Abdominal Masses
PEDIATRICS
An abdominal mass in children most commonly arises from the urinary tract or adrenals and should therefore be worked up by a urologist until imaging studies prove otherwise. A hydronephrotic kidney secondary to ureteropelvic junction (UPJ) obstruction is the most common cause of a unilateral abdominal mass in childhood, followed by a multicystic kidney. Neuroblastomas or Wilms’ tumor are the most common cause of a solid abdominal mass in children.
▪ Differential Diagnosis of Abdominal Mass in Children | |||||||||||||
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Imaging Techniques
Ultrasound should be the first imaging study performed. It will provide differentiation of solid from fluid- or blood-filled masses in most cases and give localization to a specific area of the abdomen.
Computed tomography (CT) will give more accurate anatomic localization of solid masses and help further differentiate equivocal masses as solid versus cystic.
Intravenous (IV) urography is often unsatisfactory during the first weeks of life because of the poor concentrating ability of the neonatal kidney. However, it provides valuable anatomic and functional detail for diagnosis of retroperitoneal masses.
The addition of a Lasix washout test can help identify partial obstruction.
MAG3 (mertiatide) renal scan with Lasix is an alternative first choice for the clearly cystic mass. It will give information on renal function and identify partial UPJ obstruction.
Voiding cystourethrography should be performed on all hydronephrotic masses to differentiate obstruction from reflux.
Anterograde pyelography via a percutaneous nephrostomy is often helpful to determine the level of obstruction while providing urinary drainage and information on the potential for functional recovery of the kidney.
Cystoscopy with retrograde pyelography will provide information on the status of the lower ureter and bladder when needed.
ADULTS
Renal masses are increasingly being discovered incidentally during abdominal CT scans or ultrasound performed for unrelated reasons. These masses will require further workup for definitive diagnosis and treatment if indicated. The classic triad of flank mass, flank pain, and hematuria that heralds a renal cell carcinoma occurs in only 10% of patients.
▪ Differential Diagnosis of a Flank Mass in Adults |
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