Renal cell carcinoma (RCC) is the most common solid lesion of the kidney and accounts for around 90% of all kidney tumors. RCC is known to produce high levels of angiogenic growth factors like vascular endothelial growth factor (VEGF) due to abnormality of von Hippel-Lindau gene (VHL) giving the tumor a vascular appearance. Renal arteriovenous malformation (AVM) is a rare and acquired aberrant vascular communication. It can present in RCC as masquerading the lesion by forming AVM within the lesion or can present as an associated finding along with RCC or rarely even present as a metastatic lesion.

53-year male patient presented with left flank pain for 6 months. He got evaluated contrast CT of abdomen which showed exophytic upper pole heterogeneously enhancing mass of 3.5x3.4x3.3 cm with multiple tortuous collaterals. Left renal artery and veins were dilated with 1cm and 2.7cm respectively. Whole body FDG-PET/CT showed metabolically active left renal mass with multiple bilateral pleural and parenchymal based soft tissue nodules of largest 1cm with enlarged paratracheal nodes of 14mm suggestive of metastasis. On clinical examination, he had left grade 3 varicocele. We reviewed all the imaging in our hospital and he was diagnosed with metastatic renal mass with renal AVM of 5 x4 cm.

He underwent preoperative angiography with renal artery embolisation followed by left laparoscopic cytoreductive nepherectomy on the same day. Angiography showed early enhacement of dilated renal vein with renal AVM. Embolisation coil was placed in the main renal artery just distal to branching of the superior renal artery for space of intraop ligation of vessels. Intraoperatively, there were multiple dilated collaterals along the perinephric space with dilated renal vein.

RCC with renal AVM is a rare association.