Purpose: Conservative management of children who have unequivocal multicystic dysplastic kidney with a stable or regressive pattern of disease during close followup is well established. However, a clear diagnosis may prove difficult. We report 3 cases in which the diagnosis was particularly difficult to increase awareness of the importance of applying strict criteria for the diagnosis of multicystic dysplastic kidney.
Materials and methods: Three children in whom a diagnosis of multicystic dysplastic kidney was suspected underwent surgical exploration. One patient who did not comply with followup presented with a large retroperitoneal mass suspicious for neuroblastoma 8 months later. In another patient a growing renal cystic mass was suspicious for a multilocular cyst at 3 months of followup. At 2 months of followup a cystic nephroma was suspected in the remaining patient.
Results: All patients underwent surgical exploration. The patient with suspected neuroblastoma had extensive stage 3 Wilms tumor. In the child with a suspected multilocular cyst segmental multicystic dysplastic kidney of the lower pole of an ipsilateral duplicated system was found. In the patient in whom cystic nephroma was suspected mesoblastic nephroma was confirmed by the National Wilms Tumor Study Pathology Center.
Conclusions: An unequivocal diagnosis of multicystic dysplastic kidney should be made early in life. The urologist should have an active role in making the initial radiological diagnosis and close followup with renal ultrasound every 3 to 4 months is essential during year 1 of life. Surgical exploration is indicated if the diagnosis becomes equivocal at any point or should concerns exist regarding compliance with followup.