Pediatric Urologic Oncology
Core concepts
Know Wilms tumor (nephroblastoma) cold: peak age 3-4 years, often a painless abdominal mass, associated with WT1/WT2 alterations, Beckwith-Wiedemann, WAGR, and Denys-Drash syndromes. Staging drives therapy: NWTS/COG favors upfront nephrectomy for resectable unilateral disease, whereas SIOP uses preoperative chemotherapy. Bilateral Wilms and tumor in a solitary kidney get biopsy and chemotherapy first to preserve nephrons. Other tumors: clear cell sarcoma of kidney (bone metastases, worse prognosis), malignant rhabdoid tumor (young infants, brain mets, dismal), renal cell carcinoma (older children, associated with tuberous sclerosis), and multilocular cystic nephroma. Understand the role of nephron-sparing surgery, lymph node sampling, and loss-of-heterozygosity testing for risk stratification. Testicular tumors in children are usually yolk sac tumors (prepubertal, AFP marker) or mature teratomas; rhabdomyosarcoma of the bladder/prostate presents with urinary retention or hematuria.
Traps
- Assuming all abdominal masses in children are Wilms; neuroblastoma crosses the midline and calcifies, Wilms displaces the kidney.
- Forgetting that bilateral disease requires preservation of renal parenchyma.
- Confusing prepubertal (yolk sac/teratoma) with postpubertal (germ cell) testicular tumor patterns.
- Overlooking that hematuria in a child with a renal mass may signal tumor thrombus into the IVC.
Worked example
A 3-year-old with a smooth flank mass, normal AFP, and a renal mass that distorts calyces on CT most likely has Wilms tumor; management begins with staging imaging, then nephrectomy with lymph node sampling in COG protocols.
Rule of thumb
Age plus laterality plus markers narrows pediatric renal masses: young + unilateral = Wilms; older + tuberous sclerosis = RCC; infant + hypercalcemia = rhabdoid.