Renal tumors account for approximately 6% of all childhood malignancies, with Wilms tumor (nephroblastoma) representing roughly 80–85% of cases. It is not until approximately age 15 years and older that renal cell carcinoma (RCC) becomes the dominant renal malignancy. Approximately 15–20% of pediatric renal tumors are something other than Wilms tumor, and recognition of these entities is critical for appropriate management. While many surgical principles are shared across tumor types, key biologic and therapeutic differences exist. A comparative summary is provided in the table below.Importantly, imaging cannot reliably distinguish Wilms tumor from other renal tumors (including congenital mesoblastic nephroma and rhabdoid tumor), and caution is warranted when initiating treatment without histologic confirmation, particularly in infants and in atypical presentations. Paraneoplastic syndromes can occur with any pediatric renal tumor and are not pathognomonic. A brief comparison of these tumors is provided in the table below.
Tumor | Average age at diagnosis | Prevalence of pediatric renal tumors | Unique presenting symptoms | Unique additional diagnostic workup* | Syndrome / Genetics | Important features |
three years (range zero years to adult) | 80-85% | painless abdominal mass | Beckwith-Wiedemann syndrome WAGR syndrome Denys-Drash syndrome Frasier syndrome Li-Fraumeni syndrome WT1 gene mutation1 q gain: adverse prognostic biomarker | Upfront radical nephroureterectomy with lymph node sampling and avoidage of tumor spillage (COG) vs. neoadjuvant chemotherapy then nephrectomy (SIOP) Bilateral WT: neoadjuvant chemo in both protocols; nephron-sparing surgery goal Avoid biopsy in unilateral WT (COG) | ||
- Papillary - Trans- location associated - Renal medullary carcinoma - Oncocytic renal cell carcinoma following neuroblastoma | older than 15 years | 2% | hematuria; flank pain | MiT/TFE family translocation RCC (Xp11 TFE3; t[6;11] TFEB) accounts for up to 40–50% of pediatric RCC von Hippel-Lindau Tuberous sclerosis Familial RCC | MiT/TFE tRCC: indolent in children (even with nodal disease), may recur decades later — long-term surveillance required Partial nephrectomy if negative margins achievable 2022 WHO classification separates TFE3-rearranged and TFEB-rearranged RCC as distinct entities | |
11 months (range zero to four years) | 3.7% | fever, hematuria, advanced stage | Brain CT or MRI (concomitant CNS lesion in 10–15%) | Biallelic loss of SMARCB1 (INI1), chromosome 22q11 Germline mutation in ~35%; genetic counseling warranted SMARCA4 (BRG1) alterations in SMARCB1-retained cases | Highly aggressive; no survival without complete resection 10–15% have synchronous CNS rhabdoid tumor EZH2 inhibitor tazemetostat under investigation in INI1-negative tumors | |
Clear cell sarcoma of the kidney | 36 mo (range two months to 14 years) | 3.3% | 2:1 male to female ratio | PET or bone scan, consider brain CT or MRI | BCOR internal tandem duplication (ITD) in ~85–90% YWHAE–NUTM2 fusion in ~5–10% BCOR–CCNB3 fusion (rare) | Brain is frequent site of recurrence COG AREN0321: RT may be omitted for stage I with adequate LN sampling; carboplatin added for stage IV Distinct molecular subtypes; biological significance of variants under investigation |
one to two months (80% present in infancy) | 2.2% | young age 2:1 male to female ratio | t(12;15)(p13;q25), resulting in the ETV6–NTRK3 fusion: ETV6–NTRK3 fusion in cellular subtype (up to 80-90% of cellular CMN) EGFR kinase domain duplication in classical subtype KLHL7–BRAF and other rare fusions described | Excellent prognosis overall; surgery curative in most Upfront nephrectomy preferred (no chemotherapy needed for most) Incomplete resection worsens prognosis ETV6–NTRK3 fusion creates potential for TRK inhibitor therapy (larotrectinib) in recurrent/metastatic cellular CMN | ||
Cystic nephroma | infants/young children or adult females | 2% | multilocular renal cysts | DICER1 mutation (pediatric cases) | Benign; nephrectomy or partial nephrectomy curative | |
Ossifying renal tumor of infancy | less than one year | less than 1% | hematuria is universal | Benign; conservative/nephron-sparing surgery Calcified intraluminal mass in renal pelvis on imaging | ||
* The standard workup includes magnetic resonance imaging (MRI) or computerized tomography (CT) of the abdomen and pelvis with attention to renal vein, inferior vena cava and contralateral kidney; chest CT; complete blood count, serum calcium, platelet count and coagulation profile (to asses for acquired von Willebrand disease) | ||||||
The purpose of the linked sections that follow is to familiarize surgeons with the distinguishing features and management principles associated with renal tumors of childhood, so that optimal surgical and multidisciplinary care can be provided when such patients are encountered.
see also Wilms Tumor, Renal Cell Carcinoma, Rhabdoid Tumor of the Kidney, Clear Cell Sarcoma of the Kidney, Mesoblastic Nephroma, Cystic Nephroma and Nephrectomy for Tumor.
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