RADICAL CYSTECTOMY IN PRESENCE OF

FUSED “CAKE” KIDNEY

WILLIAM VAUGHN, M.D. DAVID HICKEY, F.R.C.S.I. WILLIAM HUGHES MILAM, M.D. MARK SOLOWAY, M.D.

From the Department of Urology, University of Tennessee Center for the Health Sciences, Memphis and Baptist Memorial Hospitals in Memphis, Tennessee, and Tupelo, Mississippi

ABSTRACT-Radical cystectomy is the optimal treatment for patients with invasive bladder can- cer. The presence of a fused pelvic kidney is an uncommon congenital abnormality and when found in a patient with bladder cancer may alter the operative procedure. Herein we report on a patient presenting with invasive bladder cancer and a pelvic “cake” kidney.

Invasive bladder cancer accounts for 3 per cent of cancer deaths,’ with radical cystectomy as the standard local therapy in the United States. This case report describes how a radical cystec- tomy was performed in the presence of a pelvic “cake” kidney.

Case Report

A sixty-year-old white man presented in July, 1985, after one episode of painless hematuria. Urologic evaluation included an excretory uro- gram (IVP), cystoscopy with biopsies, and CT scan (Figs. 1 and 2). These studies revealed a fused pelvic kidney, an obstructed left ureter, and a sessile bladder tumor located at the left ureteral orifice. A biopsy specimen revealed a grade III, Stage B transitional cell carcinoma. Arteriography showed two arteries supplying the right portion of the fused kidney, one origi- nating from the common iliac and the other from the internal iliac. The left moiety was sup- plied by two arteries arising from the common iliac artery (Fig. 3). A workup for metastatic disease was negative.

The peritoneal cavity was explored. There was no evidence of intraperitoneal metastases.

The pelvic kidney was fixed to the sacrum and made the left pelvic lymph node dissection dif- ficult. By retracting the fused kidney superiorly, the bladder and prostate were removed in standard fashion without difficulty.

An ileal conduit was selected for urinary diversion. Both ureters were short, less than 5 cm. The left ureter could not be brought retro- peritoneally. A 30-cm segment of ileum was

FIGURE 1. CT scan shows dilated left ureter with thickening of bladder base on left side; tumor does not extend beyond bladder wall.

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FIGURE 2. CT scan of pelvis shows fused pelvic kidney; right renal pelvis is evident.

FICURE~. (A) Selective angiogram of left iliac artery shows two renal arteries arising from left common iliac artery. (B) Right iliac artery angio- gram depicts two right renal arteries; superior artery originates from distal common iliac ar- tery and inferior from internal iliac artery.

Comment

The term fused pelvic kidney, cake kidney, or lump kidney is defined by Glenn2 as an anom- aly in which “the entire renal substance is fused into one mass, lying in the pelvis, and giving rise to two separate ureters which enter the bladder in normal relationship.” It is a rare anomaly. Shiller and WiswelP reporting on a case in 1957 noted only 9 previously reported cases. In 2,153 autopsies in children, Ruben- stein, Meyer, and Bernstein4 found 180 in- stances of urinary tract anomalies, none of which represented a complete pelvic fusion of the kidneys.

Fusion occurs when each metanephric mass is still in the pelvis early in its ascent. An abnor- mally placed umbilical artery may force the two metanephric masses into opposition, lead- ing to fusion5 Following fusion, ascent to the

isolated. The proximal end of the conduit was brought through the sigmoid mesentery, and the left ureteral-ileal anastomosis was performed over a stent. The right ureter was similarily anastomosed (Fig. 4). The stoma was fashioned at the pre-selected site in the right mid-quad- rant. The patient made an uneventful postoper- ative recovery and was discharged on the tenth postoperative day.

FIGURE 4. Schema of fused “cake” kidney overly- ing bifurcation of aorta and vena cava; left portion of ileal segment positioned behind stgmoid colon to reach short left ureter.

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normal position is impaired by the retroperito- neal structures, During ascent, the normal kid- ney receives its blood supply first from the mid- dle sacral artery, then the iliac, and finally from the aorta. When the kidney stays in the pelvis, its blood supply is usually derived from the ter- minal aorta or the iliac arteries. Grossly the “cake” kidney has a flat smooth posterior sur- face and a lobulated anterior surface.3 Histolog- ically the fused pelvic kidney shows immature glomeruli, cystic changes, and enlarged dilated tubules6

Cystectomy in the presence of a fused pelvic kidney is complicated by problems of access, the need for great care in preserving the aber- rant renal vasculature when performing the lymph node dissection, and the short ureters.

During the operation the kidney was rela- tively fixed, but there was sufficient access to the pelvis. Meticulous care in performing the lymph node dissection is necessary since the blood supply to this kidney arose from the iliac arteries. The short ureters presented the

greatest challenge. Ureterosigmoidostomy would have been the easiest solution, but a di- lated left ureter precluded its utilization, Other diversion possibilities included an isolated sig- moid conduit or an ileopyelostomy. The long il- eal loop was chosen bringing it through the sig- moid mesentery. This gave a satisfactory tension-free enteroureterostomy.

956 Court Avenue, Box 10 Memphis, Tennessee 38163

(DR. SOLOWAY)

1. Silverberg E: Cancer statistics, Cancer 31: 13 (1981). 2. GlennJF: Fused pelvic kidney, J Urol80: 7 (1958). 3. Shiller WR, and Wiswell OB: A fused pelvic (cake) kidney,

ibid 78: 9 (1957). 4. Rubenstein M, Meyer R, and Bernstein J: Congenital abnor-

malities of the urinary system. I. A postmortem survey of develop- mental anomalies and acquired congenital lesions in a children’s hospital, J Pediatr 57: 356 (1961).

5. Kelalis PP, Malek RS, and Segura JW: Observations on renal ectopia and fusion in children, J Urol 110: 588 (1973).

6. McCrae LE: Congenital solitary pelvic kidney, ibid 48: 58 (1942).

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