T h e benign appearance of Wilms' tumor 1

Thomas Maatman, D.O. Robert Kay, M.D.

Intrarenal masses in children are uncommon, with Wilms' tu-mor the most prevalent of these. Two cases are presented in which the preoperative evaluation of renal masses was highly suggestive of benign disease, renal abscess, and multilocular cyst. Surgical exploration was performed in both patients, and Wilms' tumor was found and treated successfully with radical nephrectomy. These two cases emphasize the need for surgical exploration to accurately diagnose intrarenal masses in children even when all diagnostic modalities are suggestive, but not confirmatory, of benign disease.

Index terms: Kidney neoplasms • Nephroblastoma • Wilms' tumor

Cleve Clin Q 50:279-282, Fall 1983

1 D e p a r t m e n t of Pediatr ic and Adolescent Medicine, Section of Pedia t r ic Urology, D e p a r t m e n t of Urology, T h e Cleveland Clinic Founda t ion . Submi t t ed fo r pub-lication Apri l 1983; accepted May 1983.

Malignant renal neoplasms of childhood are uncom-mon.1 Wilms' tumor is the most common of these, with 450 cases reported per year in the United States. The correct diagnosis is essential to avoid progression of this fatal malignant disease, and, conversely, to avoid inappro-priate treatment with radiation and chemotherapy in chil-dren with benign disease. We present two cases in which all preoperative studies indicated benign renal disease, renal abscess, and multilocular cysts. However, when sur-gery was performed to accurately diagnose the intrarenal mass, malignant disease was found.

Case reports Case 1. An eight-year-old boy was re fe r red to T h e Cleveland Clinic

Foundat ion for evaluation of a possible right renal abscess. Four months be fo re admission, he was seen at his local hospital with r ight flank pain,

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Fig. 1. Excre tory u r o g r a m displaying a mass in the lower pole of the right kidney with stippled calcification. Fig. 2. Renal ang iog ram d e m o n s t r a t i n g a 4 x 4-cm mass in the lower pole of the right kidney.

fever , chills, gross hematur i a , and pro te inur ia . A diagnosis of acute pyelonephri t is was made , and he was t rea ted with in t ravenous antibiotics with the resolut ion of symptoms. Fever , pain, and hematur ia r e tu rned , a n d his condit ion was reevaluated. An excre tory u rog ram was obta ined displaying a mass in the lower pole of the right kidney with calcifica-tions (Fig. 1). He was r e f e r r e d to the Cleveland Clinic for f u r t h e r evaluation and t r ea tmen t . O n admission ur ine cul-tu re a n d sensitivities for aerobes and acid-fast bacillus were negative. Chest r oen tgenogram revealed a left hilar mass suggestive of g ranu lomatous disease. C o m p u t e d tomogra-phy (CT) and u l t rasonography of the kidney conf i rmed the p resence of a mass in the lower pole of the right kidney, which was suggestive of a renal abscess, but not conf i rma-tory. Renal angiography revealed a 4 X 4-cm avascular mass in the lower pole of the right kidney (Fig. 2). Radiologic diagnosis was most likely that of a renal abscess. Because Wilms' t u m o r could not be completely exc luded , the pat ient was taken to the opera t ing room. Indura t ion in the lower pole of the right kidney was noted , a n d a radical nephrec-tomy was p e r f o r m e d . Pathologic r e p o r t revealed a 3.5-cm Wilms' t u m o r invading the wall of the renal vein and the renal sinus classified as a stage II Wilms' t u m o r . Postopera-tively the pat ient was t rea ted with radia t ion therapy and chemothe rapy and did well.

Case 2. A three-year-old boy was r e f e r r e d to T h e Cleve-land Clinic Foundat ion for evaluation of an asymptomatic right u p p e r quadran t mass that was de tec ted on rout ine physical examina t ion . F.xcretory u r o g r a m revealed an intra-renal mass of the right kidney with dilatation of the collect-ing system (Fig. 3). A C T scan of the right kidney revealed a large soft-tissue mass located in the an te r io r por t ion of the r ight kidney with i r regular areas of decreased a t tenuat ion (Fig. 4). U l t rasound revealed a solid complex, cystic mass. Angiography demons t ra t ed displacement of vessels, but no pathologic vessels were visualized (Fig. 5). Preoperat ive eval-uation was believed to be compat ible with a multi locular cyst. Because of the possible risk of an in t rarenal mass in a pat ient of this age, surgical explorat ion was pe r fo rmed . A stage I Wilms' t u m o r was discovered, and a right radical nephrec tomy was p e r f o r m e d . Postoperatively the patient did well, and received chemotherapy as par t of the National Wilms' T u m o r Study G r o u p protocol and current ly is with-out evidence of disease.

Discussion T h e preoperative diagnosis of Wilms' tumor is

usually easily determined. However, in the Na-tional Wilms' T u m o r Study I, 30 of 606 (5%)

Fall 1983 Benign appearance of Wilms' tumor 281

Fig. 3. Excretory u r o g r a m reveal ing di la tat ion a n d dis tor t ion of t h e right renal calyces.

Fig . 4. C T scan of the a b d o m e n d e m o n s t r a t i n g right renal mass with cystic c o m p o n e n t .

patients had incorrect preoperative diagnoses and were ultimately proved not to have Wilms' tumor.2 In our two cases, the preoperative eval-uation suggested benign disease, and only sur-gical exploration confirmed the presence of ma-lignant disease.

The diagnosis of Wilms' tumor is usually made on the basis of presenting symptoms, physical examination, and radiological findings. Excre-tory urography can usually detect a renal mass,

Fig. 5. Right renal ang iogram displaying an avascular mass in t h e r ight kidney.

and other studies can confirm and clearly define the mass. Ultrasound a n d / o r C T can determine the consistency, and help define the mass as solid or cystic. Cystic appearance usually suggests mul-ticystic or polycystic kidney; however, tumor must be considered in selected cases. Necrosis and hemorrhage may lead to a cystic appearance of the tumor mass. ' In addition, tumors have been reported in multicystic kidney.4 '

The necessity of arteriography in the diagnosis of Wilms' tumor remains controversial. How-ever, it may be helpful in difficult diagnostic cases, with abnormal vascularity existing in 85% to 90% of all Wilms' tumors." The absence of pathologic vascularity, however, does not rule out Wilms' tumor as evidenced in our two cases.

Needle biopsy of selected renal masses has been used extensively in adults.' The risk of disrupting the tumor and having local implantation is rare.' In children, the procedure is rarely used, as the diagnosis is not usually in doubt, and a needle biopsy may potentially contaminate the local area, requiring postoperative radiation. In addi-

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tion, the finding of tumor cells would be confir-matory, but a negative aspiration does not rule out the presence of a potentially malignant pro-cess. As in our two cases, if the diagnosis is in doubt, surgical exploration may be necessary as both a diagnostic and therapeutic step. The fail-ure to correctly diagnose the renal mass in a child may allow fatal progression of the disease, and all diagnostic modalities from an excretory uro-gram to surgery may be required and must be used in selected cases.

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U S ch i ld ren . J Ped ia t r 1975; 8 6 : 2 5 4 - 2 5 8 .

2. Ehrl ich RM, B l o o m b e r g SD, Gyepes M T , e t a l . Wilms t u m o r , misd iagnosed preopera t ive ly ; a review of 19 Nat ional Wilms t u m o r study I cases. J Uro l 1979; 1 2 2 : 7 9 0 - 7 9 2 .

3. Bloom DA, Brosman S. T h e multicystic kidney. J Uro l 1978; 1 2 0 : 2 1 1 - 2 1 5 .

4. R a f f e n s p e r g e r J, Abous le iman A. Abdomina l masses in chil-d r e n u n d e r o n e year of age . S u r g e r y 1968; 6 3 : 5 1 4 - 5 2 1 .

5. Uson AC, Del Rosar io C, Melicow MM. Wilms t u m o r in association with cystic rena l disease: r e p o r t of two cases. J Uro l 1 9 6 0 ; 8 3 : 2 6 2 - 2 6 6 .

6. Clark RE, Moss AA, D e L o r i m i e r AA, Palubinskas AJ. Ar te-r iog raphy of Wilms ' t u m o r . AJR 1971; 1 1 3 : 4 7 6 - 4 9 0 .

7. Cede r lo f S. Assessment of a symptomat ic space occupying le-sions of t he k idney. Acta Ch i r Scand 1979; 1 4 5 : 1 8 5 - 1 8 9 .

8. G ibbons RP, Bush W H J r , B u r n e t t LL. Need l e t ract seeding fo l lowing aspira t ion of rena l cell ca rc inoma. J Uro l 1977; 1 1 8 : 8 6 5 - 8 6 7 .