A 38-year-old woman presents with painless haematuria. CT urography shows a 3 cm filling defect in the left renal pelvis on the excretory phase. The filling defect is irregular, non-calcified, and does not shift with position change. Overlying parenchyma is normal. What is the most likely diagnosis?
- A Urothelial (transitional cell) carcinoma of the renal pelvis ✓
- B Renal calculus causing obstruction
- C Renal cell carcinoma invading the collecting system
- D Sloughed renal papilla
Explanation
Urothelial carcinoma (transitional cell carcinoma) of the upper urinary tract characteristically presents as a non-mobile, irregular filling defect within the collecting system on CT urography excretory phase. Key distinguishing features from calculi: calculi are hyperdense on non-contrast CT and may demonstrate acoustic shadowing; sloughed papillae have a characteristic triangular shape or the 'ring sign' of contrast around the papilla. Renal cell carcinoma arises from the parenchyma and may invade the collecting system, but the described case shows a normal overlying cortex. The non-positional nature excludes a mobile calculus or blood clot.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.