Mixed epithelial and stromal tumor of the kidney--a case report

A 45-year-old woman had gross hematuria without flank pain for two weeks. She visited our hospital and a renal echo showed a heterogenous mass on the left kidney. Abdominal computed tomography showed a multicystic tumor, about 7 cm, on the left renal pelvis and the proximal ureter. The tumor was enhanced after contrast injection. Ureteroscopy showed an intraluminal polypoid tumor. Cystic renal cell carcinoma or urothelial carcinoma was suspected preoperatively. We performed a hand-assisted laparoscopic nephroureterectomy, and the post-operative course was uneventful. The pathology report demonstrated that the tumor was composed of an admixture of stroma and flattened to cuboidal urothelium. The tumor stromal cells expressed both estrogen and progesterone receptors, and no malignant cells were found. There has been no recurrence or deterioration of the patient's renal function since surgery. We suggest keeping in mind the diagnosis of mixed epithelial and stromal tumor of the kidney when encountering perimenopausal women with renal cystic tumors.