Congenital mesoblastic nephroma: Clinical analysis of eight cases and a review of the literature.

Congenital mesoblastic nephroma (CMN) is a mesenchymal renal tumor. The aim of the present study was to review the clinical characteristics and outcome of CMN in infants. A retrospective file review was conducted of eight cases of CMN treated at the Children's Hospital of Fudan University between 2004 and 2012. Ultrasound and computerized tomography scans had been performed on all eight patients. Two cases presented with a solid tumor and exhibited pathological features consistent with those of classic CMN, five cases exhibited cystic, hemorrhagic and necrotic characteristics, with calcification and pathology consistent with the cellular variant of CMN and one case presented with a solid tumor, which exhibited pathological features consistent with ceullular CMN. Histology confirmed classic CMN in two patients and cellular CMN in six patients. For surgical intervention, four cases had radical nephrectomy, one case had a half nephrectomy and three cases had tumor enucleation performed. Two cases had received pre-operative chemotherapy, but exhibited no response, and three cases received post-operative chemotherapy. Two patients were lost to follow-up, but the remaining six patients survived to the end of follow-up without further complications. The mean follow-up time was 24.6 months. In conclusion, the differential diagnosis between CMN and Wilms' tumor is critical. Imaging characteristics are partially correlated with pathological characteristics. Surgery is the main treatment for CMN, but pre-operative chemotherapy is not particularly effective. The efficacy of post-operative chemotherapy requires further investigation, but the prognosis is positive.