Multiple Retroperitoneal Schwannomas: Case Report and Review of the Literature

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Vol. 151, 413-416, Febrnary 1994

THE JOURNAL OF UROLOGY

Copyright© 1994 by AMERICAN UROLOGICAL ASSOCIATION, INC.

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MULTIPLE RETROPERITONEAL SCHWANNOMAS: CASE REPORT AND REVIEW OF THE LITERATURE LIAM HURLEY, JOHN J. SMITH, III,* CARL R. LARSEN

AND

MARK L. SILVERMAN

From the Departments of Urology, Diagnostic Radiology and Anatomic Pathology, Lahey Clinic, Burlington, Massachusetts

ABSTRACT

We report a rare case of multiple retroperitoneal schwannomas, initially believed to be an adrenal carcinoma with metastasis. These benign tumors were discovered in a patient presenting with vague back pain. Preoperative radiographic and endocrine evaluations suggested a nonfunctioning adrenal tumor. The final diagnosis and its juxta-adrenal origin were confirmed by histological and immunohistochemical studies. A review of the literature on retroperitoneal schwannoma is included. KEY WORDS:

neuroma, acoustic; retroperitoneal space; retroperitoneal neoplasms

Schwannomas account for 1 to 10% of all primary retroperitoneal neoplasms. 1 Most schwannomas are benign; however, malignant tumors have been reported, although they are usually associated with von Recklinghausen's disease. To our knowledge the presentation of juxta-adrenal schwannoma with simultaneous multiple mediastinal masses simulating metastatic adrenal carcinoma is unique. CASE REPORT

A 49-year-old man sought medical attention for a 1-month history of vague back pain. Medical history was unremarkable. Family history was negative for malignant disease or stigmata of von Recklinghausen's neurofibromatosis. A vague fullness in the right upper quadrant was revealed on physical examination. Cutaneous examinations revealed no cafe-au-lait spots, axillary freckles or neurofibromas. Results of ocular and fundoscopic examination were also negative. The hematocrit was 45% and the white blood count was 5.2 X 109/1. with a normal differential count. Results of urinalysis were normal. Chemical evaluation was negative for pheochromocytoma and Cushing's disease. A questionable hilar fullness was revealed on roentgenography of the chest and computerized tomography (CT) demonstrated a low lying 3 x 3.5 x 9 cm. homogeneous chest lesion (fig. 1) and a 1 X 2 cm. paravertebral mass on the right side at the TIO spinal level. No clear-cut relationship to the neural canal or neural foramen was seen. In addition, a 6 X 8 cm. heterogeneous right adrenal mass was found with no definite fat plane between the adrenal glands and kidney (fig. 2). The attenuation of 25 Hounsfield units suggested blood, high proteinaceous fluid or necrotic tissue within this mass without any calcification. Magnetic resonance imaging (MRI) of the abdomen with a Tl-weighted sequence (the patient was claustrophobic and refused additional sequences) demonstrated a well defined large adrenal mass with a definitive fat plane between the presumed adrenal gland and kidney (fig. 3). The right kidney was displaced downward by mass effect. Adrenal carcinoma could not be excluded, with possible metastasis to the chest. A needle biopsy of 1 pulmonary mass under CT guidance demonstrated spindle cells, with the question of neural origin. Venography revealed extrinsic compression of the suprarenal inferior vena cava from the adrenal mass without any evidence of invasion or thrombus (fig. 4). Exploration through a thoracoabdominal incision revealed 3 masses, 2 in the posterior mediastinum and 1 in the suprarenal region. The 2 mediastinal lesions consisted of a 2 cm. mobile Accepted for publication July 23, 1993. * Requests for reprints: Department of Urology, Lahey Clinic, 41 Mall Rd., Burlington, Massachusetts 01805. 413

FIG. 1. CT of chest shows low lying 7 x 4 x 9 cm. homogeneous paravertebral mass.

retrocrural lesion within the sympathetic chain and an 8.5 x 4.5 X 3.5 cm. mass near the right lateral vertebral body at the TlO level. Both masses were easily excised. In addition, an 8.5 X 7.5 X 6 cm. right adrenal mass was completely dissected from the upper pole of the kidney and inferior vena cava. All masses were encapsulated, with no evidence of invasion into the adjacent structures. On macroscopic examination the tumors on cut section were gray and fleshy, with some central cystic degeneration. In fact, a normal but atrophied right adrenal gland was identified and was compressed by this retroperitoneal mass. On microscopic examination, each of the tumors showed bland spindle cells with nuclear palisade Antoni A areas (fig. 5) alternating with more mucoid and less cellular Antoni B areas characteristic of benign schwannoma. DISCUSSION

In the absence ofvon Recklinghausen's disease, the majority of solitary schwannomas are benign. Schwannomas can occur anywhere there is a nerve with Schwann's cells in its sheath. They most commonly involve the cutaneous nerves of the head and neck in 40 to 50% of the patients. The upper extremities, lower extremities and trunk, in decreasing frequency, make up

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FIG. 2. CT reveals 6 X 8 cm. heterogenous right adrenal mass

FIG. 4. Venography reveals extrinsic compression of suprarenal inferior vena cava from adrenal mass.

FIG. 3. MRI of abdomen demonstrates large adrenal mass

most of the remaining sites. They are rarely found in the retroperitoneum and, if so, are usually associated with von Recklinghausen's disease. 2 The true incidence of benign schwannoma is difficult to establish because most series include this tumor with neurofibroma. Takatera et al reported on 133 retroperitoneal schwannomas (96 benign and 37 malignant). 3 Steers et al reviewed the literature and found 42 cases of retroperitoneal neurilemomas or schwannomas. 2 However, in a series of 688 primary retroperitoneal tumors Scanlan found only a 1% incidence of schwannoma. 4 Using the combined evidence contained in all of these studies, it can be stated that schwannomas account for 1 to 10% of all primary retroperitoneal neoplasms, with neurofibromas and

FIG. 5. Cellular (Antoni A) area of tumor contains Verocay body (arrow), comprised of palisaded cell nuclei. H & E, reduced from XlOO.

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malignant schwannomas more commonly arising in the retroperitoneum compared with benign schwannomaso Jow et al reported on the first case of a malignant juxta-adrenal schwannomao1 To our knowledge, we report the first case of a benign juxta-adrenal schwannoma with associated simultaneous multiple posterior mediastinal masses that resemble an adrenal carcinoma with metastasis" Only 4 benign juxta-adrenal schwannomas have been described in the literature"s-s The preoperative diagnosis of a retroperitoneal schwannoma is difficult to establish" Vague, poorly localized back pain is the most common symptom" Other nonspecific findings, such as weight loss, hematuria, anemia, and fever, are associated with malignant schwannomaso Presentation usually occurs later in life, between the third and seventh decades" The sex distribution is equaL 9 Schwannomas that occur at the peripheral nerve regions rarely exceed 6 cmo in diametero 10 Retroperitoneal or mediastinal tumors can attain much larger size" There is no correlation between size and malignant potential or biological aggressivenesso 9 Thus, wide surgical excision is the treatment of choice" Ultrasonography and CT are useful to delineate a solid or cystic mass" Ghiatas and Faleski suggested that CT appearance of masses with calcifications occurred more commonly in neurofibromas than in schwannomaso 11 They also stated that inhomogeneity suggests malignant disease, especially in patients with neurofibromatosiso Takatera et al noted cystic changes in 63% of the benign and 75% of the malignant retroperitoneal schwannomaso 3 These changes may be an important preoperative diagnostic feature because other retroperitoneal tumors do not frequently form cysts" To date findings from CT and ultrasonography are rather nonspecific and make differentiation of schwannomas from other retroperitoneal tumors difficult" The CT appearance of the current case of a predominantly solid, noncalcified, well encapsulated mass more closely typifies the usual radiological appearance of a schwannomao MRI has recently been used for better delineation of the schwannoma from adjacent viscera" 7, 12 In our case we were unable to delin eate the mass from the adrenal gland with either CT or MRL Displacement of the kidney as well as any adrenal mass may be revealed on excretory urographyo Other retroperitoneal schwannomas may create a mass effect with ureteral deviation and hydronephrosis, and may help to exclude the possibility that tumors have originated from these organs" Arteriography has been recommended in view of the rich supply of vessels and nerves to the adrenal gland" However, of 6 instances of retroperitoneal schwannoma reported in the past 3 were hypervascular and 3 were avascularo 13-16 Nonspecific signs of a retroperitoneal mass identified by angiography are stretching or displacement of the arteries and organs that they supply" Angiography can be used to demonstrate the location, blood supply and area invaded the tumor, and to determine if the tumor is resectableo 17 Aspiration needle biopsy has been attempted but because of difficulty in histological interpretation (that is pleomorphism of the cells) this has been discouragedo 18 Guz et al also found CT-guided biopsy to be inaccurate and sometimes misleading, and stated that one should not rely on iL 7 In this case, preoperative radiographic and endocrine evaluations were highly suggestive of a nonfunctioning adrenal tumor with metastasis" Pathologically, schwannomas compress adjacent structures without invasion and rarely, if ever, become malignant" Usually, schwannomas are identified easily by light microscopy but when found at unusual locations, such as the retroperitoneum, they can be confused with other benign or malignant spindle cell neoplasms" Small schwannomas are solid and well encapsulated but when enlarged they may become cystic secondary to hemorrhage or necrosiso 19 Two histological patterns for schwannomas exist: 1) Antoni A with interwoven bundles of bipolar cells in a well organized, often palisading pattern and 2) Antoni B with loose-textured

pleomorphic cells, 19 Some large necrotic schwannomas with a lack of typical Antoni A or B features and pleomorphism of cells may mislead a pathologist into a diagnosis of malignant diseaseo The prognosis of retroperitoneal benign schwannomas is excellent. Although malignant transformation occurs, it is usually associated with von Recklinghausen's diseaseo 20 Therefore, it is suggested that a careful examination for von Recklinghausen's disease be made preoperativelyo We recommend wide surgical resection with adequate margins as described previouslyo 13- 21 Schwannomas contain only Schwann's cells, and nerve fibers course around the tumor, permitting surgical removal and thereby sparing the nerveo 22 Simple enucleation has been performed but several studies have shown recurrent growth, pain, chylous ascites and the potential for malignant transformation of retained tumoro 150 180 23 -27 CONCLUSION

Benign schwannomas are uncommon retroperitoneal tumors" Radiological imaging, such as CT, MRI and ultrasonography, is used to characterize a lesion but these studies are not specific enough to provide a preoperative diagnosis of schwannoma" Similarly, needle biopsy is unreliable" Although multiple lesions often suggest a malignancy with metastasis, surgery may be required to exclude a benign process" To our knowledge we report the first case of a benign juxta-adrenal schwannoma with simultaneous multiple posterior masses masquerading as an adrenal carcinoma with metastasis" We recommend that schwannomas be included in the differential diagnosis of a juxta-adrenal masso REFERENCES

L Jow, Wo, Satchidanand, So, Spinazze, K and Lillie, Do: Malignant juxtadrenal schwannoma" Urology, 38: 383, 199L 20 Steers, WO Do, Hodge, Go R, Johnson, Do K, Chaitin, R A and Charnsangavej, Co: Benign retroperitoneal neurilemoma without von Recklinghausen's disease: a rare occurrence" Jo UroL, 133: 846, 19850 30 Takatera, R, Takiuchi, ff, Namiki, Mo, Takaha, Mo, Ohnishi, So and Sonoda, To: Retroperitoneal schwannomao Urology, 28: 529, 19860 40 Scanlan, Do R: Primary retroperitoneal tumors" Jo UroL, 81: 740, 19590 50 Maeshima, So, Nakamura, Ho, Nishikawa, Mo, Murakami, To, Mitani, To, Marukawa, To, Hori, So, Kozuka, To and Irimoto, Mo: Retroperitoneal schwannomas simulating adrenal tumors" Clin" Imaging, 16: 121, 19920 60 Kihara, Mo, Umemura, So, Takagi, No, Hirawa, No, Minamisawa, K, Matsukawa, To, Miyajima, K, Shionoiri, ff and Ishii, Mo: Neurilemoma of the retroperitoneumo Klino Wochenschro, 69: 228, 199L 7. Guz, R Vo, Wood, Do Po Jr., Montie, Jo K and Pontes, Jo K: Retroperitoneal neural sheath tumors: Cleveland Clinic experience" Jo UroL, 142: 1434, 19890 80 Oliver, WO R, Reddick, R Lo, Gillespie, Goy and Siegal, Go Po: Juxtadrenal schwannoma: verification of the diagnosis by immunohistochemical and ultrastructural studies" Jo Surgo OncoL, 30: 259, 19850 90 Felix, K Lo, Wood, Do K and Das Gupta, To K: Tumors of the retroperitoneum" CurL ProbL Cancer, 6: 1, 198L 100 Stout, Ao Po: The peripheral manifestations of the specific nerve sheath tumor (neurilemoma)o Amero Jo Cancer, 24: 751, 19350 lL Ghiatas, Ao A, and Faleski, K Jo: Benign solitary schwannoma of the retroperitoneum: CT features" South" Medo Jo, 82: 801, 19890 120 Kim, So R, Choi, R L, Han, Mo Co and Kim, Yo L: Retroperitoneal neurilemoma: CT and MR findings" AJR, 159: 1023, 19920 130 Bair, K Do, Woodside, Jo R, Williams, WO L and Borden, To Ao: perirenal malignant schwannoma presenting as renal cell carcinoma" Urology, 11: 510, 19780 140 Miller, Po L, Tessler, k, Alexander, So and Pinck, R Do: Retroperitoneal neurilemmoma" Urology, 11: 619, 19780 150 Herrington, Jo Lo, Jr, and Edwards, L Wo: Massive retroperitoneal neurilemoma, with emphasis on technical problems encountered during surgical removaL Surgery, 57: 366, 19650

416

MULTIPLE RETROPERITONEAL SCHWANNOMAS

16. Kragh, L. V., Soule, E. H. and Masson, J. K.: Benign and malignant

neurilemmomas of the head and neck. Surg., Gynec. & Obstet., 111: 211, 1960. 17. Kuo, C. H., Sheen, I. S. and Wu, C. S.: Retroperitoneal neurilemoma: clinical features in 10 cases. J. Formosan Med. Ass., 89:

22. Whitaker, W. G. and Droulias, C.: Benign encapsulated neurilemoma: a report of 76 cases. Amer. Surg., 42: 675, 1976. 23. Das Gupta, T. K. and Brasfield, R. D.: Solitary malignant schwannoma. Ann. Surg., 171: 419, 1970. 24. Maher, E. and Goodman, M. L.: Retroperitoneal malignant

schwannoma and chylous effusions. Arch. Intern. Med., 118:

704, 1990. 18. Regan, J. F., Jules, G. L. and Schmutzer, K. J.: Retroperitoneal neurilemoma. Amer. J. Surg., 134: 140, 1977. 19. Donna!, J. F., Baker, M. E., Mahony, B. S. and Leight, G. S.: Benign retroperitoneal schwannoma. Urology, 31: 332, 1988. 20. Ball, J. H., Sonnendecker, E. W., Sevitz, H. and Murray, J.:

356, 1965. 26. Carpenter, W. B. and Kernohan, J. W.: Retroperitoneal gangli-

Retroperitoneal malignant schwannoma. A case report. S. Afr. Med. J., 71: 49, 1987. 21. Ghosh, B. C., Ghosh, L., Huvos, A.G. and Fortner, J. G.: Malignant schwannoma: a clinicopathologic study. Cancer, 31: 184, 1973.

oneuromas and neurofibromas. A clinicopathological study. Cancer, 16: 788, 1963. 27. Foote, M. N., Luongo, V. and Marino, E. R.: Benign giant retroperitoneal neurilemoma. Ann. Surg., 157: 719, 1963.

168, 1966. 25. Fein, R. L. and Hamm, F. C.: Malignant schwannoma of the renal

pelvis: a review of the literature and a case report. J. Urol., 94: