Subsegmental renal vein thrombus: Intra-operative diagnosis and management

• Tumour thrombus may be an unexpected intraoperative diagnosis and may require a change to the operative plan – • Robotic resection of tumour thrombus may yield acceptable oncological outcomes • Robotic surgeons must remain aware of the possibility and appearance of tumour thrombus, and be able to adjust accordingly intraoperatively We present a case of a 45mm left renal mass with incidental subsegmental tumour vein thrombus, which was treated with robotic assisted partial nephrectomy and tumour thrombus resection. During tumour resection, a subsegmental vein from the tumour was identified, clipped and ligated, at which time it was noted to contain a tumour thrombus. Resection was extended medially/proximally until all tumour thrombus had been removed. The histopathology showed a chromophobe renal cell carcinoma with clear surgical margins, and she remains tumour free at 18-month surveillance. The presence of tumour thrombus has implications for tumour staging (at least T3a for segmental renal vein) and is typically associated with a worse prognosis. Tumour thrombus should be resected to optimise oncological outcomes, which is typically achieved via radical nephrectomy. Our case demonstrates that when performed by an experienced surgeon, a partial nephrectomy with tumour thrombus dissection may be suitable, and incidental tumour thrombus identified intraoperatively does not necessitate immediate conversion to radical nephrectomy. This case adds to previous evidence demonstrating non-inferior oncological outcomes with partial nephrectomy and tumour thrombus resection, compared to radical nephrectomy. It is important for surgeons to remain vigilant of venous invasion, even in small subsegmental veins, and to intraoperatively adjust margins to ensure all tumour thrombus is resected. With robotic surgery's improved visualisation, we are now able to detect even small subsegmental tumour thrombi and adjust our technique accordingly during the procedure to optimise oncological outcomes, as showcased in this video.