Villous Adenoma in the Native Kidney of a Renal Transplant Recipient

Abstract

This patient presented in 1976 with a creatinine of 2.8 mg/dL, and bilateral renal and ureteral stones requiring lithotomy. In 1983, he developed renal failure requiring hemodialysis. He received a living renal transplant in 1986, and was maintained on prednisone and cyclosporine immunosuppression. Routine ultrasonography in 1997 revealed hydronephrosis of the native right kidney. Follow-up studies showed a progressive increase in the size of the kidney and the development of cystic disease. Multiple urine cytologies were negative for malignant cells. Urine cultures were persistently positive for Escherichia coli and the patient was treated with multiple courses of antibiotics. In June 2003, the patient complained of back pain and weight loss. Sonography showed an enlarged, multiloculated cystic mass in the right renal fossa. CT scanning was notable for a new right hydroureter. He was admitted for an elective right nephrectomy. Gross examination revealed a 35× 20× 3 cm hydronephrotic kidney with multiple areas of necrosis and hemorrhage, and multiple mucosal masses, ranging from 0.5 to 2.5 cm, with one attached at the distal ureter lumen causing obstruction. Microscopy showed intestinal metaplasia throughout the renal pelvis and ureter, and multiple villous adenomas arising from metaplastic mucosa (Fig. 1), two with focal high grade dysplasia, and one with superficial stromal invasion. The mass in the distal ureter was also a villous adenoma. A swab of the kidney grew the same E. coli as in the previous positive urine cultures.FIGURE 1.: Example of an intestinal-type adenomatous polyp arising from metaplastic epitheliuam lining the renal pelvis (original magnification, 4×). Lower right hand corner insert shows intestinal-type epithelium at 40× magnification.A colonoscopy was performed to rule out metastasis from a colonic adenocarcinoma. Four polyps were identified and removed, all tubular adenomas. No villous adenomas or carcinomas were found. Intestinal-type villous adenoma is a rare tumor of the urinary tract. Patients typically present with hematuria, mucusuria, and irritative symptoms (1, 2). There is no predilection for age or sex (1–4). Villous adenomas of the urinary tract are identical to their colonic counterparts, with rounded projections of pseudostratified columnar epithelium and mucin producing cells (1, 2). Urothelium may undergo intestinal metaplasia in response to chronic irritation, such as from stones, chemical injury, or chronic inflammation (1). Our patient's multiple stones, urological procedures, and chronic infections may have led to persistent irritation of the renal pelvis and ureter, with intestinal metaplasia and subsequent villous adenoma development. Resection is curative, unless it is associated with underlying infiltrating adenocarcinoma. In two case series reviewing a combined 41 patients, none of the patients with isolated villous adenoma or with associated in situ adenocarcinoma had recurrence after local excision (1, 2). Intestinal-type villous adenomas of the urinary tract are most commonly found in the bladder, arising from metaplastic epithelium. In a series of 23 patients, one case was found in the ureter, and another in the ureteral orifice (1). Only one case of villous adenoma involving the renal pelvis has been reported (5). Our patient is unique in that he had multiple tumors involving the renal pelvis and ureter. This is also the first case that we could find of villous adenoma of the urinary system developing in a renal transplant patient. Krista G. Fudge Daniel Glicklich Ladan Golestaneh Division of Nephrology Department of Medicine Albert Einstein College of Medicine Montefiore Medical Center Bronx, NY James Pullman Department of Pathology Albert Einstein College of Medicine Montefiore Medical Center Bronx, NY