Wilms' tumour (nephroblastoma) is the most common intrarenal malignancy of childhood. The most common presentation is of an asymptomatic abdominal mass (more than 80%), usually discovered incidentally. Abdominal pain occurs in 30% to 40% of patients, and hypertension, frank haematuria and fever are found in 5% to 30%. A lesser known presentation of Wilms' tumour is that of acquired von Willebrand syndrome (AVWS). This has a well recognised association with malignancies, most commonly with monoclonal gammopathies, lymphoproliferative and myeloproliferative disorders, and less commonly with solid tumours. In this article we report two cases of AVWS in patients with Wilms' tumour, the discovery of which led to a retrospective study to determine the incidence of acquired von Willebrand syndrome and coagulopathy in general in association with Wilms' tumour. We reviewed the case notes of 65 children diagnosed with Wilms' tumour between 1996 and 2001 and referred to a haematology/oncology unit within a tertiary referral centre. We observed an incidence of abnormal clotting in 16/65 and AVWS in 2/65. Treatment of the coagulation abnormalities in these two patients was with fresh frozen plasma for both and also von Willebrand factor concentrate for one. In both cases resolution of the coagulation abnormalities occurred upon treatment of the tumour.Conclusion:
we emphasise the importance of a routine coagulation screen in every patient who presents with a possible Wilms' tumour.