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Ureteropelvic Junction Obstruction Secondary to Periureteral Lipoma
0022-5347/94/1511-0150$03.00/0 THE JOURNAL OF UROLOGY Copyright© 1994 by AMERICAN UROLOGICAL ASSOCIATION, INC.
Vol. 151, 150-151, January 1994 Printed in U.S.A.
URETEROPELVIC JUNCTION OBSTRUCTION SECONDARY TO PERIURETERAL LIPOMA ERIC M. SMITH
AND
MARTIN I. RESNICK
From the Department of Urology, Case Western Reserve University School of Medicine, Cleveland, Ohio
ABSTRACT
We report a unique case of extrinsic ureteral obstruction secondary to a periureteral lipoma discovered during pyeloplasty for an apparent ureteropelvic junction obstruction. We discuss the importance of preoperative recognition of rare extrinsic causes of ureteropelvic junction obstruction. KEY WORDS:
kidney, ureteral obstruction, ureteral neoplasms, lipoma
Extrinsic obstruction of the ureter is a common urological condition with significant morbidity that may result from a number of benign and malignant processes. Primary retroperitoneal tumor is a rare cause of extrinsic ureteral obstruction. 1 To our knowledge we report the first case of ureteropelvic junction obstruction secondary to periureteral lipoma.
DISCUSSION
CASE REPORT
A 32-year-old man presented with a 2-month history of intermittent right flank pain and gross hematuria with passage of several stones. Medical history was remarkable for stone passage 4 years previously. Excretory urography (IVP) revealed an apparent ureteropelvic junction obstruction with multiple associated stones (fig. 1). Although a percutaneous approach was considered, open pyeloplasty with stone extraction was recommended because of the suspected high insertion of the ureter on the renal pelvis. The right renal pelvis and ureter were identified through a flank incision. Findings included a dilated renal pelvis with a well encapsulated 3.0 x 3.0 x 2.5 cm. lipomatous mass surrounding and compressing the right ureter (fig. 2). Simple excision of the lesion was not possible because it was adherent to the ureter. Therefore, the segment of compressed ureter was excised along with the mass. Frozen section demonstrated a benign lesion. All stones were removed from the renal pelvis and dismembered pyeloplasty was performed. Convalescence was uneventful. Pathological evaluation was consistent with a benign encapsulated lipoma surrounding the proximal ureter. Accepted for publication June 18, 1993.
Extrinsic obstruction of the ureter may occur secondary to a variety of retroperitoneal processes, including vascular lesions, benign and malignant pelvic masses, pelvic inflammatory conditions, iatrogenic ligation injuries, diseases of the gastrointestinal tract, primary disorders of the retroperitoneum such as retroperitoneal fibrosis, radiation fibrosis, retroperitoneal infection or hemorrhage and retroperitoneal masses. Lymphomas account for a third of the retroperitoneal tumors causing ureteral obstruction. Neuroblastomas, sarcomas, neurofibromas, adenomas, cysts, metastatic lesions, pheochromocytomas and retroperitoneal xanthogranulomas comprise the remainder of these cases. 1 A review of the literature demonstrated no previous report of extrinsic ureteropelvic junction obstruction caused by a simple lipoma. Lipomas are common lesions found principally in the subcutaneous tissues of the neck and trunk, although they can also occur in the retroperitoneum, skeletal muscle, mediastinum and gastrointestinal tract. 2 They usually present as a single, painless mass that typically measures 1 to 5 cm. but may grow as large as 60 cm. Grossly lipomas are smooth, encapsulated masses that are yellow to orange on cut section. Microscopically they are composed of lobules of adipose tissue separated by thin fibrous septa. It is generally believed that malignant degeneration of lipoma to liposarcoma does not occur.3 In this case a benign retroperitoneal tumor mimicked a simple ureteropelvic junction obstruction. The tumor was recognized only because dismembered pyeloplasty was performed, although retrospective review of the preoperative IVP showed
FIG. 1. Preoperative IVP is consistent with right ureteropelvic junction obstruction. A, scout film. B, 15-minute film
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URETEROPELVIC JUNCTJ:ON OBSTRUCTION DUE TO PERWRETERAL LIPOtvIA
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that a mass effect was present. If endopyelotomy had been done the retroperitoneal tumor probably would not have been discovered. Whether this approach would have been efficacious remains unknown. While we do not advocate routine computerized tomography or magnetic resonance imaging in patients undergoing endopyelotomy, the possibility that a ureteropelvic junction obstruction may be secondary to an extrinsic mass should always be considered. Although the lesion in this case fortunately was benign, our experience with this previously unreported cause of extrinsic ureteral obstruction should serve as a reminder that clinical ureteropelvic junction obstruction may rarely be associated with retroperitoneal neoplasms.
REFERENCES 1. Resnick, M. I. and Kursh, E. D.: Extrinsic obstruction of the ureter.
FIG. 2. A, gross specimen. Stent passes through excised segment of ureter. B, bivalved gross specimen. Arrows indicate ureter.
In: Campbell's Urology, 6th ed. Edited by P. C. Walsh, A. B. Retik, T. A. Stamey and E. D. Vaughan, Jr. Philadelphia: W. B. Saunders Co., vol. 1, chapt. 12, pp. 533-570, 1992. 2. Robbins S. S., Cotran, R. S. and Kumar, V.: Pathologic Basis of Disease, 3rd ed. Philadelphia: W. B. Saunders Co., p. 270, 1984. 3. Kryiakos, M.: Tumors and tumorlike conditions of the soft tissue. In: Anderson's Pathology. Edited by J.M. Kissane. Philadelphia: C. V. Mosby Co., vol. 2, pp. 1838-1921, 1990.
Vol. 151, 150-151, January 1994 Printed in U.S.A.
URETEROPELVIC JUNCTION OBSTRUCTION SECONDARY TO PERIURETERAL LIPOMA ERIC M. SMITH
AND
MARTIN I. RESNICK
From the Department of Urology, Case Western Reserve University School of Medicine, Cleveland, Ohio
ABSTRACT
We report a unique case of extrinsic ureteral obstruction secondary to a periureteral lipoma discovered during pyeloplasty for an apparent ureteropelvic junction obstruction. We discuss the importance of preoperative recognition of rare extrinsic causes of ureteropelvic junction obstruction. KEY WORDS:
kidney, ureteral obstruction, ureteral neoplasms, lipoma
Extrinsic obstruction of the ureter is a common urological condition with significant morbidity that may result from a number of benign and malignant processes. Primary retroperitoneal tumor is a rare cause of extrinsic ureteral obstruction. 1 To our knowledge we report the first case of ureteropelvic junction obstruction secondary to periureteral lipoma.
DISCUSSION
CASE REPORT
A 32-year-old man presented with a 2-month history of intermittent right flank pain and gross hematuria with passage of several stones. Medical history was remarkable for stone passage 4 years previously. Excretory urography (IVP) revealed an apparent ureteropelvic junction obstruction with multiple associated stones (fig. 1). Although a percutaneous approach was considered, open pyeloplasty with stone extraction was recommended because of the suspected high insertion of the ureter on the renal pelvis. The right renal pelvis and ureter were identified through a flank incision. Findings included a dilated renal pelvis with a well encapsulated 3.0 x 3.0 x 2.5 cm. lipomatous mass surrounding and compressing the right ureter (fig. 2). Simple excision of the lesion was not possible because it was adherent to the ureter. Therefore, the segment of compressed ureter was excised along with the mass. Frozen section demonstrated a benign lesion. All stones were removed from the renal pelvis and dismembered pyeloplasty was performed. Convalescence was uneventful. Pathological evaluation was consistent with a benign encapsulated lipoma surrounding the proximal ureter. Accepted for publication June 18, 1993.
Extrinsic obstruction of the ureter may occur secondary to a variety of retroperitoneal processes, including vascular lesions, benign and malignant pelvic masses, pelvic inflammatory conditions, iatrogenic ligation injuries, diseases of the gastrointestinal tract, primary disorders of the retroperitoneum such as retroperitoneal fibrosis, radiation fibrosis, retroperitoneal infection or hemorrhage and retroperitoneal masses. Lymphomas account for a third of the retroperitoneal tumors causing ureteral obstruction. Neuroblastomas, sarcomas, neurofibromas, adenomas, cysts, metastatic lesions, pheochromocytomas and retroperitoneal xanthogranulomas comprise the remainder of these cases. 1 A review of the literature demonstrated no previous report of extrinsic ureteropelvic junction obstruction caused by a simple lipoma. Lipomas are common lesions found principally in the subcutaneous tissues of the neck and trunk, although they can also occur in the retroperitoneum, skeletal muscle, mediastinum and gastrointestinal tract. 2 They usually present as a single, painless mass that typically measures 1 to 5 cm. but may grow as large as 60 cm. Grossly lipomas are smooth, encapsulated masses that are yellow to orange on cut section. Microscopically they are composed of lobules of adipose tissue separated by thin fibrous septa. It is generally believed that malignant degeneration of lipoma to liposarcoma does not occur.3 In this case a benign retroperitoneal tumor mimicked a simple ureteropelvic junction obstruction. The tumor was recognized only because dismembered pyeloplasty was performed, although retrospective review of the preoperative IVP showed
FIG. 1. Preoperative IVP is consistent with right ureteropelvic junction obstruction. A, scout film. B, 15-minute film
150
URETEROPELVIC JUNCTJ:ON OBSTRUCTION DUE TO PERWRETERAL LIPOtvIA
151
that a mass effect was present. If endopyelotomy had been done the retroperitoneal tumor probably would not have been discovered. Whether this approach would have been efficacious remains unknown. While we do not advocate routine computerized tomography or magnetic resonance imaging in patients undergoing endopyelotomy, the possibility that a ureteropelvic junction obstruction may be secondary to an extrinsic mass should always be considered. Although the lesion in this case fortunately was benign, our experience with this previously unreported cause of extrinsic ureteral obstruction should serve as a reminder that clinical ureteropelvic junction obstruction may rarely be associated with retroperitoneal neoplasms.
REFERENCES 1. Resnick, M. I. and Kursh, E. D.: Extrinsic obstruction of the ureter.
FIG. 2. A, gross specimen. Stent passes through excised segment of ureter. B, bivalved gross specimen. Arrows indicate ureter.
In: Campbell's Urology, 6th ed. Edited by P. C. Walsh, A. B. Retik, T. A. Stamey and E. D. Vaughan, Jr. Philadelphia: W. B. Saunders Co., vol. 1, chapt. 12, pp. 533-570, 1992. 2. Robbins S. S., Cotran, R. S. and Kumar, V.: Pathologic Basis of Disease, 3rd ed. Philadelphia: W. B. Saunders Co., p. 270, 1984. 3. Kryiakos, M.: Tumors and tumorlike conditions of the soft tissue. In: Anderson's Pathology. Edited by J.M. Kissane. Philadelphia: C. V. Mosby Co., vol. 2, pp. 1838-1921, 1990.