Wilms Tumor
In a pediatric patient presenting with an abdominal mass and severe hypertension (BP 150/90 mmHg), the most likely diagnosis is Wilms tumor (nephroblastoma).
Clinical Reasoning
Why Wilms Tumor is the Most Likely Diagnosis
Wilms tumor is the most common renal malignancy in children, accounting for approximately 90% of all childhood renal malignancies and 5-7% of all pediatric cancers, with peak incidence around age 3-3.5 years 1, 2.
The classic presentation of Wilms tumor is an abdominal mass (often discovered incidentally by parents during bathing or dressing), which is the most common presenting feature in the majority of cases 1, 3.
Hypertension occurs in approximately 25% of Wilms tumor patients due to renin secretion by the tumor or compression of renal vasculature, making the combination of abdominal mass + hypertension highly suggestive of this diagnosis 1.
Why Not Neuroblastoma
Neuroblastoma typically presents with elevated urinary catecholamines (VMA, HVA) and catecholamine-related symptoms such as flushing, sweating, and diarrhea, which are not mentioned in this case 4.
Neuroblastoma more commonly involves bone or bone marrow metastases at presentation, whereas Wilms tumor typically metastasizes to lungs 4.
While neuroblastoma can cause hypertension, it is less commonly associated with a palpable renal mass as the primary presenting feature compared to Wilms tumor 4.
Why Not Liver Tumor
Hepatoblastoma (the most common primary liver malignancy in children) presents with elevated alpha-fetoprotein (AFP) levels and a hepatic mass on imaging, not a renal mass 4.
The location of the mass (abdominal, likely renal given the hypertension) points away from a primary hepatic tumor 4.
Immediate Diagnostic Workup
First-Line Imaging
Abdominal ultrasound is the optimal initial screening tool because it is widely available, lacks ionizing radiation, can be performed without sedation, and has high sensitivity for detecting renal masses 4.
Doppler ultrasound should evaluate the inferior vena cava for tumor thrombus extension, which occurs in a subset of Wilms tumor cases 4.
Assess the contralateral kidney during initial ultrasound to evaluate for bilateral disease, which occurs in approximately 5-10% of cases 4.
Additional Imaging Considerations
CT or MRI of the abdomen is typically performed after ultrasound confirmation to better define tumor extent, vascular involvement, and lymph node status 4.
MRI is preferred when evaluating bilateral tumors, detecting nephrogenic rests, or planning potential nephron-sparing surgery 4.
Chest imaging (CT chest) is essential to evaluate for pulmonary metastases, the most common site of distant spread 4.
Laboratory Evaluation
Complete blood count, renal function tests, and urinalysis should be obtained as baseline studies 4.
Urinary catecholamines (VMA, HVA) should be measured to help differentiate from neuroblastoma if the diagnosis remains uncertain 4.
Critical Management Principles
Surgical Approach
The North American Children's Oncology Group (COG) recommends upfront nephrectomy for unilateral tumors without pre-operative biopsy, as biopsy risks tumor spillage and upstaging, which would necessitate more intensive chemotherapy and radiation 4.
Nephron-sparing surgery should be considered for bilateral or syndromic Wilms tumor when technically feasible, given the increased risk of recurrence in the remaining kidney tissue 4.
Genetic Testing Indications
Universal genetic testing and counseling is recommended for all children with bilateral Wilms tumors, including methylation and copy-number analysis of chromosome 11p15.5, sequencing of WT1, and testing for common predisposition genes 4.
Patients with genetic predisposition syndromes (WT1, Beckwith-Wiedemann, DICER1) require renal ultrasound surveillance every 3 months until age 7-8 years 4.
Common Pitfalls to Avoid
Do not delay imaging in a child with an abdominal mass and hypertension—this combination warrants urgent evaluation for Wilms tumor 1.
Do not perform pre-operative biopsy of a suspected unilateral Wilms tumor, as this risks tumor spillage and upstaging 4.
Do not miss bilateral disease—always carefully evaluate the contralateral kidney on initial imaging, as bilateral involvement significantly alters management 4.
Do not overlook genetic predisposition syndromes—certain features (bilateral disease, very young age, associated anomalies) should prompt genetic evaluation 4.
Prognosis
Modern multimodal treatment has achieved overall survival rates of approximately 90% for Wilms tumor, representing one of the major success stories in pediatric oncology 5.
Prognosis remains worse (approximately 75% survival) for patients with anaplastic histology, bilateral disease, or recurrent disease 5.