Is it possible to diagnose mixed epithelial and stromal tumor of kidney prior to surgery? A case report

We present a case in which renal mixed epithelial and stromal tumor (MEST) was considered in the differential diagnosis based on preoperative imaging findings. A 38-year-old woman was found to have a right renal tumor during an abdominal ultrasound examination conducted as part of a health checkup. Contrast-enhanced computed tomography revealed a 50 × 40-mm mass in the middle of the right kidney. The possibility of papillary renal cell carcinoma was considered. However, given the patient's age, sex, and characteristics of the mass, MEST was also considered a differential diagnosis. The patient underwent laparoscopic radical right nephrectomy. The tumor was diagnosed as MEST.