Renal Oncocytoma Presenting as a Huge Hypervascular Mass on Ultrasound

Abstract

With the increasing use of ultrasonography, renal incidentaloma cases have also been rising. A solid renal mass observed incidentally will either be malignant or benign. Of malignant renal tumors, renal cell carcinoma (RCC) is the most common. The two most common benign tumors that need to be differentiated from RCC are oncocytoma and angiomyolipoma. It is difficult to differentiate benign from malignant tumors on ultrasonography. Furthermore, there are also difficulties distinguishing oncocytoma from RCC due to the nonspecific clinical presentation and overlapping imaging findings. Thus, renal oncocytomas are often removed by nephrectomy despite their benign nature. We report the case of a tumor that was suspected to be RCC preoperatively on ultrasonography and computed tomography but was diagnosed as oncocytoma postoperatively.