A 56-year-old patient was referred to our department due to an incidental finding of a renal mass of 5 cm maximum diameter, left mesorenal on ultrasound during the study of a renoureteral crisis on the same side. The patient's only history was hyperuricaemia, and he did not report any episodes of haematuria. At the centre where the diagnosis was made, an extension study was performed with chest X-ray, haemogram, biochemistry and abdomino-pelvic computerised tomography, which revealed a tumour thrombus extending through the renal vein to the retrohepatic vena cava. In this case, the referring centre decided to place a filter in the inferior vena cava to prevent progression and embolisation of the thrombus. The patient was subsequently referred to our centre to assess surgical treatment, as the sending centre did not have a cardiac surgery service.
To complete the study, we performed magnetic resonance urography (Uro-MRI) and angiographic study by computerised tomography (angio-CT) with cavography to assess as accurately as possible the extent of the thrombus and possible tumour vascular infiltration. Both scans report the retrohepatic extension of the thrombus, the apparent absence of vascular infiltration and adenopathy, as well as the presence of a metallic filter immediately above the thrombus, responsible for the artefaction of the images.

With the diagnosis of stage T3bN0M0 renal neoformation with level II tumour thrombus, it was decided to intervene, together with the cardiac surgery department of our centre, performing sternotomy and left subcostal laparotomy and, after freeing the splenic angle of the colon by opening the retroperitoneum at the level of the mesentery, left radical nephrectomy with the nephrectomy specimen remaining anchored by the thrombosed renal vein. Subsequently, and under extracorporeal circulation with deep hypothermia and cerebral retroperfusion, the filter is removed by closing it and traction under fluoroscopic control from its insertion point at jugular level, with control by right auriculotomy of the possible dissemination to the lung of small thrombi during the removal manoeuvre, followed by resection of the renal vein and its ostium due to suspicion of infiltration of the same and thrombectomy by traction to subsequently repair the defect with a Goretex® patch, the patient requiring anticoagulation with dicoumarinic drugs for 3 months until endothelisation of the synthetic graft.

The pathological anatomy reveals the existence of renal adenocarcinoma, Furhman grade III, which infiltrates the renal capsule without going beyond it, as well as the renal vein, without infiltrating the vena cava (pT3bNoMo) with thrombus of exclusively tumour origin.
The patient continued to undergo check-ups in our consultations until, at the 12-month follow-up CT scan, a lytic lesion was found in the posterior lamina of the L2 vertebra. After an extension study with scintigraphy and total-body CT confirmed that it was a single lesion, he was referred to the neurosurgery department, where he underwent surgery and resection of the lesion was carried out. Currently, 20 months after the nephrectomy, the patient is undergoing check-ups by our service and the medical oncology service, and is asymptomatic and with no signs of recurrence.