A child presents with a painless, palpable abdominal mass that does not cross the midline. Which diagnosis is most likely?

• A. Neuroblastoma
• B. Renal Cell Carcinoma
• C. Hepatoblastoma
• D. Wilms Tumor

Answer: (D)

The key idea here is that in children a painless abdominal mass that stays on one side and does not cross the midline strongly suggests a renal origin. Wilms tumor, a nephroblastoma, fits this pattern. It usually presents in young kids as a large, smooth, unilateral renal mass that is painless and does not cross the midline. Imaging typically shows a mass arising from the kidney itself, and the condition can be associated with hypertension from renin production. This combination—painless abdominal fullness, a unilateral renal-origin mass, and lack of midline crossing—makes Wilms tumor the most likely diagnosis.

Neuroblastoma often sits near the adrenal gland and tends to cross the midline and encase vessels, sometimes with systemic symptoms. Hepatoblastoma would arise in the liver, presenting as a liver-origin mass rather than a renal one. Renal cell carcinoma is much less common in children and would have a different clinical pattern.