A 3 cm renal mass in a solitary kidney with CKD
A 74-year-old man has a 3.1 cm incidentally detected mass in the posterior upper pole of his left kidney. He underwent right radical nephrectomy 15 years ago for a pT1b clear cell carcinoma and has had no recurrence. Comorbidities are type 2 diabetes (HbA1c 8.2%), hypertension and stable angina; he walks with a stick after a hip replacement. Blood pressure 152/88 mmHg, BMI 31. Creatinine 210 µmol/L, eGFR 34 mL/min/1.73 m²; haemoglobin 108 g/L; no proteinuria. CT shows an exophytic, largely posterior, solid 3.1 cm mass with a RENAL nephrometry score of 6, no renal vein involvement, no lymphadenopathy and no metastases on staging CT. The contralateral renal fossa is empty. He is keen to avoid dialysis and asks whether 'they can just burn it'. The anaesthetist grades him ASA III and estimates a moderate perioperative risk.
1. What are the realistic options, and what would you recommend? Give your reasoning.
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The tumour is cT1a (3.1 cm), exophytic and posterior, which is favourable for both nephron-sparing surgery and ablation; the patient has a solitary kidney and significant chronic kidney disease (eGFR 34), so preserving renal function is the dominant consideration alongside oncological control.
The options are partial nephrectomy, thermal ablation (radiofrequency, microwave or cryoablation) and active surveillance. Radical nephrectomy is not appropriate: it would render him anephric and commit him to dialysis.
Partial nephrectomy gives the best oncological control for cT1a, with local recurrence rates of a few percent, but requires clamping and resection of parenchyma. In a solitary kidney, warm ischaemia should be limited, ideally off-clamp or with selective clamping and under 20–25 minutes. His cardiac disease and diabetes increase perioperative risk but do not make surgery unreasonable at a moderate estimated risk. Ablation is a valid alternative for a posterior exophytic cT1a of this size: it is less invasive and better preserves function, but local recurrence is higher and repeat treatment or later surgery may be needed. Active surveillance is reasonable only if his life expectancy or fitness makes intervention unattractive; he is symptomatic of neither and is motivated to avoid dialysis.
My recommendation: discuss in a multidisciplinary meeting, offer partial nephrectomy as first choice if technically feasible with limited ischaemia, and offer ablation as an equivalent option given comorbidity, with shared decision-making. Renal mass biopsy is sensible if ablation or surveillance is chosen, to confirm histology.
2. If he chooses partial nephrectomy, what specific measures reduce the risk of dialysis?
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The aim is to remove the tumour with a clear margin while preserving as much functioning parenchyma as possible, because residual nephron mass, not just ischaemia time, determines postoperative function.
Preoperatively, optimise blood pressure and diabetes control, stop nephrotoxic drugs, avoid dehydration, and involve nephrology in planning. Intraoperatively, use an open or robotic approach with intraoperative ultrasound to define the tumour; perform enucleation or a minimal-margin resection; use off-clamp excision or selective arterial clamping where the anatomy allows; if global clamping is needed, keep warm ischaemia under 20–25 minutes, and use cold ischaemia for complex repair. Avoid hypotension and excessive fluid shifts, and maintain perfusion pressure. Reconstruct the collecting system carefully and achieve haemostasis without compromising remaining vessels; use haemostatic agents judiciously. Postoperatively, avoid NSAIDs and contrast where possible, monitor creatinine and urine output, and manage fluid balance closely.
If the tumour proves centrally located or adherence to hilar vessels makes a safe partial nephrectomy impossible, the MDT should reconsider ablation rather than defaulting to radical nephrectomy. Preoperative counselling should include the possibility of temporary or permanent renal replacement therapy and the need for nephrology follow-up.
3. What is the role of renal mass biopsy here, and how would you follow him up after treatment?
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Biopsy is most useful when it will change management. If he chooses ablation, percutaneous core biopsy before treatment confirms malignancy and subtype and provides a baseline for later surveillance, since ablation destroys the specimen; small biopsies can underestimate grade, so a negative biopsy does not fully exclude carcinoma. If he chooses partial nephrectomy, biopsy is not mandatory because the specimen gives the diagnosis. If active surveillance is being considered, biopsy and grading help define the risk of progression. In a solitary kidney, histology also informs the intensity of follow-up.
After partial nephrectomy or ablation, follow-up should include history, examination and renal function at each visit, with cross-sectional imaging of the treated kidney and chest imaging according to recurrence risk. Typically, imaging is performed at 3–6 months to establish a baseline, then annually for at least five years. After ablation, earlier and more frequent imaging is used because local recurrence is more common and can be salvaged. Residual or recurrent enhancement should prompt repeat ablation or surgery.
He also needs active management of CKD: blood pressure control, glycaemic control, avoidance of nephrotoxins and discussion with nephrology about progression. The risk of contralateral metachronous tumour is not relevant here, but solitary kidney function remains the main long-term threat.