EXTRA-ADRENAL PHEOCHROMOCYTOMA:: A CAUSE OF URETERAL OBSTRUCTION

0022-5347/00/1631-0264/0 THE JOURNAL OF UROLOGY® Copyright © 2000 by AMERICAN UROLOGICAL ASSOCIATION, INC.®

Vol. 163, 264, January 2000 Printed in U.S.A.

EXTRA-ADRENAL PHEOCHROMOCYTOMA: A CAUSE OF URETERAL OBSTRUCTION SUBHASH YADAV, S. K. SINGH, S. K. SHARMA

AND

P. K. PURI

From the Affiliation Department of Urology, Postgraduate Institute of Medical Education and Research, Chandigarh, India KEY WORDS: pheochromocytoma, ureteral obstruction, ureter

Extra-adrenal pheochromocytoma constitutes 15% of adult and 30% of pediatric pheochromocytomas.1 It most commonly occurs in the second or third decade of life with a slight male preponderance.2 Arising wherever chromaffin cells of the paraganglionic system are located (from skull base to bladder), more than 85% of these tumors occur in the retroperitoneum.3 In rare cases ureteral obstruction can occur if the tumor grows in the vicinity of the ureter. To our knowledge only 2 such cases have been reported to date.3 We report the third case of ureteral obstruction caused by extra-adrenal pheochromocytoma. CASE REPORT

A. S., a 16-year-old boy, presented with a 1-year history of episodic headaches, palpitation, paroxysmal hypertension and right flank pain. Symptoms precipitated during the basketball games in which he played. Blood pressure was 190/114 mm. Hg. Abdominal examination was unremarkable. Fundoscopy revealed grade II hypertensive changes. Routine evaluation demonstrated normal hematocrit and renal function test. The 24-hour epinephrine was 68 mg. (normal 12 to 85), norepinephrine 722 mg. (normal 85 to 400) and vanillylmandelic acid 11.2 mg. (normal 1.6 to 6.5). Ultrasound showed right hydroureteronephrosis and a heterogeneous 36 3 24 mm. mass in the right paracaval region, which was hypervascular on Doppler study. Excretory urography and retrograde pyelography revealed ureteral obstruction at the level of L4 vertebrae and hydroureteronephrosis. A soft tissue 31 3 21 3 20 mm. mass in the right paracaval region was evident on computerized tomography (CT) with contrast enhancement (fig. 1). Preoperatively, the patient started taking 10 mg. phenoxybenzamine 3 times daily to control hypertension and 4 units of plasma were transfused for volume expansion. The tumor, which encased the ureter, was approached through a midline transperitoneal incision and excised along with the involved segment of ureter (fig. 2). Continuity of the ureter was established with spatulated end-to-end anastomosis. Convalescence was uneventful. Histopathological examAccepted for publication August 27, 1999.

FIG. 2. Entrapment of ureter (U) by tumor (T)

ination of the tumor confirmed pheochromocytoma infiltrating ureteral adventitia. At 14-month followup the patient was well and normotensive, and urinary catecholamine levels were within normal limits. DISCUSSION

The majority of extra-adrenal pheochromocytomas occurring below the diaphragm are functional, and have affected the superior and inferior para-aortic areas, near the origin of the inferior mesenteric artery and aortic bifurcation (organ of Zuckerkandl). Failure of involution of chromaffin tissue leads to development of pheochromocytoma at these sites. Most of the symptoms of extra-adrenal pheochromocytoma are related to excessive secretion of catecholamines, primarily norepinephrine. However, symptoms may result from tumor compression of adjacent structures. Obstruction of the right renal unit was the cause of flank pain in our case. Aggravation of symptoms during basketball games was probably due to stretching of the tumor caused by hyperextension of the spine, resulting in the sudden release of catecholamines. The diagnosis of extra-adrenal pheochromocytoma is established by biochemical examination of plasma and urinary catecholamines and their metabolites. Precise localization is important for safe excision, and CT, 131iodine scintigraphy and magnetic resonance imaging are useful modalities.1, 2 Preoperative and intraoperative management is the same as for adrenal pheochromocytoma but one should explore the retroperitoneum to detect multifocal extra-adrenal pheochromocytoma. The chances of malignancy are 20% to 40% in patients with extra-adrenal pheochromocytoma.2 Local invasion per se does not indicate that the tumor is malignant.1 However, due to high risk of recurrence and metastasis these patients need lifelong followup.1 REFERENCES

1. Whalen, R. K., Althausen, A. F. and Daniels, G. H.: Extraadrenal pheochromocytoma. J Urol, 147: 1, 1992. 2. Goldfarb, D. A., Novick, A. C., Bravo, E. L. et al: Experience with extra-adrenal pheochromocytoma. J Urol, 142: 931, 1989. 3. Atiyeh, B. A., Barakat, A. J. and Abumrad, N. N.: Extra-adrenal pheochromocytoma. J Nephrol, 10: 25, 1997.

FIG. 1. CT shows mass anterior to stented ureter 264