The role of biopsy in the diagnosis of renal tumors of childhood: Results of the UKCCSG Wilms tumor study 3

BACKGROUND: The United Kingdom Children's Cancer Study Group (UKCCSG) Wilms Tumor Study 3 has adopted preoperative chemotherapy for Wilms tumors (WT), but required prechemotherapy biopsy for histologic diagnosis. The aims of this review were to assess the usefulness and safety of prechemotherapy biopsy and to compare histologic features of WT before and after chemotherapy. PROCEDURE: There were 286 eligible patients but only 241 biopsies and 226 nephrectomy case slides were submitted for panel review. The presence of different histologic components of WT before and after chemo therapy was retrospectively assessed. RESULTS: Among the 241 cases, the biopsy material in 9 (4%) was not diagnostic, in 28 (12%) that were clinically and radiologically consistent with WT, the biopsy revealed tumors other than WT, and in the remaining 204 (85%) WT was confirmed. Of 188 WT suitable cases, blastema was found in 89% of tumors at biopsy, but in only 50% at nephrectomy; the remainder were either completely necrotic (17%) or showed only epithelial and/or stromal elements (33%). Of 182 children who had percutaneous cutting needle biopsy (PCNB), a fall in haemoglobin (20% of cases) and local pain (19%) were the most common complications. One child required emergency nephrectomy due to massive intratumoral bleeding, another had tumor rupture and subsequently died, and a third developed a needle track recurrence 8 months after the biopsy. CONCLUSIONS: A number of renal tumors (12%) can have the correct histologic diagnosis made by PCNB. Preoperative chemo therapy markedly decrease in the number of samples with preserved blastema. The morbidity associated with PCNB is small. Needle biopsy of any renal mass prior to initiation of chemotherapy is recommended.