Multilocular renal cysts with renal cell carcinoma: report of four cases.

According to Bosniak's classification, renal cysts with moderate calcification, irregular margins, and thickened enhanced septa should raise a suspicion of malignancy. Diagnosis of multilocular renal cysts depends on their histological features. Since 1951, it has generally been considered that a multilocular renal cyst can change from a benign lesion to one which may be combined with malignant change. According to a report from Japan, multilocular renal cysts with renal cell carcinoma are uncommon, and the reported incidence was about 9%. A radical nephrectomy was performed for malignant change. Herein, we present 4 cases of multilocular cyst (Bosniak's class IV) with renal cell carcinoma and review the related literature for their pathogenesis and management.