4.3 Wilms Tumor and Other Renal Tumors
Key Takeaways
- Wilms tumor peaks around 3–4 years as a painless abdominal mass; limit repeated palpation because of preoperative rupture and upstaging risk.
- Predisposition syndromes WAGR, Beckwith-Wiedemann, and Denys-Drash drive serial abdominal ultrasound screening rather than waiting for a visible mass.
- U.S. COG-style care typically uses upfront nephrectomy when feasible; SIOP protocols use neoadjuvant chemotherapy before surgery.
- Favorable versus anaplastic histology and stages I–V (V is bilateral), plus lung metastases, drive vincristine, dactinomycin, doxorubicin, and radiation for higher-stage or ruptured disease.
- Clear cell sarcoma seeds bone, rhabdoid tumor is a young-child aggressive disease that warrants brain imaging, and congenital mesoblastic nephroma is an infant tumor often cured with surgery. Hypertension, residual renal function, and anthracycline cardiac surveillance are long-term nursing priorities.
Wilms tumor (nephroblastoma) is the most common primary renal malignancy of childhood. Peak age is about 3 to 4 years. The classic presentation is a painless abdominal mass noticed in the bath or by a relative who has not seen the child for a month. Hematuria, fever, and hypertension from renin-mediated compression of the renal vasculature are common companions. CPHON items punish two errors: treating the belly like a physical-diagnosis toy, and treating every pediatric renal mass as if it were favorable-histology Wilms.
Do not palpate the tumor into a higher stage
Repeated deep palpation risks preoperative rupture and peritoneal spillage, which upstages disease and can add radiation. One careful exam to confirm a mass is enough. After that, imaging—not shift-by-shift bimanual exams—tracks size. Teach students and families: hands off the flank. Preoperative rupture can also occur spontaneously or at surgery; document any abdominal trauma and handle transfers with the same caution you would use for a full bladder of chemotherapy.
A 3-year-old with a firm, nontender, unilateral flank mass, mild hypertension, and microscopic hematuria is Wilms until imaging and histology say otherwise. Do not order a trial of massage to shrink the mass, and do not let every learner on the team recheck the size.
Syndromes that change screening, not just trivia
Three predisposition syndromes belong in active nursing memory because they change screening:
- WAGR syndrome: Wilms tumor, Aniridia, Genitourinary anomalies, and Range of developmental delay—a contiguous-gene deletion involving WT1 and PAX6. Absent iris is the physical clue in clinic.
- Beckwith-Wiedemann syndrome: overgrowth, macroglossia, omphalocele or umbilical hernia, hemihypertrophy, and elevated risk of Wilms tumor and hepatoblastoma. Serial abdominal ultrasound (and often serum alpha-fetoprotein for hepatoblastoma in early years) is the screening principle—do not wait for a visible mass.
- Denys-Drash syndrome: WT1-related nephropathy (diffuse mesangial sclerosis and early renal failure), 46,XY gonadal dysgenesis or ambiguous genitalia, and a high Wilms risk.
Screening principle: children with these diagnoses, and isolated hemihypertrophy in many programs, receive periodic abdominal ultrasound on a schedule set by the genetics and oncology teams, commonly every 3 months in early childhood. Teach families that a normal last scan does not make the next one optional. After a Wilms diagnosis, still look backward for aniridia, hemihypertrophy, and nephropathy—the contralateral kidney may be at risk.
| Syndrome | Clinical clues | Screening implication |
|---|---|---|
| WAGR | Aniridia, genitourinary anomalies, developmental delay | Serial abdominal ultrasound; genitourinary and developmental care |
| Beckwith-Wiedemann | Macroglossia, omphalocele, hemihypertrophy | Serial abdominal ultrasound; alpha-fetoprotein as the program specifies |
| Denys-Drash | Early nephropathy, ambiguous genitalia | High Wilms risk; renal-failure planning |
| Isolated hemihypertrophy | Asymmetric growth | Many programs still ultrasound-screen in early childhood |
Histology, stage, and two philosophies of timing
Favorable histology (triphasic blastema, epithelium, and stroma, without anaplasia) is the common, more chemosensitive group. Anaplastic (unfavorable) histology changes intensity and radiation decisions. Staging in Children’s Oncology Group (COG) practice is surgical-pathologic:
- Stage I: tumor confined to the kidney, completely resected.
- Stage II: extends beyond the kidney but completely resected.
- Stage III: residual tumor, positive lymph nodes, rupture or spillage, or incomplete resection.
- Stage IV: hematogenous metastases; lung is the most common site.
- Stage V: bilateral renal involvement at diagnosis.
COG versus SIOP is a philosophy question, not a morality question. COG-style care in the United States typically performs upfront nephrectomy when feasible, then assigns adjuvant therapy from true pathologic stage and histology. International Society of Paediatric Oncology (SIOP) protocols, widely used in Europe, give neoadjuvant chemotherapy first, then surgery, which can shrink tumors and reduce rupture risk but means preoperative stage is imaging-based. Neither approach is wrong; CPHON expects you to know that U.S. practice is usually COG/upfront surgery when the tumor is resectable, and that inoperable, extensive, or bilateral disease may still receive preoperative chemotherapy even in COG settings. Do not tell a family that SIOP is illegal in North America or that every U.S. child must get 6 weeks of chemotherapy before the operating room.
Bilateral (stage V) disease is a kidney-sparing problem: the goal is tumor control and residual nephrons. Nephron-sparing surgery after chemotherapy is common. Lung nodules, when they represent metastases, add pulmonary-directed therapy—chemotherapy intensity and, in selected cases, lung radiation—per protocol.
Drugs, radiation, and other renal tumors that are not Wilms
Backbone agents are vincristine and dactinomycin. Doxorubicin is added for higher-stage or unfavorable disease. Radiation is used for higher stage, rupture or spillage, residual disease, and selected metastatic sites—not for every completely resected stage I favorable tumor. Vincristine brings constipation and neuropathy; dactinomycin can cause hepatopathy (a veno-occlusive-like illness), especially when combined with radiation; doxorubicin requires long-term cardiac surveillance with echocardiography because anthracycline cardiomyopathy can appear years later.
Not every pediatric renal mass is Wilms:
- Clear cell sarcoma of the kidney has a reputation for bone metastases; bone scan belongs in the workup. It is treated more intensively than favorable Wilms.
- Rhabdoid tumor of the kidney strikes very young infants and toddlers, is highly aggressive, and is associated with CNS rhabdoid tumors (atypical teratoid/rhabdoid tumor biology). Brain MRI is part of staging.
- Congenital mesoblastic nephroma is a tumor of infants, often in the first months of life, and is frequently cured with surgery alone.
A 3-week-old with a renal mass is mesoblastic nephroma until proven otherwise; a 10-month-old with a viciously aggressive renal tumor and a brain lesion is rhabdoid until proven otherwise; a 3-year-old with a painless flank mass is Wilms until proven otherwise.
Hypertension, the remaining kidney, and survivorship
Treat hypertension; do not ignore it as pain. After unilateral nephrectomy, residual renal function is a lifelong nursing topic: avoid nephrotoxic habits, treat urinary infections, watch blood pressure, and caution with contact sports and nonsteroidal anti-inflammatory overuse as the child grows. Families need a sick-day plan that does not assume two spare kidneys. If doxorubicin was given, schedule echocardiographic follow-up even when the child looks fine. Pulmonary radiation, when used, adds lung and breast-field late-effect counseling in girls.
The CPHON picture is a preschooler with a bath-time mass, a please-do-not-poke-this-belly sign on the door, a WAGR or Beckwith screening ultrasound that found a lesion before it was visible, a COG-style trip to the operating room, vincristine–dactinomycin with or without doxorubicin, and a survivorship folder that includes the remaining kidney and the heart.
A 3-year-old arrives with a painless, firm, unilateral abdominal mass. Several residents want to recheck the size by deep palpation each shift. What is the correct nursing action?
A family who read European blogs asks why their 4-year-old with a resectable unilateral Wilms tumor is going to the operating room before chemotherapy. Which explanation is accurate for typical U.S. cooperative-group practice?
An 8-month-old has a rapidly enlarging renal mass, hypertension, and hypercalcemia. Staging MRI of the brain is ordered. Which tumor biology best explains that imaging choice?