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CASE REPORTS

Nephrogenic Adenoma of the Renal Pelvis L. MARTINEZ-PINEIR0,L. HIDALGO, M. L. PICAZO, J. M . COZAR and J. A. MARTINEZ-PIAEIRO, Department of Urology and Pathology, La Paz Hospital, Madrid, Spain

Case Report In October 1982 a 36-year-old man underwent radical cystectomy and ileocaecal conduit urinary diversion for a transitional cell bladder tumour (pT4a G3 pNO MO), receiving adjuvant chemotherapy with methotrexate afterwards (1 g/m2/21days, 19 courses). During 1985 and 1986 he developed multiple infective renal calculi which, in spite of local chemolysis with Renacidin, led to 2 bilateral percutaneous nephrolithotomies. Four months after the first percutaneous procedure a stricture of the left pelviureteric junction (PUJ) was detected and a percutaneous nephrostomy performed (Fig. 1). The patient refused further surgery to correct the PUJ stricture until November 1988, when he underwent another left percutaneous nephrolithotomy and endopyelotomy. During the procedure a small papillary tumour, situated at the PUJ and the anterior pelvic wall, was seen and biopsed. Histology revealed a nephrogenic adenoma of the renal pelvis (Fig. 2).

Comment Nephrogenic adenoma is an uncommon lesion of the urothelium, first described by Davis in 1949 and subsequently characterised in detail and named by Friedman and Kuhlenbeck in 1950. It has been

Fig. 2 Nephrogenic adenoma. Papillary processes covered by a single layer of cuboidal epithelium together with small tubular structures are seen within the lamina propria. (H and E x 25).

encountered along the entire urinary tract, although its most frequent anatomical site is the bladder (72%). Other sites are less frequently affected: ureter 8%, urethra 9%, renal pelvis 11% (McIntire et al., 1987). It is thought to arise as an immature metaplastic response of transitional epithelium to chronic inflammation and is considered benign, although in many instances it appears associated with a bladder carcinoma. Various predisposing factors have been proposed: congenital factors, chronic cystitis, urinary infection, calculi, previous surgery, renal transplant immunosuppression, bladder cancer, intravesical chemotherapy and immunotherapy, malakoplakia and diverticula. In our case several of these factors may have been at work. The frequent papillary appearance and the microscopic resemblance to clear cell adenocarcinoma of the urinary tract make the histological distinction essential in the diagnosis and treatment.

References

Fig. 1 Left antegrade pyelogram showing left PUJ stricture, the ileocaecal conduit and reflux to the right urinary system. No filling defect can be seen in the left renal pelvis.

Davis, T. A. (1949). Hamartoma of the urinary bladder. Northwest. Med., 48, 182-185. Friedman, N. B. and Kuhlenbeck, H. (1950). Adenomatoid tumors of the bladder reproducing renal structures (nephrogenic adenomas). J . Urol., 64,657-670. McIntire, T. L., Soloway, M. S. and Murphy, W. M. (1987). Nephrogenic adenoma. Urology, 29,237-241. Requests for reprints to: L. Martinez-Pifieiro, Avda. San Luis 95,3G, 28033 Madrid, Spain.

Nephrogenic adenoma of the renal pelvis.

101 CASE REPORTS Nephrogenic Adenoma of the Renal Pelvis L. MARTINEZ-PINEIR0,L. HIDALGO, M. L. PICAZO, J. M . COZAR and J. A. MARTINEZ-PIAEIRO, Depa...
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