–Age of mother: mean age 34 years (unilateral: 28 years of age)

–Association with other malformations: 45% (unilateral: 4%)

11.14.1.1 Therapy

•Individual procedure

•Unilateral nephrectomy, partial resection of the contralateral kidney, or bilateral partial resection

•Preoperative chemotherapy, eventually in combination with radiotherapy

•Bilateral resection of both kidneys followed by renal transplantation after chemotherapy

•Radiotherapy with low-dose irradiation: 10–20 Gy

11.14.1.2 Prognosis

•70%, but with high risk of renal failure due to aggressive treatment or persistent/ recurrent kidney tumors

11.14.2Congenital Mesoblastic Nephroblastoma (Fetal Renal Hamartoma)

•Frequency: More than 80% of neonatal nephroblastomas and 50% of nephroblastoma in infancy (fibromatous variant)

•Potential malignant cellular variants in infants and small children

11.14.2.1 Pathology

• Mostly marked kidney enlargement, with bundles of spindle cells and frequent mitoses

11.14.2.2 Clinical Manifestations

• Mostly large abdominal tumor masses in children after birth until 1 year of age

• Staging according to Wilms tumor (see above)

• Rarely hyperreninemia with hypertension, secondary aldosteronism, and high serum level of renin

11.14.2.3 Therapy

•Nephrectomy

•After incomplete resection, occasionally tumor relapses

•Where there is suspicion of malignant histology or after subtotal resection, therapy as in nephroblastoma

11.14.3 Renal Cell Carcinoma

•Frequent renal tumor in adulthood

•One to two percent mostly in children over the age of 5 years

•Possible abnormality of chromosome 3