A -year-old boy is brought to the pediatrician's office by his father, who noticed a firm, painless swelling on the right side of the child's abdomen while dressing him. The child has been eating well, is as active as usual, and has had no fever, vomiting, or bone pain. Vital signs are within normal limits for age, except for a blood pressure of mmHg (which is th percentile for his age). On physical examination, a smooth, firm, non-tender mass is palpated in the right upper and lower quadrants; it does not cross the midline. The remainder of the examination is unremarkable. Urinalysis reveals - red blood cells per high-power field. Which of the following is the most appropriate next step in the evaluation of this patient?
- AComputed tomography of the abdomen with contrast
- BMeasurement of urinary homovanillic acid and vanillylmandelic acid
- Abdominal ultrasonographyAnswer
- DPercutaneous core needle biopsy of the mass
- EObservation and repeat physical examination in 4 weeks
Answer
Abdominal ultrasonography
The correct answer is abdominal ultrasonography. This patient's presentation of a unilateral, painless, firm abdominal mass that does not cross the midline, accompanied by hypertension and microscopic hematuria, is highly suspicious for a Wilms tumor (nephroblastoma). The most appropriate initial step in the evaluation of a pediatric abdominal mass is an ultrasound. It is a rapid, non-invasive imaging modality that avoids ionizing radiation. Ultrasonography can confirm the presence of a mass, differentiate between cystic (e.g., hydronephrosis) and solid structures, and identify the organ of origin (e.g., intrinsic renal mass versus an extrinsic mass like neuroblastoma), which effectively guides the next steps in management and staging.
Step-by-Step Solution
Key Concept
Wilms tumor presentation and initial diagnostic workup
Estimated Time:1m 0s