What is the most likely diagnosis for a pediatric patient with an abdominal mass and hypertension?

Most Likely Diagnosis: Wilms Tumor

In a pediatric patient presenting with an abdominal mass and hypertension (BP 150/100), Wilms tumor is the most likely diagnosis, as it is the most common cause of severe hypertension among pediatric abdominal malignancies, affecting approximately 20% of Wilms tumor cases. 1

Diagnostic Reasoning

Hypertension as a Key Discriminator

• Wilms tumor causes severe hypertension in 20% of cases, making it the most frequent abdominal malignancy associated with this finding in young children 1
• Neuroblastoma causes hypertension in only 10% of cases, making it less likely when hypertension is the prominent feature 1
• The hypertension in Wilms tumor is typically asymptomatic but severe (often >99th percentile + 30 mmHg), which matches this clinical presentation 1
• The mechanism involves renal parenchymal disease and renin-mediated hypertension from the tumor's renal origin 2

Age and Presentation Patterns

• Hypertension with abdominal tumors most commonly affects children under 2.5 years of age, with Wilms tumor being the predominant diagnosis 1
• Wilms tumor characteristically presents as a renal mass detected on ultrasound, which is the recommended initial screening tool 3

Distinguishing Features from Other Diagnoses

Neuroblastoma would be less likely because:

• It causes hypertension less frequently (10% vs 20%) 1
• When neuroblastoma causes hypertension, it typically presents with elevated urinary catecholamines (vanillylmandelic acid, homovanillic acid) and catecholamine-related symptoms like flushing and sweating 3, 4
• Neuroblastoma more commonly shows bone/bone marrow metastases rather than isolated abdominal mass 3

Hepatoblastoma would be unlikely because:

• It presents with elevated AFP levels and hepatic (not renal) mass on ultrasound 3
• Hypertension is not a characteristic feature of hepatoblastoma

Recommended Diagnostic Workup

• Abdominal ultrasound with Doppler to confirm renal origin of the mass and evaluate for inferior vena cava tumor extension 3, 2
• Urinalysis, serum creatinine, and electrolytes to assess renal function 2
• Ambulatory blood pressure monitoring (ABPM) to confirm true hypertension if time permits, though the severity here (150/100) likely warrants immediate action 5, 2

Management Priorities

• Initiate antihypertensive therapy immediately given the severe elevation (BP 150/100) - calcium channel blockers (nicardipine) or ACE inhibitors are first-line agents 2, 1
• The hypertension typically resolves after tumor treatment (median duration of antihypertensive therapy is 40 days) 1
• Primary chemotherapy and/or surgical resection of the tumor is the definitive etiologic treatment 1

Common Pitfall to Avoid

Do not delay imaging and oncologic referral while pursuing extensive hypertension workup - the abdominal mass itself is the critical finding that requires urgent evaluation, and the hypertension will resolve with tumor treatment 1