Description

A 43-year-old woman presented with a 2-year history of an intermittent focal protruding abdominal mass. She could palpate the mass around the epigastrium when she lies down supine but not in an erect position, and it would disappear when she pushed it. She did not report abdominal pain, flank pain or haematuria. No abdominal mass was palpable during physical examination either in the supine or erect position. A standing abdominal radiograph showed a small and round-shaped right kidney descent (>5 cm) near the pelvis known as the ‘tennis ball kidney’ (figure 1A, arrow). Nephroptosis was confirmed after a supine radiograph showed that the right kidney moved back into a normal anatomical site (figure 1B) and excluded an ectopic kidney. Her renal function was normal and urinalysis was unremarkable. A renal ultrasonography showed no hydronephrosis. Because she was relatively asymptomatic, only observation with follow-up was recommended.

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Figure 1

A standing abdominal x-ray (A) showing a significant downward displacement (>5 cm) of the kidney (arrow). The supine abdominal x-ray (B) showing right kidney in the normal position.