Painless Gross Haematuria with a 3 cm Enhancing Renal Mass in a Solitary Functioning Kidney
A 62-year-old man with type 2 diabetes (HbA1c 7.8%), hypertension, and a body mass index of 34 presents with two episodes of painless gross haematuria. CT with contrast shows a 3.2 cm exophytic, enhancing, partly necrotic mass in the interpolar region of the right kidney. The left kidney is atrophic (7.5 cm) with a split function of 12% on renography; serum creatinine is 168 micromol/L, eGFR 38 mL/min/1.73 m2. There is no venous thrombus, no lymphadenopathy, and no distant metastasis. He has had one previous episode of angina and an ejection fraction of 45%.
1. How would you stage and risk-stratify this lesion, and what does the solitary functioning kidney add to your operative planning?
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Staging: Contrast-enhanced CT of chest, abdomen and pelvis is the staging standard; this shows a cT1b (3.2 cm) N0 M0 renal mass. A 3.2 cm lesion is T1b (T1a is <=4 cm only when confined; the 4 cm boundary separates T1a from T1b), so I would describe it as cT1bN0M0. Biopsy is not mandatory before surgery in a fit patient with a solid enhancing mass, but it becomes attractive here because of competing priorities (surgical vs ablative vs observation) and the need to know histology before committing a solitary kidney to resection.
Risk stratification: The dominant issue is not oncological but functional. The contralateral kidney contributes only 12% of total function and is atrophic, so this is functionally a solitary kidney with a baseline eGFR of 38. Every nephron removed is unrecoverable, and the patient is at high risk of perioperative acute kidney injury and of progressing to dialysis.
Planning implications:
- Nephron-sparing surgery is mandatory, not optional; radical nephrectomy would render him dialysis-dependent.
- Preoperative planning must include tumour complexity scoring (RENAL or PADUA), assessment of the tumour-to-collecting-system distance, and a decision on clamping strategy (selective arterial clamping, off-clamp, or early unclamping) to limit warm ischaemia.
- Baseline CKD (eGFR 38) plus diabetes means a multidisciplinary discussion with nephrology, careful volume and drug management (avoid nephrotoxins, hold metformin, avoid NSAIDs), and consent that covers the possibility of temporary or permanent renal replacement therapy.
- Cardiac risk (previous angina, EF 45%) requires anaesthetic optimisation before an operation that may involve significant blood loss and fluid shifts.
2. The tumour abuts the renal sinus and is technically difficult. Compare partial nephrectomy, thermal ablation and active surveillance in this specific patient, and justify your recommendation.
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Partial nephrectomy gives the best long-term oncological control for a T1b mass and preserves renal function, but in a solitary kidney with a sinus-adjacent tumour it carries the highest risk of urine leak, bleeding, positive margins and conversion to radical nephrectomy. It is still the reference standard for a fit 62-year-old with a 3.2 cm mass, provided the surgeon can achieve negative margins while preserving enough parenchyma.
Thermal ablation (radiofrequency or cryoablation) is attractive in a solitary kidney because it preserves more parenchyma and has a lower major-complication rate. Its weaknesses are the lack of a specimen for histology, a higher rate of local recurrence (particularly for tumours >3 cm and central tumours, where heat-sink effects and proximity to the collecting system reduce efficacy), and the need for rigorous imaging follow-up. For a 3.2 cm central tumour in a solitary kidney it is a reasonable option only if surgery is contraindicated or the patient declines it, and it should be preceded by biopsy.
Active surveillance is defensible for small renal masses in frail patients, but a 3.2 cm mass with necrosis in a 62-year-old with a good performance status has meaningful metastatic potential, and deferring treatment in a functionally solitary kidney risks losing the window in which nephron-sparing surgery is feasible.
Recommendation: Offer partial nephrectomy as first-line in a high-volume centre, with a clear preoperative plan for hilar dissection, cold or selective clamping, and intraoperative decision-making about margins. If the tumour proves unresectable without sacrificing the kidney, convert to ablation or, as a last resort, radical nephrectomy with planned dialysis and transplant assessment. Shared decision-making should include the possibility of a two-stage approach (biopsy then ablation) if the patient prioritises renal preservation.