On intravenous urography (IVU), the 'rim sign' (shell of opacified parenchyma around a lucent central area) in the kidney is seen in which condition?

• A Hydronephrosis — severely dilated renal pelvis compressing functional parenchyma ✓
• B Transitional cell carcinoma of the renal pelvis
• C Renal artery stenosis with reduced GFR
• D Xanthogranulomatous pyelonephritis

Explanation

The rim sign on IVU refers to a thin crescent of opacified compressed renal parenchyma surrounding a markedly dilated collecting system or a renal mass. In the context of hydronephrosis, it indicates severely reduced but preserved renal function with very thin remaining cortex. The sign also applies to renal cyst or tumour compressing remaining parenchyma. TCC causes a filling defect in the collecting system. Renal artery stenosis causes a small kidney with prolonged nephrogram. XGP shows a non-functioning kidney with calculi.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.