Benign Retroperitoneal Schwannoma Mimicking Adrenal Mass

FARID DADKHAH*, MOHAMMADREZA SALIMI, ALI KAVIANI

Department of Urology, Shaheed Modarress Hospital, Shaheed Beheshti University of 

medical Sciences, Tehran, Iran

KEY WORDS: adrenal mass, retroperitoneal tumor, schwannoma, diagnosis

49

Urology Journal

UNRC/IUA

Vol. 2, No. 1, 49-51 Winter 2005

Printed in IRAN

Benign retroperitoneal schwannoma is a rare

tumor originating from the schwann cells in the

myelinated neural sheath and mostly manifested

as an adrenal mass.(1-7) However, there are

reports of developing of this tumor within or in

front of psoas muscle(8) or other parts of the

body. We report a benign retroperitoneal

schwannoma, incidentally detected through

imaging, mimicking an adrenal mass.

Case Report

A 57-year-old female, weighed 85 kg at

presentation, was referred to our center with a

large abdominal mass, which was incidentally

detected in right adrenal site through imaging.

No history of right flank pain, gross hematuria,

sweating, flushing, or tachycardia was reported.

On physical examination, the mass was not

palpable in the right flank.

Moreover, microscopic hematuria was not seen

in the conducted tests, and laboratory studies for

pheochromocytoma were negative. CT scan

showed a large right adrenal mass with low

density central area, indicating central necrosis

together with enhanced septation (fig. 1). MRI

demonstrated a hyperintense lesion in T1

weighted image, which is seen in figure 2A,

attached to the kidney, and in figure 2B, apart

from the kidney with adrenal origin. Right

adrenal gland is seen in figure 2A. The

hyperintense lesion was seen in T2 weighted

image, as well (fig. 2C).

The patient underwent exploration with the

preoperative differential diagnoses of adrenal

mass, retroperitoneal mass, and renal mass,

respectively. A large mass apart from kidney was

seen that had pushed the adrenal gland upward

and could have been easily separated from the

kidney and adrenal gland. The tumor was drained

via a vein at a size of renal vein which was

directly connected to inferior vena cava.  The

mass, measured 6 × 8 ×12 cm, was removed

(fig. 3A). In figure 3B, necrotic and cystic

changes in central areas are seen through a cut

section from the mass. Histologic examination

confirmed that this giant tumor was a benign

retroperitoneal schwannoma, predominantly

Anton A type (fig 4).  In 1-year follow-up, no

recurrence was observed and the patient had no

complication.

Discussion

Retroperitoneal schwannoma is a rare tumor

originating from the schwann cells in the

myelinated sheath of nerves.(1) It has been mostly

reported a benign tumor.(1-7)

Received January 2004

Accepted June 2004

*Corresponding author: Shaheed Modarress Hospital,

Saadat Abad, Tehran, Iran.

E-mail: dr_fdadkhah@yahoo.com.

FIG. 1. Abdominal CT scan showed a large mass with

central necrosis at the right adrenal area.



In a study carried out in Japan, of all the cases

of schwannoma 94 (72.3%) were benign and 36

(27.7%) were malignant.(2)

Schwannoma develops as an adrenal mass, as

reported in most cases.(1-7) Symptomatic patients

have only vague flank pain. Due to central

necrosis, this tumor has a low density(2) or

internal cystic schema(3) in CT scan. However,

although the presence of cystic schema is highly

indicative of schwannoma, this is not necessary

for diagnosis.(3) Exploration is often required for

diagnosis of this tumor, since mere imaging

would not be sufficient in most cases.(5)

In our case, an internal cystic schema was seen.

Although the mass was separate from adrenal

gland and kidney in most CT scan cuts, in some

other cuts the mass seemed to have completely

adrenal origin. Also, it seemed that there was a

complete adhesion to kidney, even originating

from the kidney capsule. As a result, we could not

determine its real origin preoperatively. During

Benign Retroperitoneal Schwannoma50

FIG. 2. MRI, A. T1 weighted image: a hyperintense tumor

in the upper pole of the right kidney, B. T1 weighted

image: the tumor appears to be separate from the kidney.

C. T2 weighted image: the tumor is hyperintense.

FIG. 3. A. the extracted tumor, B. the tumor,

longitudinally incised.

A

C

B

A

B



Dadkhah et al 51

exploration, the mass was completely separated

from kidney and adrenal gland, and our diagnosis

was retroperitoneal mass. Finally, pathologic

diagnosis of benign schwannoma confirmed its

retroperitoneal nature.

References

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Hinyokika Kiyo. 1984;30:1045-51. Japanese

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A, et al. [Benign adrenal schwannoma]. Arch Esp Urol.

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Benign retroperitoneal schwannoma mimicking an

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FIG. 4. Pathologic view of the tumor texture, a benign

retroperitoneal schwannoma, predominantly Anton A type