A 72-year-old Japanese man presented with symptoms of chest pain and poor appetite. Contrast-enhanced CT scan showed a solid mass (diameter:80mm) with slight enhancement located in the left inferior posterior mediastinum. The mass surrounded the descending aorta at the T8-T10 level, partly infiltrating the aorta. Primary mediastinal undifferentiated sarcoma was diagnosed by CT-guided percutaneous needle biopsy. No distant metastasis was apparent on whole diffusion MRI. He was scheduled to undergo chemo radiotherapy, but 3weeks after the diagnosis, sudden anuria was observed, and his blood test revealed acute kidney injury and hyperkalemia. Contrast-enhanced CT-scan revealed occlusion of bilateral renal artery at its origin, and hemodialysis was immediately performed. We suspected that occlusion was caused by tumor embolism. The patient received catheter-directed thrombolysis to improve his renal function and to confirm diagnosis. Tumor cells identifiable as primary lesion were pathologically recognized from a part of the embolus collected by the catheter, which proves acute kidney injury secondary to bilateral renal artery tumor thrombosis. After the treatment, the renal dysfunction remarkably improved and he was able to be taken off dialysis.
Intravascular tumor thrombus often occurs in the venous system. However, we present a rare case of undifferentiated sarcoma patient with mediastinal origin that developed acute kidney injury due to bilateral renal artery tumor thrombosis and successfully treated with catheter-directed thrombolysis.