[Diagnostic value of imaging procedures in nephroblastoma before preoperative chemotherapy: initial results]

According to the international SIOP 9 study preoperative chemotherapy for patients between 6 months and 16 years old is a major component of the therapeutic management of Wilms' tumour. Prior to treatment, the diagnosis is established by diagnostic imaging alone, without biopsy. This study was therefore undertaken to verify the accuracy of diagnostic imaging in the German GPO study group. Between July 1988 and November 1990, 156 patients with known histology were registered in the study centre. Of these patients, 67% (105/156) received preoperative chemotherapy. The diagnosis was initially established by US, TVP and CT, and in some cases MRT without prior biopsy. Of these preoperatively treated patients, 92.4% (97/105) had Wilms' tumour or one of its variants. Five patients had a different malignant tumour. Three cases, i.e. 2.8% of the preoperatively treated patients or 1.9% of all registered patients with known histology, had benign tumours of the kidney. Morphologically, the Wilms' tumour was revealed by a characteristic inhomogeneity in sonography and the CT scan. The inhomogeneity in the CT scan increased following injection of contrast medium. Intratumoral bleeding and cystic areas were observed frequently in the native scan. Calcifications were seen in 5% of the cases. The predictive value of pretherapeutic diagnostic imaging was good enough to justify instituting chemotherapy without diagnostic biopsy. It is still difficult in diagnostic imaging to differentiate the very rare benign cystic nephroma from malignant nephroblastoma. Intravenous pyelography proved to be the best method for distinguishing extrarenal from renal tumours.