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Giant lumbosacral nerve sheath tumors
118
Surg Neurol 1992;37:118-22
Giant Lumbosacral Nerve Sheath Tumors Sanjiv Bhatia, M.Ch., Anil Khosla, M.D., Rajiv Dhir, M.D., Ravi Bhatia, M.Ch., and Ajit K. Banerji, M.S. Departments of Neurosurgery, Neuroradiology, and Pathology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
Bhatia S, Khosla A, Dhir R, Bhatia R, Banerji AK. Giant lumbosacral sheath tumors. Surg Neurol 1992;37:118-22.
Cauda equina nerve sheath tumors are usually small, wellencapsulated tumors. Sometimes they may attain very large proportions, cause extensive bony changes, and resemble ependymomas in the cauda equina. They may also infltrate into adjacent soft tissue planes and retroperitoneal spaces and yet be histologically benign. An awareness of this entity ensures aggressive surgical removal at the time of exploration. Primary neurofibrosarcomas or malignant changes in primary nerve sheath tumors of the cauda equina are seen in patients with neurofibromatosis. KEY WORDS: Large nerve sheath tumors; Cauda equina; Differential diagnosis
Neurofibromas account for about one fourth of all spinal neoplasms [3,12,18]. These tumors are most often solitary and, when multiple, are indicative of von Recklinghausen disease. The majority of these tumors are located in the thoracic region and the rest are evenly distributed in the cervical and lumbar regions. Tumors localized to the sacral region comprise 1%-57/c of all spinal neurofibromas [3,16]. Ependymomas and neurofibromas are the two most common tumors in this region. Ependymomas are known to attain large size, but this is u n c o m m o n for neurofibromas. Most nerve sheath tumors are small, solitary, and benign [ 19]. Large tumors are encountered uncommonly and when seen in the lumbosacral region present problems of diagnosis and treatment quite different from problems posed by nerve sheath tumors elsewhere. These tumors may lack a well-defined capsule in some areas and may extend into the retroperitoneal, presacral, and soft tissue planes without having under-
Addre.~s reprint requests to." Professor Ajit K. ganerji, Head, Department of Neumsurgery, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India. Received May 7, 199l; accepted _July 2~, 1991.
't 1992 by Elsevier Science PublishingCo., Inc.
gone view such with
a malignant change histologically [ 1,15,17]. A reof the literature reveals isolated case reports of large tumors. This article presents our experience ten patients with giant nerve sheath tumors.
Case M a t e r i a l Ten patients with giant intraspinal lumbosacral nerve sheath tumors were operated on from January 1972 through O c t o b e r 1989. T h e r e were five men and five w o m e n whose ages ranged from 17 to 55 years, for an average age of 42 years. These patients presented with a varied combination of pain, motor deficit, sensory impairment, and autonomic dysfunction with the duration of symptoms ranging from 1.5 to 9 years (average duration of 4 years). Pain was the most frequent symptom. Localized low backache with or without radiculopathy was the initial or subsequent symptom in nine patients. It was aggravated by exertion, straining, and recumbency; when severe, it prevented a supine posture and often disturbed sleep. Pain was worse on recumbency in three patients. One patient with a predominant sacral and presacral tumor did not have any pain. All patients had m o t o r weakness and eight had hypoesthesia. Three patients had perianal hypoesthesia. H y poreflexia or areflexia was present in all the patients. Autonomic disturbances were seen in seven patients, of whom five had frequency and dribbling of urine, two had severe constipation, and two had impotence. Two patients developed renal dysfunction secondary to neurogenic bladder. Intraabdominal or pelvic retroperitoneal extension of the tumor was seen in three patients, but none of these patients had any evidence of renal dysfunction. Local tenderness was seen in five patients, but a large local swelling secondary to tumor spread to the muscle planes was seen in only one patient. One patient had bilateral pes cavus. Generalized neurofibromatosis was seen in one patient. One patient required reoperation 14 months later, and another 4 years later, 0090-3019/92/S5.00
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119
the latter for a recurrence of t u m o r and the former for residual tumor.
Radiological Findings The plain radiographs suggested an expansile intraspinal large mass at multiple vertebral body levels. The various radiological findings suggestive of intraspinal mass were increased interpedicular distance with deformed pedicles, posterior scalloping of the vertebral bodies, and erosion of the vertebral bodies and appendages (Figure 1 A and B). Two patients had hydroureteronephrosis secondary to neurogenic bladder, as revealed by intravenous pyelography and ultrasonography. Myelography performed in eight patients through the cervical or cisternal route showed a complete block at the upper level of the lesion in all patients. C o m p u t e d tomography was performed for two patients to evaluate the intrasacral, presacral, and retroperitoneal extension of the tumor.
Operative
Findings
All patients were operated on in the prone position. One patient was operated on for the retroperitoneal pelvic mass prior to surgery for the spinal tumor. The laminae were markedly thin in the majority of patients and the dura was thin and attenuated. The margins of the tumor were ill defined in all the patients, and the capsule could not be clearly identified. The consistency was variable. The tumor was yellowish and resembled a myxopapillary e p e n d y m o m a of the cauda equina. The roots of the cauda equina were engulfed in the tumor, and in no patient could an attachment to a nerve root indicating the site of origin be identified. Despite the use of the operating microscope, one could not be certain about the completeness of the surgical excision. An ultrasonic surgical aspirator was used in two cases; this facilitated the removal of the tumor between the roots and helped in their preservation. Anterior extension of the tumor could be seen in three patients, thus confirming that the retroperitoneal tumor was in reality an extension of the spinal tumor and not a separate entity. In all patients an attempt was made to do as radical a removal as possible. Dural closure was invariably difficult and incomplete. Dacron duraplasty was carried out in one patient. Reoperation was done in two patients.
Pathological F i n d i n g s There were ten cases, of which nine were benign nerve sheath tumors and one was a neurofibrosarcoma at the time of initial surgical resection. The morphology of a majority o f the benign nerve
Figure 1. Radiograph .,howing enlargement o/-the /umbo~aera/ eanalfrom an intrasacra/ mas~ that has resulted in erosion o/the posterior surfaee of the boff~, ~/ the ~fth lumbar anal jacra/ tertebrae.
sheath tumors was that of a schwannoma (seven of nine cases), and the remaining two cases showed features of a neurofibroma. One case, a schwannoma, recurred 4 years later and showed malignant transfi)rmation into a neurofibrosarcoma.
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Bhatia et al
Figure 2. Benign nerve sheath tumor u,ith prominent Verocay bodies (magnification × 367~.
The schwannomas showed distinct Antoni type A and type B areas. The type A areas were moderately cellular, with spindle-shaped cells arranged in a pallisading or organoid pattern. Formation of occasional Verocay bodies was noted (Figure 2). There was no mitosis. The type B areas showed polyhedral cells with vacuolated cytoplasm. Focal lymphocytic infilteration was also seen (Figure 3). Hyaline thickening of the blood vessels was frequently seen. The neurofibromas had sparse cellular components with abundant collagen fibers. The tumor cells had elongated nuclei with a wavy serpentine configuration and were pointed at both ends. The nerve sheath tumors were considered to be malignant when evidence of mitosis with or without necrosis was seen in the tissues. The neurofibrosarcomas had features of a nerve sheath origin. In addition the mitotic rate was increased, being 7 - 8 per 10 hpf in one case and 2 - 3 per 10 hpf in the other.
Results At the time of discharge five patients had improved and four were unchanged. Pain was relieved in all five patients and there was i m p r o v e m e n t in their walking. The sensory and m o t o r functions had improved to a variable degree. One patient who had required Dacron duraplasty developed meningitis secondary to a dural fistula from the wound and died. Seven patients returned for follow-up. Two of the four patients who had been unchanged at the time of discharge were lost to follow-up. The maximum follow-
up ranged from 4 months to 4 years in the remaining patients. Four patients showed remarkable improvement in their sensorimotor deficit and were left with only minimal residual disability. One patient with a predominant sacral and presacral tumor with predominant urinary disturbances did not show any significant improvement. Two patients were again operated on, at 4 years and at 15 months after the first operation. The former had recurrence of symptoms and a malignant transformation to a neurofibrosarcoma was histologically confirmed.
Discussion N e r v e sheath tumors of a large size are seen most often in the peripheral form of neurofibromatosis, as in plexiform neurofibromas or neurofibrosarcomas. H o w e v e r , intraspinal plexiform neurofibroma is a rare entity [20]. Large nerve sheath tumors in the spinal axis are uncommon [1,15,17]. A large series of studies of spinal neurofibromas does not mention this entity [3,9,10,16,22]. Although usually benign, they may sometimes be malignant or undergo a malignant transformation, especially in patients with neurofibromatosis [5,19]. Pain is a predominant feature in patients with cauda equina tumors of all sizes [1,9,10,17]. It is often worse on recumbency [ 14], with patients waking in the middle of the night with excruciating pain. The pain has a progressive course, unlike that of some patients with disk disease who have frequent remissions and relapses [9]. Benign tumors of the spinal column such as osteoid osteoma may also cause severe pain especially at night.
Giant Nerve Sheath Tumors
Surg Neurol 1992;37:118-22
121
Figure 3. Benign nerve sheath tumor with Antoni type B areas, showing cells with t,acuolated cytoplasm and areas of mild lymphocytic infiltration (magnification × 459).
These are characteristically relieved with aspirin [11]. Painless cauda equina tumors are extremely rare [4]. Only one of our patients had no pain. Abernathey et al [1], in their series of 13 cases of giant sacral schwannomas, described pain as the most important symptom. Gautier-Smith [ 10] reported pain in 33 of a series of 34 patients with lumbar neurofibromas. Rao [ 16] described clinical features of 23 patients with lumbar neurofibromas, 75% of whom had radiculopathy and almost all of whom had signs of m o t o r or sensory involvement. Only three patients in the series by Abernathey et al [1] had lower extremity sensorimotor defcit on examination. All the patients in the present series had sensorimotor deficit of variable severity. Autonomic disturbances are seen in 2 0 % - 5 0 ~ of patients [10,16]; they were present in six of our patients. While trauma and degenerative disease of the spine are the major causes of backache and radicular pain in the legs, occasionally patients with small intradural neurofibromas may present in a similar condition [21,23]. These patients do not show any changes on ~lain radiographs. The diagnosis is suggested by the aggravation of pain on recumbency and an elevated spinal fluid protein concentration. Focal bony changes, revealed in radiographs, suggest a spinal tumor has been seen in 4 0 ~ - 4 9 ~ of patients [6,13,16]. Focal erosion ofpedicles, enlarged intervertebral foramina, posterior scalloping, and widened interpedicular distance are some of the changes that have been observed. These changes were all localized and the tumors in all these cases were small. In the present series extensive bony changes were seen. T h e r e was widening of the interpedicular distances and scalloping of three or
four adjacent lumbar vertebrae, as well as thinning of the laminae. Extensive destruction of the anterior lumbosacral vertebra with intrapelvic extension of neurofibromas has been described [1,15,17]; this was also seen in two of our patients. Though usually benign histologically, these tumors may attain large proportions; they may even extend through the dura into the extradural tissues posteriorly and erode into the vertebral body and extend into the retroperitoneal space anteriorly, thereby presenting as an abdominal or pelvic mass. The gross appearance of these tumors at operation, the obvious infiltration into the dura and surrounding soft tissue, their extreme vascularity, and the fact that the nerve roots are intimately enmeshed in the tumor with no apparent attachment to any nerve root, all suggest the diagnosis of a malignant tumor of the cauda equina. Retroperitoneal or intrapelvic masses were seen in three patients. Only one of these had neurofibromatosis. Although these tumors are large and extensive and tend to transgress tissue planes, they are most often histologically benign, as was seen in all but one of our patients. One of the tumors underwent a malignant change and later recurred. Primary neurofibrosarcomas are often seen in patients with neurofibromatosis [ 19]. These are younger patients. Only one of our patients had a primary neurofibrosarcoma and this patient also had neurofibromatosis. Sacral neurofibrosarcomas are rare lesions in the absence of neurofibromatosis. Crosbie et al [5] have reported a case of sacral neurofibrosarcoma that was extending into the presacral region. On the basis of the bony changes alone it is usually
122
Surg Neurol 1992;37:118-22
not possible to differentiate a large benign neurofibroma from a neurofibrosarcoma. Besides large nerve sheath tumors and ependymomas, developmental tumors and metastatic deposits may present in a similar manner [9]. These patients may c o m e to the clinical attention o f a general surgeon, a gynecologist, an orthopedic surgeon, or a nephrologist. It is important to recognize that pain, weakness, and wasting o f the legs, as well as impotence and numbness in the perianal region, may herald an intraspinal cauda equina tumor [7].
Bhatia et al
10. Gautier-Smith PC. Clinical aspects of spinal neurofibromas. Brain 1967;90:359-94. I I. Keim HA. Low back pain. Ciba Clin Symp 1973: p 9. 12. Kernohan JW, Sayre GP. Tumors of the central nervous system (Atlas of Tumor Pathology, section 10, fascicles 35 and 37). Washington DC. Armed Forces Institute of Pathology, 1952: p 141. 13. Levy WJ, Latchaw J, Hahn JF, Sawhney B, Bay J, Dohn DF. Spinal neurofibromas: a report of 66 cases and a comparison with meningiomas. Neurosurgery 1986;18:331-4. 14. Milnes JN. The early diagnosis of tumors of the cauda equina. J Neurol Neurosurg Psychiatry 1953;16:158-65. 15. Osborn RE, DeWitt JD. Giant cauda equina schwannoma: CT appearance. Am J Neurosci Res 1985;6:835-6.
References 1. Abernathey CD, Onofrio BM, Scheithauer B, Pairolero PC, Shives TC. Surgical management of giant sacraJ schwannomas. J Neurosurg 1986;65:286-95. 2. Alien [M. Tumors involving the cauda equina: a review of their clinical features and differential diagnosis. J Neurol Psychopathol 1930;11:111-43. 3. Banerji AK. Epidemiology of CNS tumors 1974-1978. In: Proceedings of the National Seminar on Neurooncology. 1979:43-8. 4. Campbell FG. Painless tumors of the cauda equina: a case report. Neurology (NY) 1963;13:341-43. 5. Crosbie DC, Carney PG, Sage MR. Sacral neurofibrusarcoma--a case report. Australas Radiol 1986;30:54-6. 6. Danziger J. Schwannoma of the CNS. Am J Roentgenol 1975;125:692-701. 7. Editorial: Cauda equina tumors. Br Med J 1978;1(6116):808. 8. Falconer M. Cauda equina tumors. Trans Med Soc Lond 1966;82:126-38. 9. Fearnside MR, Adams CBT. Tumors of the cauda equina.J Neurol Neurosurg Psychiatry 1978;41:24-31.
16. Rao SB. Spinal neurinomas (a study of 80 operated cases). Neurol lndia 1975;23:1-12. 17. Rengachary SS, O'Boynick P, Bamitzky S, KepesJJ. Giant intrasaoral schwannoma: a case report. Neurosurgery 1981 ;9:573-7. 18. Rubenstein L. Tumors of the central nervous system (Atlas of Tumor Pathology, 2nd series, fascicle 6). Washington DC: Armed Forces Institute of Pathology, 1972:169-90. 19. Russell and Rubenstein L. Tumors of cranial, spinal and peripheral nerve sheaths. In: Pathology of the nervous system. Edward Arnold, 1989;533-77. 20. Schumacher M, Gilsbach J, Freidrich H, Mennel HD. Plexiform neurofibroma (Rankenneurofibrom) of cauda equina. Neuroradiology 1978;15:221-4. 21. Tandon PN, Bhargava S, Prakash B, Bhatia R. Lumbar disc prolapse. JAIIMS 1977;2:303-10. 22. Tonnis W, Krenkel, Nitmer K. Ein als Bandscheibenvorfalimpnierendes Kauda--Neurinom. Zentralbl Chir 1963;88: 1293-7. 23. Wiesel SW, Ignatius P, MarvelJP, Rothman RH. Intradural neurofibroma simulating lumbar disc disease. J Bone Joint Surg 1976;58A: 1040-2.
Surg Neurol 1992;37:118-22
Giant Lumbosacral Nerve Sheath Tumors Sanjiv Bhatia, M.Ch., Anil Khosla, M.D., Rajiv Dhir, M.D., Ravi Bhatia, M.Ch., and Ajit K. Banerji, M.S. Departments of Neurosurgery, Neuroradiology, and Pathology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
Bhatia S, Khosla A, Dhir R, Bhatia R, Banerji AK. Giant lumbosacral sheath tumors. Surg Neurol 1992;37:118-22.
Cauda equina nerve sheath tumors are usually small, wellencapsulated tumors. Sometimes they may attain very large proportions, cause extensive bony changes, and resemble ependymomas in the cauda equina. They may also infltrate into adjacent soft tissue planes and retroperitoneal spaces and yet be histologically benign. An awareness of this entity ensures aggressive surgical removal at the time of exploration. Primary neurofibrosarcomas or malignant changes in primary nerve sheath tumors of the cauda equina are seen in patients with neurofibromatosis. KEY WORDS: Large nerve sheath tumors; Cauda equina; Differential diagnosis
Neurofibromas account for about one fourth of all spinal neoplasms [3,12,18]. These tumors are most often solitary and, when multiple, are indicative of von Recklinghausen disease. The majority of these tumors are located in the thoracic region and the rest are evenly distributed in the cervical and lumbar regions. Tumors localized to the sacral region comprise 1%-57/c of all spinal neurofibromas [3,16]. Ependymomas and neurofibromas are the two most common tumors in this region. Ependymomas are known to attain large size, but this is u n c o m m o n for neurofibromas. Most nerve sheath tumors are small, solitary, and benign [ 19]. Large tumors are encountered uncommonly and when seen in the lumbosacral region present problems of diagnosis and treatment quite different from problems posed by nerve sheath tumors elsewhere. These tumors may lack a well-defined capsule in some areas and may extend into the retroperitoneal, presacral, and soft tissue planes without having under-
Addre.~s reprint requests to." Professor Ajit K. ganerji, Head, Department of Neumsurgery, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India. Received May 7, 199l; accepted _July 2~, 1991.
't 1992 by Elsevier Science PublishingCo., Inc.
gone view such with
a malignant change histologically [ 1,15,17]. A reof the literature reveals isolated case reports of large tumors. This article presents our experience ten patients with giant nerve sheath tumors.
Case M a t e r i a l Ten patients with giant intraspinal lumbosacral nerve sheath tumors were operated on from January 1972 through O c t o b e r 1989. T h e r e were five men and five w o m e n whose ages ranged from 17 to 55 years, for an average age of 42 years. These patients presented with a varied combination of pain, motor deficit, sensory impairment, and autonomic dysfunction with the duration of symptoms ranging from 1.5 to 9 years (average duration of 4 years). Pain was the most frequent symptom. Localized low backache with or without radiculopathy was the initial or subsequent symptom in nine patients. It was aggravated by exertion, straining, and recumbency; when severe, it prevented a supine posture and often disturbed sleep. Pain was worse on recumbency in three patients. One patient with a predominant sacral and presacral tumor did not have any pain. All patients had m o t o r weakness and eight had hypoesthesia. Three patients had perianal hypoesthesia. H y poreflexia or areflexia was present in all the patients. Autonomic disturbances were seen in seven patients, of whom five had frequency and dribbling of urine, two had severe constipation, and two had impotence. Two patients developed renal dysfunction secondary to neurogenic bladder. Intraabdominal or pelvic retroperitoneal extension of the tumor was seen in three patients, but none of these patients had any evidence of renal dysfunction. Local tenderness was seen in five patients, but a large local swelling secondary to tumor spread to the muscle planes was seen in only one patient. One patient had bilateral pes cavus. Generalized neurofibromatosis was seen in one patient. One patient required reoperation 14 months later, and another 4 years later, 0090-3019/92/S5.00
Giant Nerve Sheath Tumors
Surg Neurol 1992;37:118-22
119
the latter for a recurrence of t u m o r and the former for residual tumor.
Radiological Findings The plain radiographs suggested an expansile intraspinal large mass at multiple vertebral body levels. The various radiological findings suggestive of intraspinal mass were increased interpedicular distance with deformed pedicles, posterior scalloping of the vertebral bodies, and erosion of the vertebral bodies and appendages (Figure 1 A and B). Two patients had hydroureteronephrosis secondary to neurogenic bladder, as revealed by intravenous pyelography and ultrasonography. Myelography performed in eight patients through the cervical or cisternal route showed a complete block at the upper level of the lesion in all patients. C o m p u t e d tomography was performed for two patients to evaluate the intrasacral, presacral, and retroperitoneal extension of the tumor.
Operative
Findings
All patients were operated on in the prone position. One patient was operated on for the retroperitoneal pelvic mass prior to surgery for the spinal tumor. The laminae were markedly thin in the majority of patients and the dura was thin and attenuated. The margins of the tumor were ill defined in all the patients, and the capsule could not be clearly identified. The consistency was variable. The tumor was yellowish and resembled a myxopapillary e p e n d y m o m a of the cauda equina. The roots of the cauda equina were engulfed in the tumor, and in no patient could an attachment to a nerve root indicating the site of origin be identified. Despite the use of the operating microscope, one could not be certain about the completeness of the surgical excision. An ultrasonic surgical aspirator was used in two cases; this facilitated the removal of the tumor between the roots and helped in their preservation. Anterior extension of the tumor could be seen in three patients, thus confirming that the retroperitoneal tumor was in reality an extension of the spinal tumor and not a separate entity. In all patients an attempt was made to do as radical a removal as possible. Dural closure was invariably difficult and incomplete. Dacron duraplasty was carried out in one patient. Reoperation was done in two patients.
Pathological F i n d i n g s There were ten cases, of which nine were benign nerve sheath tumors and one was a neurofibrosarcoma at the time of initial surgical resection. The morphology of a majority o f the benign nerve
Figure 1. Radiograph .,howing enlargement o/-the /umbo~aera/ eanalfrom an intrasacra/ mas~ that has resulted in erosion o/the posterior surfaee of the boff~, ~/ the ~fth lumbar anal jacra/ tertebrae.
sheath tumors was that of a schwannoma (seven of nine cases), and the remaining two cases showed features of a neurofibroma. One case, a schwannoma, recurred 4 years later and showed malignant transfi)rmation into a neurofibrosarcoma.
120
Surg Neurol 1992;37:118-22
Bhatia et al
Figure 2. Benign nerve sheath tumor u,ith prominent Verocay bodies (magnification × 367~.
The schwannomas showed distinct Antoni type A and type B areas. The type A areas were moderately cellular, with spindle-shaped cells arranged in a pallisading or organoid pattern. Formation of occasional Verocay bodies was noted (Figure 2). There was no mitosis. The type B areas showed polyhedral cells with vacuolated cytoplasm. Focal lymphocytic infilteration was also seen (Figure 3). Hyaline thickening of the blood vessels was frequently seen. The neurofibromas had sparse cellular components with abundant collagen fibers. The tumor cells had elongated nuclei with a wavy serpentine configuration and were pointed at both ends. The nerve sheath tumors were considered to be malignant when evidence of mitosis with or without necrosis was seen in the tissues. The neurofibrosarcomas had features of a nerve sheath origin. In addition the mitotic rate was increased, being 7 - 8 per 10 hpf in one case and 2 - 3 per 10 hpf in the other.
Results At the time of discharge five patients had improved and four were unchanged. Pain was relieved in all five patients and there was i m p r o v e m e n t in their walking. The sensory and m o t o r functions had improved to a variable degree. One patient who had required Dacron duraplasty developed meningitis secondary to a dural fistula from the wound and died. Seven patients returned for follow-up. Two of the four patients who had been unchanged at the time of discharge were lost to follow-up. The maximum follow-
up ranged from 4 months to 4 years in the remaining patients. Four patients showed remarkable improvement in their sensorimotor deficit and were left with only minimal residual disability. One patient with a predominant sacral and presacral tumor with predominant urinary disturbances did not show any significant improvement. Two patients were again operated on, at 4 years and at 15 months after the first operation. The former had recurrence of symptoms and a malignant transformation to a neurofibrosarcoma was histologically confirmed.
Discussion N e r v e sheath tumors of a large size are seen most often in the peripheral form of neurofibromatosis, as in plexiform neurofibromas or neurofibrosarcomas. H o w e v e r , intraspinal plexiform neurofibroma is a rare entity [20]. Large nerve sheath tumors in the spinal axis are uncommon [1,15,17]. A large series of studies of spinal neurofibromas does not mention this entity [3,9,10,16,22]. Although usually benign, they may sometimes be malignant or undergo a malignant transformation, especially in patients with neurofibromatosis [5,19]. Pain is a predominant feature in patients with cauda equina tumors of all sizes [1,9,10,17]. It is often worse on recumbency [ 14], with patients waking in the middle of the night with excruciating pain. The pain has a progressive course, unlike that of some patients with disk disease who have frequent remissions and relapses [9]. Benign tumors of the spinal column such as osteoid osteoma may also cause severe pain especially at night.
Giant Nerve Sheath Tumors
Surg Neurol 1992;37:118-22
121
Figure 3. Benign nerve sheath tumor with Antoni type B areas, showing cells with t,acuolated cytoplasm and areas of mild lymphocytic infiltration (magnification × 459).
These are characteristically relieved with aspirin [11]. Painless cauda equina tumors are extremely rare [4]. Only one of our patients had no pain. Abernathey et al [1], in their series of 13 cases of giant sacral schwannomas, described pain as the most important symptom. Gautier-Smith [ 10] reported pain in 33 of a series of 34 patients with lumbar neurofibromas. Rao [ 16] described clinical features of 23 patients with lumbar neurofibromas, 75% of whom had radiculopathy and almost all of whom had signs of m o t o r or sensory involvement. Only three patients in the series by Abernathey et al [1] had lower extremity sensorimotor defcit on examination. All the patients in the present series had sensorimotor deficit of variable severity. Autonomic disturbances are seen in 2 0 % - 5 0 ~ of patients [10,16]; they were present in six of our patients. While trauma and degenerative disease of the spine are the major causes of backache and radicular pain in the legs, occasionally patients with small intradural neurofibromas may present in a similar condition [21,23]. These patients do not show any changes on ~lain radiographs. The diagnosis is suggested by the aggravation of pain on recumbency and an elevated spinal fluid protein concentration. Focal bony changes, revealed in radiographs, suggest a spinal tumor has been seen in 4 0 ~ - 4 9 ~ of patients [6,13,16]. Focal erosion ofpedicles, enlarged intervertebral foramina, posterior scalloping, and widened interpedicular distance are some of the changes that have been observed. These changes were all localized and the tumors in all these cases were small. In the present series extensive bony changes were seen. T h e r e was widening of the interpedicular distances and scalloping of three or
four adjacent lumbar vertebrae, as well as thinning of the laminae. Extensive destruction of the anterior lumbosacral vertebra with intrapelvic extension of neurofibromas has been described [1,15,17]; this was also seen in two of our patients. Though usually benign histologically, these tumors may attain large proportions; they may even extend through the dura into the extradural tissues posteriorly and erode into the vertebral body and extend into the retroperitoneal space anteriorly, thereby presenting as an abdominal or pelvic mass. The gross appearance of these tumors at operation, the obvious infiltration into the dura and surrounding soft tissue, their extreme vascularity, and the fact that the nerve roots are intimately enmeshed in the tumor with no apparent attachment to any nerve root, all suggest the diagnosis of a malignant tumor of the cauda equina. Retroperitoneal or intrapelvic masses were seen in three patients. Only one of these had neurofibromatosis. Although these tumors are large and extensive and tend to transgress tissue planes, they are most often histologically benign, as was seen in all but one of our patients. One of the tumors underwent a malignant change and later recurred. Primary neurofibrosarcomas are often seen in patients with neurofibromatosis [ 19]. These are younger patients. Only one of our patients had a primary neurofibrosarcoma and this patient also had neurofibromatosis. Sacral neurofibrosarcomas are rare lesions in the absence of neurofibromatosis. Crosbie et al [5] have reported a case of sacral neurofibrosarcoma that was extending into the presacral region. On the basis of the bony changes alone it is usually
122
Surg Neurol 1992;37:118-22
not possible to differentiate a large benign neurofibroma from a neurofibrosarcoma. Besides large nerve sheath tumors and ependymomas, developmental tumors and metastatic deposits may present in a similar manner [9]. These patients may c o m e to the clinical attention o f a general surgeon, a gynecologist, an orthopedic surgeon, or a nephrologist. It is important to recognize that pain, weakness, and wasting o f the legs, as well as impotence and numbness in the perianal region, may herald an intraspinal cauda equina tumor [7].
Bhatia et al
10. Gautier-Smith PC. Clinical aspects of spinal neurofibromas. Brain 1967;90:359-94. I I. Keim HA. Low back pain. Ciba Clin Symp 1973: p 9. 12. Kernohan JW, Sayre GP. Tumors of the central nervous system (Atlas of Tumor Pathology, section 10, fascicles 35 and 37). Washington DC. Armed Forces Institute of Pathology, 1952: p 141. 13. Levy WJ, Latchaw J, Hahn JF, Sawhney B, Bay J, Dohn DF. Spinal neurofibromas: a report of 66 cases and a comparison with meningiomas. Neurosurgery 1986;18:331-4. 14. Milnes JN. The early diagnosis of tumors of the cauda equina. J Neurol Neurosurg Psychiatry 1953;16:158-65. 15. Osborn RE, DeWitt JD. Giant cauda equina schwannoma: CT appearance. Am J Neurosci Res 1985;6:835-6.
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