A Rare Case of Bilateral Multilocular Renal Cysts

Abstract

Several names have been used to describe a rare multiloculated cystic lesion in the kidney, including benign multilocular cyst, multilocular cystic nephroma, cystic nephroma and others. The abundance of names is partially attributable to an incomplete understanding of the etiology and natural history of this condition. Most authorities believe that this lesion is part of a spectrum of renal cystic disorders with multilocular cyst and cystic Wilms tumor representing the 2 extremes. Whatever the etiology, multilocular cysts have a typical radiographic appearance, are almost uniformly unilateral and are treated with curative nephrectomy. We report a unique case of bilateral multilocular renal cysts treated with bilateral partial nephrectomy. CASE REPORT A 15-month-old Hispanic boy presented with a 3-month history of progressively enlarging bilateral flank masses, and nausea, vomiting and anorexia 1 week in duration. There was no other significant medical history. Physical examination revealed blood pressure of 100/60 mm. Hg and abdominal examination demonstrated bilateral 12 to 14 cm., nontender, nonfixed, firm flank masses. Serum electrolytes, urea nitrogen, creatinine, hemoglobin and urinalysis were normal. Abdominal ultrasound and computerized tomography showed 10 X 12 cm. cystic renal masses with multiple septa (fig. 1). A rim of normal appearing renal parenchyma (right side greater than left side) was displaced inferiorly and medially. 3-Mercaptoacetyltriglycine nuclear renal scan revealed that 80% of renal function was by the right kidney. Abdominal exploration was planned but moderate hypertension developed, which was controlled with oral calcium channel blockers. Subsequently exploration was performed through a transperitoneal midline incision. The left renal mass was approached first, revealing a firm mobile cystic renal mass contiguous with the inferior pole of normal appearing renal tissue. Because of the benign appearance of this mass and bilateral involvement, a nephron sparing procedure was performed involving partial nephrectomy with renal reconstruction. The mass was completely excised en bloc (fig. 2). However, the dilated renal pelvis was opened to extrude the inferior aspect of the mass, which had herniated into the collecting system. Frozen section was consistent with a multilocular renal cyst without evidence of malignancy. Exploration of the right side revealed similar fmdings and an identical procedure was performed. Postoperatively the patient recovered well. He is currently asymptomatic and thriving, and hypertension has completely resolved. Followup renal scan and ultrasound 6 months postoperatively demonstrated excellent function of both remaining renal units with no evidence of any recurrent cystic lesions. The final pathological diagnosis was consistent with bilateral benign multilocular renal cysts.