Accuracy of diagnostic imaging in nephroblastoma before preoperative chemotherapy

The main strategy in the treatment of nephroblastoma, as described in protocol SIOP 9/GPO, is preoperative chemotherapy for patients between 6 months and 16 years of age. Before treatment the diagnosis is made only by diagnostic imaging without biopsy. From July 1988 to February 1991, 130 children with the tentative diagnosis of nephroblastoma were treated preoperatively. The initial diagnostic images (excretory urography, ultrasound, CT, MRI) have been analysed both prospectively and retrosperatively and the findings correlated with the intraoperative and histological results. Of the preoperatively treated patients 93.8% had a Wilms' tumour or one of its variants. Five patients had a different malignant tumour and 3 patients, i.e. 2.3% of those preoperatively treated or 1.6% of all registered patients, had benign tumours of the kidney. Wilms' tumour generally presented as a well-defined mass with an inhomogeneous morphology on CT. On ultrasound only 24% of the tumours were homogeneous. Intratumoral haemorrhage and cystic areas occurred frequently; calcifications were rare (8%). With regard to caval involvement only ultrasound and MRI enabled the correct diagnosis, while CT could not differentiate compressions from invasion. The pretherapeutic diagnostic imaging was of sufficient accuracy to start preoperative chemotherapy without diagnostic biopsy.Correspondence to: K. Rieden