. During followup he developed brain metastases which showed only slight uptake compared to white matter. These were excised and he remains free of disease 5 years later. Another pt had 2 studies done after treatment, both negative. Renal medullary carcinoma: A pt was studied before resection and multiple times during therapy. Scans were positive in the tumor bed and in the lungs. Transitional cell carcinoma: 1 pt was studied x 7 for recurrent disease, all scans abnormal indicating tumor. Conclusions Most non-Wilms renal tumors in childhood are metabolically active. FDG PET CT is useful in the management of these patients, particularly in determining the response to therapy. As in adults, renal cell carcinomas may not be metabolically active.