- 1 in 200,000 births.
- Mesoblastic nephroma (renal hamartoma) is the most frequent renal tumor, while Wilms’ tumor (nephroblastoma) is extremely rare.
- In both tumors there is a solitary mass replacing the normal architecture of the whole or part of the kidney.
- Cystic areas may appear due to hemorrhagic necrosis.
- In most cases, there is associated polyhydramnios.
- The incidence of chromosomal abnormalities is not increased.
- Nephroblastoma can be associated with the Beckwith–Wiedemann syndrome with evidence of organomegaly and macroglossia.
- Detailed ultrasound examination.
- Ultrasound scans every 2-3 weeks to monitor the size of the tumor and development of heart failure and polyhydramnios.
- Place: hospital with facilities for neonatal intensive care. In about 20% of neonates there is hypertension due to overproduction of renin by the affected or normal kidney.
- Method: vaginal delivery.
- Mesoblastic nephromas are benign, and nephrectomy is curative in the majority of cases. In a few cases there is local recurrence or distant metastases in the first year of life.
- Wilms’ tumor is malignant and about 50% are associated with genetic syndromes (such as Beckwith– Wiedemann syndrome). Treatment of the tumor requires nephrectomy, chemotherapy and sometimes radiotherapy; Survival is >90%.
- Mesoblastic nephroma: no increased risk of recurrence.
- In nephroblastoma associated with Beckwith–Wiedemann syndrome (autosomal dominant) the risk is increased.