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Unusual case of multilocular cystic renal cell carcinoma treated with nephron-sparing technique.

INTRODUCTION
The spectrum of cystic renal neoplasms includes both benign and malignant tumors and the order is as follows: benign multilocular cyst, multilocular cystic renal cell cancer and cystic renal cell cancer. Gross similarities among multicystic tumors of the kidney may cause conflict in the diagnosis and treatment of these lesions.


CASE REPORT
We report a 37-year-old male who presented with a mild persistent left flank pain and a painful left renal mass. After a series of examinations including abdominal ultrasound, intravenous pyelography and computed tomography, he underwent surgical exploration despite the benign appearance on radiological evaluation. A partial nephrectomy has been finally performed. The pathologic examination showed multilocular cysts lined by flattened to cuboidal epithelium, separated by cellular spindle cell stroma. Few scattered foci of lining cells showing the typical features of clear cell carcinoma of the kidney have been revealed also.


CONCLUSION
According to the current literature, prognosis of multilocular renal clear cell carcinoma is excellent in most of the cases. Indeed, metastases development is rare while local recurrence is related to inadequate local excision. Despite the relatively benign nature, urologist should be always aware of such complex renal masses since both the non specific clinical findings and poor contribution of imaging examinations make the preoperative distinction of benign from malignant cystic renal neoplasias difficult.