Giant intrasacral schwannomas: Report of six cases

Acta Neurochir (Wien) (1997) 139:954-960

Acta Neurochirurgica 9 Springer-Verlag 1997 Printed in Austria

Giant Intrasacral Schwannomas: Report of Six Cases J. Dominguez ~, R. D. Lobato 1, A. Ramos 2, J. J. Rivas ~, P. A. G6mez l, and S. Castro 1 1Department of Neurosurgery and 2Service of Neuroradiology, Hospital "12 de Octubre", Madrid, Spain

Summary

s c h w a n n o m a w h i c h o r i g i n a t e d w i t h i n t h e sacral c a n a l

Only 4 of the 30 previously reported cases of giant sacral schwannomas have been studied with Magnetic Resonance Imaging (MRI). We are reporting 6 more cases, 5 of which had MRI studies. There were 5 women and 1 man (average age 45 years) with long lasting symptoms consisting of lumbosacral and radicular pain accompanied by urinary disturbances and dysaesthetic sensations in the lower limbs. CT clearly defined sacral bone involvement but poorly demonstrated intraspinal tumour extension which was more evident in MRI studies. MRI also clearly showed the intrapelvic extension of the tumour, its relationship with the neighbouring structures and the dumbell growth pattern due to turnout extension through sacral foramina which are important data for making a properative diagnosis and surgical planning. Surgical treatment consisted of piecemeal turnout resection through a posterior approach in four cases. Two patients underwent operation through an abdominal transperitoneal approach followed by a sacral laminectomy. Total intracapsular resection was apparently achieved in 5 cases. Through an average follow-up period of 9.2 years and despite a rather conservative approach, the recurrence rate has been very low in our series and only one patient had to be re-operated on for tumour recurrence.

a n d e x t e n d e d into the r e t r o r e c t a l s p a c e b y e r o d i n g the

Keywords: Cauda equina; magnetic resonance; schwannoma; spinal tumour.

sacrum;

Patients and Methods Five women and one man with giant sacral schwannomas have been surgically treated in our Hospital between July '76 and October '95. The ages of the patients ranged from 17 to 68 years (mean 45 years) (see Table 1). Five patients were symptomatic at the time of presentation and the duration of symptoms ranged from six months to 15 years (average 6.7 years). Four patients complained of pain which was initially localized in the lumbosacral region and extended to the territories of one or more lumbar or sacral roots later in their progress. Three of them also developed urinary hesitancy. One patient who was diagnosed after being admitted for a moderate head injury, had had occasional urinary incontinence without lumbar pain during the past five years. Two patients complained of dysaesthesiae involving the lower extremities. Finally, in one patient the sacral schwannoma was incidentally found during a routine gynaecological examination. Neurological signs present in the 5 patients symptomatic at presentation included lower extremity weakness in 2 cases, decreased deep tendon reflexes in 4, and diminished peri-anal or lower extremity sensation in 4.

Radiologic Diagnosis

Introduction Schwannomas

are b e n i g n t u m o u r s t h a t arise f r o m

the neoplastic transformation

of nerve sheath cells

a n d t h e y are t y p i c a l l y f o u n d a l o n g p e r i p h e r a l n e r v e roots or cranial nerves. S p i n a l s c h w a n n o m a s are r e l a t i v e l y u n c o m m o n a n d less t h a n 1 - 5 % o f all s p i n a l s c h w a n n o m a s the s a c r u m [2]. S c h w a n n o m a s

o c c u r in

also represent a minor

fraction of the different types of tumours arising from the s a c r u m [2, 22]. T h e r e are 30 p r e v i o u s l y r e p o r t e d c a s e s o f s a c r a l schwannomas

a n t e r i o r w a l l o f the s a c r u m .

[ 1 - 4 , 7 - 1 2 , 14, 1 6 - 2 1 ] . W e are r e p o r t -

ing our experience

w i t h six c a s e s o f g i a n t s a c r a l

Plain roentgenograms of the spine revealed extensive lytic sacral lesions with sclerotic borders in five patients. The lesion was limited to the right sacral wing in one case whereas in the remaining patients there was diffuse sacral destruction. Small punctiform calcifications scattered through the lesion were seen in one case. CT, which was performed in four patients, showed both bone involvement and the presacral mass but poorly defined the intraspinal extension of the turnout. Partial sacral destruction with well defined borders was present in all cases. In addition, CT showed involvement of the right sacro-iliac joint in two patients and wide erosion of the $1-$2 foramen in two other cases. MRI was available in five patients. In one case it was performed 17 years after initial surgery when the patient developed massive tumour recurrence. The turnouts appeared iso-intense to hyperintense on T1 weighted sequences and hyperintense on T2 weighted

J. Domfnguez et al.: Giant Intrasacral Schwannomas images except in one case in whom a striking hypo-intense appearance was seen. In the three cases in whom Gadolinium-DTPA was administered there was an intense tumour enhancement that was very helpful in delineating the tumour margins, especially the cephalad intradural extension above the sacrum observed in three of our cases. The average size of the presacral extension was 4.5 cm (range 1-10 cm). Although the intrapelvic structures were displaced anteriorly in two patients, no signs of tumoural invasion were detected in any case. Two patients showed round or oval intratumoural areas which appeared hypo-intense on T1 weighted images and hyperintense on T2 weighted images, probably reflecting cystic degeneration. In one of these cases, punctiform calcifications could also be seen as small foci of hyperintense signals on T1 and hypo-intense on T2. Another important MRI finding was tumour extension through the sacral foramina in all but one of the patients forming a dumb-bell giant shaped mass in three cases.

Surgical Resection In four of our patients surgical treatment consisted of microsurgical piecemeal tumour resection through sacral or lumbosacral laminectomy. In the other two cases, surgery was initially performed by an abdominal transperitoneal approach followed by a sacral laminectomy with intracapsular resection until total removal was achieved according to the surgeon's judgement. No attempt was made to resect the tumour capsule. Three schwannomas extended intradurally requiring open dural procedures and the

955 remainder were entirely extradural. Intra-operative nerve stimulators were not used. Since none of our patients showed signs of lumbosacral or sacro-iliac instability we did not perform fusion procedures in any case. One of the two patients (Case 2) who had been operated on by a combined posterior and anterior approach developed a massive tumour recurrence seventeen years after initial surgery; this 76 year old women was re-operated on through a posterior approach but the turnout could only be partially debulked because of profuse bleeding and secondary haemodynamic instability.

Pathological Diagnosis The histological studies showed the typical findings of schwannoma in 4 cases i.e., a tumour with densely cellular Antoni A areas with well developed nuclear palisading alternating with Antoni B areas containing thick-walled blood vessels, abundant microcyst formation, clusters of haemosiderin laden macrophages and variable amounts of collagen tissue. One tumour (Case 6) showed the characteristic features of a degenerated neurilemmoma or ancient schwannoma and another tumour (Case 5), showing significant hypercellutarity, was included in the group of cellular schwannomas.

Results None of our patients showed neurological worsening after surgery and those complaining hesitancy-incontinence

improved

of urinary

following

opera-

Fig. 1. T1 weighted sagittal image (a) demonstrates a giant sacral schwannoma with extensive intrapelvic component. The uterus (U) and bladder (B) are displaced anteriorly but not invaded. Hypo-intense areas within the tumour (arrows) represent areas of cystic degeneration. Postcontrast sagittal image (b) shows intense tumour enhancement excepting for the degenerative cystic areas

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J. Domfnguez et al.: Giant Intrasacral Schwannomas

Fig. 2. Coronal T 1 (a) and T2 (b) weighted images show a schwannoma iso-intense on T 1 and hyperintense on T2 that produces a clear erosion of the left S1 and $2 neural foramina

Fig. 3. T1 weighted sagittal images before (a, left) and after (a, right) intravenous contrast injection show a well delineated schwannoma. The tumour erodes the L5 endplate and destroyes the two first sacral vertebral bodies. The intradural sacral extension of the tumour is better appreciated on the postcontrast image. Axial CT scan (b) demonstrates diffuse sacral destruction with extension into the right sacro-iliac joint. There are small foci of calcification or residual bone within the mass

tion. A t s u b s e q u e n t clinical e v a l u a t i o n the patients r e m a i n e d a s y m p t o m a t i c except for the w o m a n with late t u m o u r r e c u r r e n c e who suffered l u m b o s a c r a l p a i n and u r i n a r y hesitancy. All patients have had postoper-

ative M R I controls. I n one p a t i e n t with a s s u m e d total t u m o u r resection, the early postoperative M R I s h o w e d a small residual tumour. This patient has r e m a i n e d a s y m p t o m a t i c for the n e x t four years with-

J. Domfnguez et

al.:

Giant Intrasacral Schwannomas

957

Fig. 4. Lumbosacral radiograph (a) shows a sacral lyric lesion limited to the right sacral wing. On the axial CT scan (b) there is a a polylobulated lytic lesion at S 1 level with clear involvement of the right sacro-iliac joint and presacral extension (arrows). The axial T 1 weighted MRI at an inferior level (c), shows the tumour dumbbell appearance with a huge presacral component that extends through the right sacral foramina. The bladder (B) and the rectum (R) are displaced anteriorly but not infiltrated by the tumour

out showing any change in tumour size on subsequent MRI controls. The follow-up period is shown in Table 1.

Discussion Of the malignant tumours originating in the sacrum, chordoma, chondrosarcoma and metastasic lesions are the most common. Benign sacral lesions include giant cell tumour, osteoblastoma and aneurysreal bone cyst whereas schwannomas are very rare at this site [6, 22]. Though the female/male ratio was 5/1 in our series, there was no sex predilection in the 30 cases published up to now [1-4, 7-12, 14, 16-21]. Lumbosacral pain with or without accompanying dysaesthesia was the most prevalent s y m p t o m both in our patients and in the cases previously reported.

Decreased deep tendon reflexes and diminished lower extremity sensation are among the most frequent neurological signs found in these patients. Because of the large capacity for regional expansion of the intrasacral space and the slow growth rate of the tumour, symptoms develop late in the course of the disease when the tumour has reached a large volume in contrast to schwannomas localized in the more proximal segments of the spine which cause compression of the spinal cord leading to an earlier diagnosis [14, 21]. MRI has supplanted previous radiological studies. Though it is inferior to the CT scan for evaluating the degree of bone destruction, it provides a better topographic display of the presacral mass because of its direct multiplanar imaging capacity. In five of our

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J. Domfnguezet al.: Giant Intrasacral Schwannomas

Table 1. Clinical Summary of the Six Cases Reported Age/Sex

Symptoms

Surgical approach

Pathology

Follow up

Case 1

38 F

Lumbar pain,dysaesthesiae urinary hesitancy

Posterior 1976

Benign Schwannoma

Asymptomatic, no recurrence on MRI

Case 2

59 F

Lumbar pain, urinary hesitancy

Posterior, anterior1 9 7 6 , Posterior 1993

Benign Schwannoma

Recurrence 1993

Case 3

68 F

Lumbar pain, urinary hesitancy

Posterior 1991

Benign Schwannoma

Case 4

23 M

Urinary incontinence

Posterior 1993

Benign Schwannoma

Case 5

17 F

Asymptomatic

Anterior, Posterior 1 9 9 5

Cellular Schwannoma

Case 6

39 F

Lumbar pain, dysaesthesiae

Posterior 1995

Ancient Schwannoma

Asymptomatic, no recurrence on MRI Asymptomatic, small residual tumour on MRI Asymptomatic, no recurrence on MRI Asymptomatic, no recurrence on MRI

cases it clearly demonstrated the intraspinal and intrapelvic extension of the tumour as well as the relationship with neighbouring structures. It also recognized the dumb-bell growth pattern due to the extension of the tumour through the sacral foramina which is very useful for an appropriate pre-operative diagnosis and surgical planning in these patients. The choice of the surgical approach in patients with a suspected sacral schwannoma is dependent upon the degree of both sacral destruction and intrapelvic extension which are in direct relationship with tumour size. Most authors have recommended an aggressive approach with the aim of achieving a complete resection even if it results in the loss of bowel or bladder control [2, 18]. Though we used a conservative approach, the recurrence rate in our series was 16% with a follow-up period ranging from 18 months to almost 21 years (average 9.2 years). Abernathy et al. [2] reported a recurrence rate of 54% after a conservative approach (intracapsular enucleation) in their patients who were followed for periods ranging from 5 months to 33 years (mean 9 years). A combined abdominosacral approach allows an easier resection of the intrapelvic tumour components and carries low risk of injury to the pelvic vasculature, whereas the posterior approach allows a better exposure of the nerve roots and the canda equina [13, 21]. Though we do not have experience with the corn-

bined abdominosacral approach we believe that by using current neuro-imaging techniques the patient can be followed accurately thus avoiding aggressive surgical manoeuvres at initial operation which can seriously affect the quality of life for the patient. For the rare patient with high anaesthetic or surgical risk, as in one of ours who developed profuse intra-operative bleeding, radiation therapy may be considered. Of the two patients previously reported who were treated by radiotherapy one showed tumour growth arrest for five years [ 11 ] and the other did not respond at all [9]. Histopathologically, neither our patients nor other previously treated cases showed signs of malignancy [1-4, 7-12, 14, 16-21]. One of the tumours in our series was an ancient schwannoma which is an unusual pathological variant with a high propensity to haemorrhage, calcification and formation of degenerative cysts; this tumour also contains cells with large atypical nuclei that may suggest a malignant diagnosis, in spite of the fact that mitosis are usually absent [5, 15]. Another tumour showed a significant increased cellularity and was classified with the group of cellular schwannomas of Woodruff et al. [23]. Another four cases of giant sacral cellular schwannomas have been reported and while the three cases in the series of Abernathey et al. [2], did not show a more aggres-

959

J. Domfnguez et al.: Giant Intrasacral Schwannomas sive b e h a v i o u r than c o n v e n t i o n a l s c h w a n n o m a , the cellular s c h w a n n o m a reported by F e l d e n z e r et al. [9] showed a rapid growth c a u s i n g the p a t i e n t ' s death one year after diagnosis despite additional radiotherapy and chemotherapy. T h o u g h the follow up in our cases is still very short the clinical b e h a v i o u r has b e e n also benign.

Conclusions T h o u g h both the n u m b e r of patients and the length of the f o l l o w - u p are relatively short in our series we can draw the f o l l o w i n g c o n c l u s i o n s : 1) The d u r a t i o n of s y m p t o m s in patients with giant sacral s c h w a n n o mas is e x t r e m e l y long (average 6.7 years) p r o b a b l y due to the large capacity for r e g i o n a l e x p a n s i o n of the intrasacral space and the slow growth rate of the tumour. 2) M R I is a most useful diagnostic tool. In the five cases in w h o m it was p e r f o r m e d it clearly showed the intrapelvic and intraspinal e x t e n s i o n of the t u m o u r as well as its r e l a t i o n s h i p to the n e i g h b o u r i n g structures; it also r e c o g n i z e d a d u m b - b e l l growth pattern due to e x t e n s i o n of the t u m o u r through the sacral f o r a m i n a that is useful for an appropriate pre-operative diagnosis and surgical p l a n n i n g . 3) T h o u g h we used a rather c o n s e r v a t i v e approach, n o n e of our patients showed n e u r o l o g i c a l w o r s e n i n g after surgery and the r e c u r r e n c e rate has b e e n very low.

References I. Abdelwahab IF, Hermann G, Stollman A, Wolfe D, Lewis M, Zawin J (1989) Case report 564: giant intraosseous schwannoma. Skeletal Radiol 18:466-469 2. Abernathey CD, Onofrio BM, Scheithauer B, Pairolero PC, Shives TC (1986) Surgical management of giant sacral schwannomas. J Neurosurg 65:286-295 3. Anson KM, Byrne PO, Robertson ID, Gullan RW, Montgomery ACV (1994) Radical excision of sacrococcygeal tumours. Br J Surg 81:460-461 4. Conley AH, Miller DS (1942) Neurilemmoma of bone: a case report. J Bone Joint Surg (Am) 24:684-689 5. Dahl I (1977) Ancient neurilemmoma (Schwannoma). Acta Pathol Microbiol Scand Sect (A) 85:812-818 6. Dahlin DC, Unnik KK (1986) Bone tumors: general aspects and data on 8542 cases, 4th ed. Thomas, Springfield, pp 12-13 7. De la Monte SM, Dorfman HD, Chandra R, Malawer M (1984) Intraosseous schwannoma: Histologic features, ultrastructure and review of the literature. Hum Pathol 15:555-558 8. DeSanto DA, Burgess E (1940) Primary and secondary neurilemmoma of bone. Surg Gynecol Obstet 71:454-461 9. Feldenzer JA, McGautey JL, McGillicuddy JE (1989) Sacral and presacral tumors: Problems in diagnosis and management. Neurosurgery 25:884-891

10. Jaffe HL (1958) Tumors and tumorous conditions of bone and joints. Lea and Febiger, Philadelphia, pp 126-131 11. Kotoura Y, Shikata J, Yamamuro T, Kasahara K, Iwasaki R, Nakashima Y, Yamabe H (1991) Radiation therapy for giant intrasacral schwannoma. Spine 16:239-242 12. Lesoin F, Krivosic I, Cama A, Jomin M (1984) A giant intrasacral schwannoma revealed by lumbosacral pain. Neurochirurgia (Stuttg) 27:23-24 13. Localio SA, Eng K, Ranson JH (1980) Abdominosacral approach for retrorectal tumors. Ann Surg 191: 555-560 14. Rengachary S, O'Boynick P, Batnitzky S, Kepes JJ (1981) Giant intrasacral schwannoma: Case report. Neurosurgery 9: 573-577 15. Russell DS, Rubinstein LJ (1989) Pathology of tumors of the nervous system 5th ed. Williams and Wilkins, London, pp 533-589 16. Samter TG, Vellois F, Shafer WG (1960) Neurilemmoma of bone: report of three cases with a review of the literature. Radiology 75:215-222 17. Salvant JB, Young HF (1994) Giant intrasacral schwannoma: An unusual cause of lumbosacral radiculopathy. Surg Neurol 41:411-413 18. Santi MD, Mitsunaga MM, Lockett JL (1993) Total sacrectomy for a giant sacral schwannoma. A case report. Clin Orthop 294:285-289 19. Stecken J, Bardaxoglou E, Touquet S, Manzo N, Cherki E, Dorwling-Carter D, Muckensturm B (1996) Schwannome sacr6 g6ant avec extension pelvienne. Strattdgie thdrapeutique. propos d'un cas. Neurochirurgie 42:294-299 20. Stewart RJ, Humphreys WG, Parks TG (1986) The presentation and management of presacral tumours. Br J Surg 73: 153-155 21. Turk PS, Peters N, Libbey Wanebo HJ (1992) Diagnosis and management of giant intrasacral schwannoma. Cancer 70: 2650-2657 22. Turner ML, Mulhern CB, Dalinka MK (1981) Lesions of the sacrum. Differential diagnosis and radiological evaluation. JAMA 245:275-277 23. Woodruff JM, Susin M, Godwin TA, Martini N, Erlandson RA (1981) Cellular schwannoma. A variety of schwannoma sometimes mistaken for a malignant tumor. Am J Surg Pathol 5: 733-744

Comments This is a very straightforward report of a rare cIinical entity. The various aspects, including clinical and radiological diagnosis and treatment are clearly described. The advice for a rather conservative surgical approach, consisting of intracapsular removal, seems wise in view of the benign course of the disease. Personally I have experienced a patient with a sacral schwannoma who showed malignant degeneration in the course of the disease. After treatment with radiotherapy and chemotherapy the condition stabilized for many years. This article reminds me of the lesson I learned from one of my old teachers that on plain X-ray films of the lumbar, sacral vertebral column, abnormalities of the sacrum are often overlooked. C. Avezaat

The neurosurgical group from Madrid presents here six patients, operated on for giant size intrasacral schwannomas. The

960 first two patients were operated on 1976, one re-operated 1993, all the others have been treated in the 90's. Median follow-up is 3 years, mean follow-up 9.2 years and presented in the summary, what is not suitable for such extremely varying follow-ups. The syndrome is not very common, and may he underdiagnosed. I think that the authors are giving an important message, the tumour behaves in a benign way and it can be treated by conservative intracapsular surgery either posteriorly or by a combined anterior and posterior approach. All the patients were adults by the time of the operation, mostly symptomatic with duration between 6 month and 15 years. Lower extremity pain and dysaesthesia were the major symptoms, together with urinary difficulties. Diagnosis and operative planning were based on MRI, but CT also gave important information. All the cases are presented in one informative table, with the outcome

J. Domfnguez et al.: Giant Intrasacral Schwannomas of the patient. There are 9 pictures of 4 patients, all very informative. The most important differential diagnostic lesions of sacrum are presented in the discussion part of the paper with good coverage of this subject. Conclusions are careful. Is there any connection of this syndrome to NF 1? M. Vapalahti Answer from the authors: None of our cases showed NF1 criteria. Correspondence: Jaime Domfnguez, M. D., Servicio de Neurocirugfa, Hospital "12 de Octubre", Ctra de Andalucfa Km 5.4, Madrid 28041, Spain.