Multilocular cysts of kidney. A study of 29 patients and review of literature.

Multilocular renal cyst is a distinct renal tumor whose gross external appearance and absence of normal renal tissue within the septa of loculi distinguish it clearly from other renal cystic lesions. Interlocular septa may contain either (1) fibrous tissue alone or (2) embryonic tissue separating adjacent loculi. Of 29 patients with multilocular renal cysts, 24 underwent a renal-sparing procedure, and only 5 had radical nephrectomy. None of the histologic specimens showed evidence of immature renal tissue or neoplasia. Patients were followed from three months to eight years (mean, 39 months), and no evidence of local recurrence or metastatic disease was found. Because it is difficult to distinguish multilocular renal cyst from cystic Wilms tumor and multicystic clear cell carcinoma on the basis of imaging studies alone, surgical intervention is the only effective method to differentiate multilocular renal cyst from a malignant lesion of the kidney.