- Email: [email protected]
Chronic sciatica secondary to retroperitoneal pelvic schwannoma
108 Tong et al.
(3) Aberrant nests of cartilage forming cells in the dura mater.15 (4) Traumatic displacement of cartilage.1;14 All four histopathogenetic mechanisms could explain the existence of chondromas arising from the dura mater. Genuine dural chondroma is a rare condition and only a few papers have proposed histogenetic hypotheses. In our case the histopathogenesis is difficult to ascertain. We suggest the tumour originated from an intradurally located embryonal cartilaginous rest in the convexity dura mater. The clinical presentation of intracranial chondromas is not unique. Some of these lesions may progress to malignant degeneration and malignant degeneration has been reported in subtotally resected chondromas.4;10 Complete surgical resection is the treatment of choice together with the dural attachment. After complete removal, no recurrence should be expected and the literature reports a favourable long-term prognosis.12;17 Hardy et al. reported a patient with a 44 year survival after complete removal of a convexity chondroma.11 The dural chondroma presented in this study was well circumscribed, relatively avascular and found not to be adherent to surrounding tissues during surgery. These characteristics facilitated easy surgical excision. When chondromas are located on the convexity, surgery is easier in comparison to resection from other locations. The radiological findings of chondromas are non-specific.2;7 The rare incidence and non-specific radiological findings may result in difficulty with respect to preoperative diagnosis. Previous reports indicate that chondromas do not respond well to irradiation.2;18 Some authors suggest that, radiotherapy may increase malignant degeneration. Radiotherapy is therefore not recommended for residual tumour or non-operative cases.2;18;19 Chondromas have slow growth rates are radiological indistinguishable from other lesions and are easily surgically resected when on the convexity. Malignant degeneration should always be a matter for consideration.
16. Ahyai A, Spoerri O. Intracerebral chondroma. Surg Neurol 1979; 11: 431–433. € zgen T, Pamir MN, Akalan N et al. Intracranial soltary chondroma: case 17. O report. J Neurosurg 1984; 61: 399–401. 18. Russel DS, Rubinstein LJ. In: Pathology of tumors of the nervous system. 5th ed. Edward Arnold, London 1989; 471–818. 19. Falconer MA, Bailer IC, Duchan LW. Surgical treatment of chordoma and chondroma of skull base. J Neurosurg 1968; 26: 261–275.
Chronic sciatica secondary to retroperitoneal pelvic schwannoma Raymond S.K. Tong1, Neil Collier2, Andrew H. Kaye1,2 1 Department of Neurosurgery, The Royal Melbourne Hospital, Victoria, Australia, 2Department of Surgery, The Royal Melbourne Hospital, Victoria, Australia
Summary Pelvic schwannoma is a rare cause of sciatic pain. We report a case of retroperitoneal pelvic schwannoma presenting with chronic sciatica which was diagnosed and monitored radiologically for several years before successful surgical resection. ª 2002 Elsevier Science Ltd. All rights reserved. Journal of Clinical Neuroscience (2003) 10(1), 108–111 ª 2002 Elsevier Science Ltd. All rights reserved. DOI:10.1016/S0967-5868(02)00107-8
Keywords: pelvic schwannoma, neurilemmoma(s), retroperitoneum, sciatica, MRI Received 13 September 2001 Accepted 14 January 2002 Correspondence to: Dr Raymond S.K. Tong, 21 Clive Street, East Brighton, Victoria 3187, Australia. Tel./Fax: +61-03-9592-1326; E-mail: [email protected]
REFERENCES 1. Berkmen YM, Blatt ES. Cranial and intracranial cartilaginous tumors. Clin Radiol 1968; 19: 327–333. 2. Krayenb€ uhl H, Yasargil MG. Chondromas. Prog Neurol Surg 1975; 6: 453–463. 3. Kretzschmar HA, Eqger HR, Beck V et al. Intracranial chondroma: case report. Surg Neurol 1989; 32: 121–125. 4. Mapstone TB, Wangmongklorit T, Roessman U et al. Intradural chondroma: a case report and review of the literature. Neurosurgery 1983; 12: 112–114. 5. Ghogamala Z, Moore M, Strand R et al. Clival chondroma in child with ollierÕs disease: case report. Pediatr Neurosurg 1991; 17: 53–56. 6. Troflet RF, Barbaria AR, Borolat G, et al. Intracranial chondroma in a patient with ollierÕs disease: case report. 1989; 70: 270–274. 7. Terasaka S, Sawamura Y. Surgical removal of a cavernous sinus chondroma. Surg Neurol 1997; 48: 153–159. 8. Palacios SE. Intracranial solitary chondroma of dural origin. Am J Roentgenol 1970; 110: 67–70. 9. Acompora S, Troisi F, Fusco G et al. Voluminous intracranial chondroma. Surg Neurol 1982; 18: 254–257. 10. Kurt E, Beute GN, Sluzewski M et al. Giant chondroma of falx: case report and review of the literature. J Neurosurg 1996; 85: 1161–1164. 11. Hardy Jr RW, Benjamin SP, Gardner WJ. Prolonged survival following excision of dural chondroma: case report. J Neurosurg 1978; 48: 125–127. 12. Nakazoma T, Inove T, Suziki F et al. Solitary intracranial chondroma of the convexity dura: case report. Surg Neurol 1993; 40: 495–498. 13. Takano M, Oka H, Kawano N, Yada K, Yagishita S. Dural chondroma with fat tissue. Acta Neurochir (Wien) (AUSTRIA) 1997; 139(7): 690–691. 14. Chorobski J, Jarzymski J, Ferens E. Intracranial solitary chondroma. Surg Gynecol Obstet 1939; 68: 677–686. 15. Dutton J. Intracranial solitary chondroma: case report. J Neurosurg 1978; 49: 460–463.
Journal of Clinical Neuroscience (2003) 10(1)
INTRODUCTION Schwannomas (neurilemmomas) are benign neural sheath tumours which commonly arise from cranial nerves and cutaneous nerves of the head and neck. The most common site is the acoustic neuroma of the eighth cranial nerve. Pelvic schwannomas are rare and often present with non-specific symptoms leading to misdiagnosis and prolonged morbidity.1;2 Most cases of pelvic schwannoma have been reported in the gynaecological and urological literature due to their presentation as a pelvic mass or from urinary tract compression. We present a case of chronic sciatica caused by a retroperitoneal pelvic schwannoma and review the literature regarding its management.
CASE REPORT A 57-year-old female presented to our centre with a 6 year history of right-sided lower leg and foot pain. The pain was of a stabbing quality arising from under the right buttock and radiated down the posterolateral aspect of the thigh, leg and calf to the foot. It was associated with minimal lower back pain and her symptoms were made worst especially when she lay down at night and relieved when upright. There was no leg weakness or numbness. She had no bowel or urinary symptoms. The pain had began gradually 6 ª 2002 Elsevier Science Ltd. All rights reserved.
Sciatica secondary to schwannoma 109
years ago and was not associated with any trauma or injury. She had been previously well with no past medical problems. There was no family history or features of neurofibromatosis. Initial management had included physiotherapy and chiropractic treatments, without significant benefit. Magnetic resonance imaging (MRI) of the pelvis and lumbar–sacral spine revealed a well-defined round 2:9 2:2 cm soft tissue mass deep in the right pelvis, lying in the presacral space between the right sacroiliac joint and the rectum. The lower border of the lesion was adjacent to the upper edge of the right piriformis muscle. It appeared to arise from the first sacral nerve at the junction where it joins with other sacral nerves to become the right sciatic nerve (Fig. 1A). The lesion was isodense on T1 weighted imaging (Fig. 1A) and was hyperdense on T2 weighted imaging (Fig. 1B, C). There were areas of signal heterogeneity within the lesion on T2 weighted imaging which signified possible necrosis and degeneration (Fig. 1B). The surrounding soft tissue and organs were normal except for a bulky fibroid uterus. The appearance of the lesion on MRI was suggestive of a benign nerve sheath tumour with areas of degeneration arising from the first sacral nerve near the beginning of the right sciatic nerve. As the patientÕs symptoms were mild and the lesion was small, it was managed conservatively with analgesia and followup imaging. Computed tomography (CT) of the abdomen and pelvis was repeated every year for 2 years then every second year. The well-circumscribed lesion remained stable and did not change in size or appearance. There was no evidence of pelvic lymphadenopathy or any other abnormality. A focus of central calcification was seen within the lesion on CT which corresponded with areas of signal change suggestive of necrosis on T2 weighted MRI (Fig. 2). For the next 5 years her symptoms remained mild and did not progress. Six months before she was referred to our centre the pain became worse and she had significant difficulties with sleeping and walking. Another MRI was performed (Fig. 3) and
B Fig. 1B T2 weighted axial pelvic MRI showing a schwannoma with high signal intensity (C) lying adjacent to the right piriformis muscle (small arrows). Areas of signal change within the lesion. (D) are suggestive of degeneration.
C Fig. 1C T2 weighted sagittal pelvic MRI demonstrating a pelvic schwannoma in the presacral space with sacrum (E) posteriorly, rectum (F) and uterus (G) anteriorly.
A Fig. 1A T1 weighted coronal pelvic MRI demonstrating first the sacral nerve (A) giving rise to a well-circumscribed isodense lesion suggestive of a schwannoma (B) at the right sciatic notch.
ª 2002 Elsevier Science Ltd. All rights reserved.
no changes to the lesion were seen. Repeat examination showed good range of movement of the lumbar spine. Straight leg raise testing was normal to 80° bilaterally. Reflexes, power and sensation of the lower limbs were all normal. A CT lumbar myelogram was performed and revealed degenerative joint disease without any focal impingement of nerve roots. Laparotomy via a Pfannenstiel incision was performed. At surgery, the presacral tumour was found deep in the pelvis adjaJournal of Clinical Neuroscience (2003) 10(1)
110 Tong et al.
DISCUSSION
Fig. 2 Non-contrast CT image showing a pelvic schwannoma with a central area of calcification (H).
Fig. 3 Coronal MRI repeated 6 years after the first diagnosis indicating no change in the size of the lesion. Fat reduction imaging (T2 signal tau inversion recovery imaging) demonstrates the right first sacral nerve (I) giving rise to a pelvic schwannoma (J).
cent to the right sciatic notch. The retroperitoneum was divided and the rectum mobilised with preservation of the internal iliac vein which overlay the well-encapsulated mass. The tumour was not adherent to the right sciatic nerve and sacral nerves. It was excised completely without damage to the neural structures. The patient had an uneventful postoperative recovery with no neurological complications. She had immediate complete resolution of her symptoms which has persisted to the present time, 6 months since the time of surgery. Histopathology revealed a well-encapsulated tumour of interwoven spindle cell bundles with a moderate amount of chronic inflammatory infiltrate. There were areas of calcification and haemorrhage within the tumour. These features were typical of a degenerative schwannoma and this was confirmed on immunohistochemistry with component cells staining strongly for S-100 protein and occasionally for neurofilament protein. There were no features of malignancy. Journal of Clinical Neuroscience (2003) 10(1)
Pelvic schwannomas are rare and account for less than 1% of all benign schwannomas.3;4 They can range from a few millimetres to large tumours occupying most of the pelvis.5 Pelvic schwannomas may arise from lumbar and sacral nerves or from the proximal sciatic nerve. The majority of them are located in the presacral space, bordered by the rectum anteriorly, sacrum posteriorly, levator ani and coccygeal muscles inferiorly and the ureters and iliac vessels laterally. In a review of patients over 60 years at the Mayo clinic, 35 cases of neurogenic tumours of the sciatic nerve were found and only one case (3%) was of a benign schwannoma in the pelvis.6 Because of the anatomical position, many cases of pelvic schwannomas present late and at a large size with symptoms secondary to pressure on adjacent pelvic organs. Commonly this leads to vague pain in the lower back, abdomen and pelvis. Urinary and bowel symptoms are common from compression of the rectum and bladder. Incidental discovery at routine pelvic or rectal examination and on imaging can occur in asymptomatic cases. Gubbay et al. reported a case of obstructed labour caused by a large benign pelvic schwannoma which was discovered on emergency caesarean section.7 There are only a handful of reports of pelvic schwannomas causing sciatic pain down the lower limbs. Ball et al. reviewed 248 patients with primary soft tissue tumours of the pelvis and only 11 (4.4%) presented with referred leg pain. Out of the 11 tumours that had sciatica, only one case (0.4%) was of a benign pelvic schwannoma.1 Our case presented with sciatic pain radiating down the posterolateral aspect of the leg and foot corresponding to the first sacral nerve in which the lesion was found. The exacerbation of pain when lying down has been previously described.6 In our case it is possible that our patientÕs bulky fibroid uterus as well as other pelvic organs may have compressed the schwannoma onto the sacral nerves when supine. Pain may increase with straining or coughing as increased intraabdominal pressure leads to more pressure on the nerves.2 Presacral pelvic schwannomas may be palpated on rectal or pelvic examination and this may produce pain down the leg. As in most reports of pelvic schwannoma, our patient had no history of neurofibromatosis. In general, approximately 18% of all schwannomas are associated with neurofibromatosis.8 Schwannomas are composed of Schwann cells in the nerve sheath. Microscopically they can be divided into hypercellular bundles of spindle-shaped cells (Antoni A) and areas of lower cellularity, loose myxomatous arrangement of cells and fibres (Antoni B). Schwannomas can be confused with smooth muscle sarcomas and immunohistochemistry using S-100 protein and neurofilament stains may help to confirm the diagnosis. Malignant transformation in benign schwannoma is extremely rare.9 This is a unique case because the schwannoma was diagnosed preoperatively on MRI and monitored radiologically for several years before symptoms became significant. The tumour had radiological features consistent with previously reported pelvic schwannomas diagnosed preoperatively on MRI.10; 11 The lesion was well demarcated and on T1 weighted imaging had low to intermediate signal intensities similar to those of skeletal muscle. On T2 weighted imaging, the signal intensities were increased and there were heterogeneous areas of signal intensity indicating areas of degeneration. Anatomically, it appeared to arise from the first sacral nerve, suggesting a neural origin for this tumour. There was no change in size of the tumour over the 6 years of monitoring which is consistent with a slow-growing benign schwannoma. The timing of surgery for pelvic schwannomas which are diagnosed incidentally or with minimal symptoms is controversial.
ª 2002 Elsevier Science Ltd. All rights reserved.
Hamartoma in the internal auditory canal 111
If symptoms are not significant and radiology of the lesion show a small solitary tumour arising from neural structures with features suggestive of a benign schwannoma, it is probably appropriate to monitor the lesion radiologically and remove it when symptoms worsen or if it grows rapidly. In patients who have neurofibromatosis, benign pelvic schwannomas may be confused with neurofibromas which have an approximately 10% risk of malignant transformation.12 In most cases of neurofibroma, the lesions are multiple compared to solitary schwannomas. Resection should be attempted in these cases. Surgical resection of pelvic schwannomas is curative treatment. Schwannomas theoretically should be easily resectable and ‘‘shell out’’ of the capsule. Knowledge of the anatomy within the pelvis is essential as the tumour lies adjacent to vulnerable structures such as the iliac vessels, ureters and bladder. Larger tumours can involve the sacrum and may require an anterior transabdominal approach as well as a posterior trans-sacral resection.13 Laparoscopic resection of a preoperatively diagnosed pelvic schwannoma has been described but experience is limited.14 In conclusion, pelvic schwannoma is a rare cause of sciatica which has an excellent prognosis after surgical resection. Recurrence is associated with residual tumour and malignant transformation is very rare. Preoperative diagnosis of pelvic schwannomas is possible with MRI. Small lesions that do not produce significant symptoms may be monitored radiologically.
Department of Neurosurgery, Oita Medical University, 1-1 Idaigaoka, Hasama-machi, Oita 879-5593, Japan
Summary An 11 year old girl presented with hearing loss in her left ear and left trigeminal and facial nerve palsy. Radiological examinations revealed an enlargement of the left internal acoustic canal and the existence of a mass protruding from the canal into the cerebellopontine angle. The partial resection of the mass by a suboccipital craniectomy resulted in ceasing the progression of her symptoms. Histological diagnosis was hamartoma with cerebellar heterotopia. The concurrence of heterotopic cerebellar tissue could help to understand the pathogenesis of hamartomas. ª 2002 Elsevier Science Ltd. All rights reserved. Journal of Clinical Neuroscience (2003) 10(1), 111–113 ª 2002 Elsevier Science Ltd. All rights reserved. DOI:10.1016/S0967-5868(02)00265-5
Keywords: intrameatal tumor, acoustic neurinoma, hamartoma, cerebellar heterotopia Received 11 September 2001 Accepted 18 December 2001 Correspondence to: Mitsuo Isono MD, PhD, Department of Neurosurgery, Oita Medical University, 1-1 Idaigaoka, Hasama-machi, Oita 879-5593, Japan. Tel.: +81-975-86-5860; Fax: +81-975-86-5869; E-mail: [email protected]
REFERENCES 1. Ball A, Serpell JW, Fisher C, Thomas JM. Primary soft tissue tumours of the pelvis causing referred pain in the leg. J Surg Oncol 1991; 47: 17–20. 2. Kelso TB, Ferrari CJ, Frassica FJ. Sciatica caused by a neurilemmoma of the intrapelvic portion of the sciatic nerve. J Bone Joint Surg Am 1993; 75: 603–605. 3. Felix EL, Wood DK, Das Gupta TK. Tumours of the retroperitoneum. Curr Prob Cancer 1981; 6: 1. 4. Guz BV, Wood DP, Montie JE, Pontes JE. Retroperitoneal neural sheath tumours: Cleveland Clinic experience. J Urol 1989; 142: 1434–1437. 5. Acciarri N, Staffa G, Poppi M. Giant sacral schwannoma: removal by an anterior transabdominal approach. Br J Neurosurg 1996; 10: 489–492. 6. Thomas JE, Piepgras DG, Scheithauer B, Onofrio BM, Shives TC. Neurogenic tumours of the sciatic nerve: a clinicopathologic study of 35 cases. Mayo Clin Proc 1983; 58: 640–647. 7. Gubbay AD, Moshilla G, Gray BN, Thompson I. Retroperitoneal schwannoma: a case series and review. Aust NZ J Surg 1995; 65: 197–200. 8. Enzinger FM, Weiss SW. In: Soft tissue tumours. 3rd ed. Mosby, St. Louis, MO 1995: 829. 9. Woodruff JM, Selig AM, Crowley K, Allen PW. Schwannoma (neurilemmoma) with malignant transformation. A rare, distinctive peripheral nerve tumour. Am J Surg Pathol 1994; 18: 882–895. 10. Nasu K, Arima K, Yoshimatsu J, Miyakawa I. CT and MRI findings in a case of pelvic schwannoma. Gynaecol Obstet Invest 1998; 46: 142–144. 11. Kim SH, Choi BI, Han MC, Kim YI. Retroperitoneal neurilemmoma: CT and MR findings. Am J Roentgenol 1992; 159: 1023–1026. 12. Kaye AH. In: Essential neurosurgery. 2nd ed. Edinburgh: Churchill Livingstone, 1997; 360. 13. Localio SA, Eng K, Ranson JH. Abdominosacral approach for retrorectal tumours. Ann Surg 1980; 191: 555–560. 14. Melvin WS. Laparoscopic resection of a pelvic schwannoma. Surg Laparosc Endosc 1996; 6: 489–491.
Hamartoma in the internal auditory canal Makoto Goda MD PHD, Mitsuo Isono MD PHD, Atsushi Karashima MD PHD, Naoto Kasai MD PHD, Hidenori Kobayashi MD PHD ª 2002 Elsevier Science Ltd. All rights reserved.
INTRODUCTION Hamartomas are relatively rare but may be encountered in the midline structure in central nervous systems. In this report we describe a patient with a hamartoma in the internal auditory canal. This condition seems to be quite rare, but the histological findings in this case are interesting and might help to elucidate the pathogenesis of this congenital malformation.
CASE REPORT An 11 year old girl was admitted with progressive hearing loss in the left ear and left facial palsy. She had begun to have hearing impairment in the left ear 3 years before admission. She had sudden onset of headache and vomiting. Four days later she had left facial palsy and began to feel numbness in the left side of her face. On admission the neurological examination revealed complete hearing loss in the left ear, incomplete palsy of the left facial nerve and slight hypesthesia in the area of the left trigeminal nerve. An audiogram showed flat sensorioneuronal hearing loss and an auditory brainstem response was negative. However, her vestibular functions were normal and she showed no signs of ataxia. Motor weakness was observed in all the facial muscles on the left side, but was more prominent in the lower half of the face than in the upper half. The lacrimal secretion was disturbed. There was equal slight hypesthesia in the entire area of the left trigeminal nerve. There were no other abnormal findings. Computed tomography (CT) showed a dilated left internal acoustic canal, but did not show an abnormally enhanced mass in the cerebellopontine angle (Fig. 1). Air CT cisternography indicated the existence of an isodense mass protruding from the canal into the cerebellopontine cistern (Fig. 2). Cerebral angiography revealed no abnormality. Six weeks later a diagnosis of intrameatal acoustic neurinoma was made and a left suboccipital craniectomy was performed. The dissection of a thickened arachnoid membrane around the cerebellopontine cistern revealed a dark red soft mass protruding from Journal of Clinical Neuroscience (2003) 10(1)
(3) Aberrant nests of cartilage forming cells in the dura mater.15 (4) Traumatic displacement of cartilage.1;14 All four histopathogenetic mechanisms could explain the existence of chondromas arising from the dura mater. Genuine dural chondroma is a rare condition and only a few papers have proposed histogenetic hypotheses. In our case the histopathogenesis is difficult to ascertain. We suggest the tumour originated from an intradurally located embryonal cartilaginous rest in the convexity dura mater. The clinical presentation of intracranial chondromas is not unique. Some of these lesions may progress to malignant degeneration and malignant degeneration has been reported in subtotally resected chondromas.4;10 Complete surgical resection is the treatment of choice together with the dural attachment. After complete removal, no recurrence should be expected and the literature reports a favourable long-term prognosis.12;17 Hardy et al. reported a patient with a 44 year survival after complete removal of a convexity chondroma.11 The dural chondroma presented in this study was well circumscribed, relatively avascular and found not to be adherent to surrounding tissues during surgery. These characteristics facilitated easy surgical excision. When chondromas are located on the convexity, surgery is easier in comparison to resection from other locations. The radiological findings of chondromas are non-specific.2;7 The rare incidence and non-specific radiological findings may result in difficulty with respect to preoperative diagnosis. Previous reports indicate that chondromas do not respond well to irradiation.2;18 Some authors suggest that, radiotherapy may increase malignant degeneration. Radiotherapy is therefore not recommended for residual tumour or non-operative cases.2;18;19 Chondromas have slow growth rates are radiological indistinguishable from other lesions and are easily surgically resected when on the convexity. Malignant degeneration should always be a matter for consideration.
16. Ahyai A, Spoerri O. Intracerebral chondroma. Surg Neurol 1979; 11: 431–433. € zgen T, Pamir MN, Akalan N et al. Intracranial soltary chondroma: case 17. O report. J Neurosurg 1984; 61: 399–401. 18. Russel DS, Rubinstein LJ. In: Pathology of tumors of the nervous system. 5th ed. Edward Arnold, London 1989; 471–818. 19. Falconer MA, Bailer IC, Duchan LW. Surgical treatment of chordoma and chondroma of skull base. J Neurosurg 1968; 26: 261–275.
Chronic sciatica secondary to retroperitoneal pelvic schwannoma Raymond S.K. Tong1, Neil Collier2, Andrew H. Kaye1,2 1 Department of Neurosurgery, The Royal Melbourne Hospital, Victoria, Australia, 2Department of Surgery, The Royal Melbourne Hospital, Victoria, Australia
Summary Pelvic schwannoma is a rare cause of sciatic pain. We report a case of retroperitoneal pelvic schwannoma presenting with chronic sciatica which was diagnosed and monitored radiologically for several years before successful surgical resection. ª 2002 Elsevier Science Ltd. All rights reserved. Journal of Clinical Neuroscience (2003) 10(1), 108–111 ª 2002 Elsevier Science Ltd. All rights reserved. DOI:10.1016/S0967-5868(02)00107-8
Keywords: pelvic schwannoma, neurilemmoma(s), retroperitoneum, sciatica, MRI Received 13 September 2001 Accepted 14 January 2002 Correspondence to: Dr Raymond S.K. Tong, 21 Clive Street, East Brighton, Victoria 3187, Australia. Tel./Fax: +61-03-9592-1326; E-mail: [email protected]
REFERENCES 1. Berkmen YM, Blatt ES. Cranial and intracranial cartilaginous tumors. Clin Radiol 1968; 19: 327–333. 2. Krayenb€ uhl H, Yasargil MG. Chondromas. Prog Neurol Surg 1975; 6: 453–463. 3. Kretzschmar HA, Eqger HR, Beck V et al. Intracranial chondroma: case report. Surg Neurol 1989; 32: 121–125. 4. Mapstone TB, Wangmongklorit T, Roessman U et al. Intradural chondroma: a case report and review of the literature. Neurosurgery 1983; 12: 112–114. 5. Ghogamala Z, Moore M, Strand R et al. Clival chondroma in child with ollierÕs disease: case report. Pediatr Neurosurg 1991; 17: 53–56. 6. Troflet RF, Barbaria AR, Borolat G, et al. Intracranial chondroma in a patient with ollierÕs disease: case report. 1989; 70: 270–274. 7. Terasaka S, Sawamura Y. Surgical removal of a cavernous sinus chondroma. Surg Neurol 1997; 48: 153–159. 8. Palacios SE. Intracranial solitary chondroma of dural origin. Am J Roentgenol 1970; 110: 67–70. 9. Acompora S, Troisi F, Fusco G et al. Voluminous intracranial chondroma. Surg Neurol 1982; 18: 254–257. 10. Kurt E, Beute GN, Sluzewski M et al. Giant chondroma of falx: case report and review of the literature. J Neurosurg 1996; 85: 1161–1164. 11. Hardy Jr RW, Benjamin SP, Gardner WJ. Prolonged survival following excision of dural chondroma: case report. J Neurosurg 1978; 48: 125–127. 12. Nakazoma T, Inove T, Suziki F et al. Solitary intracranial chondroma of the convexity dura: case report. Surg Neurol 1993; 40: 495–498. 13. Takano M, Oka H, Kawano N, Yada K, Yagishita S. Dural chondroma with fat tissue. Acta Neurochir (Wien) (AUSTRIA) 1997; 139(7): 690–691. 14. Chorobski J, Jarzymski J, Ferens E. Intracranial solitary chondroma. Surg Gynecol Obstet 1939; 68: 677–686. 15. Dutton J. Intracranial solitary chondroma: case report. J Neurosurg 1978; 49: 460–463.
Journal of Clinical Neuroscience (2003) 10(1)
INTRODUCTION Schwannomas (neurilemmomas) are benign neural sheath tumours which commonly arise from cranial nerves and cutaneous nerves of the head and neck. The most common site is the acoustic neuroma of the eighth cranial nerve. Pelvic schwannomas are rare and often present with non-specific symptoms leading to misdiagnosis and prolonged morbidity.1;2 Most cases of pelvic schwannoma have been reported in the gynaecological and urological literature due to their presentation as a pelvic mass or from urinary tract compression. We present a case of chronic sciatica caused by a retroperitoneal pelvic schwannoma and review the literature regarding its management.
CASE REPORT A 57-year-old female presented to our centre with a 6 year history of right-sided lower leg and foot pain. The pain was of a stabbing quality arising from under the right buttock and radiated down the posterolateral aspect of the thigh, leg and calf to the foot. It was associated with minimal lower back pain and her symptoms were made worst especially when she lay down at night and relieved when upright. There was no leg weakness or numbness. She had no bowel or urinary symptoms. The pain had began gradually 6 ª 2002 Elsevier Science Ltd. All rights reserved.
Sciatica secondary to schwannoma 109
years ago and was not associated with any trauma or injury. She had been previously well with no past medical problems. There was no family history or features of neurofibromatosis. Initial management had included physiotherapy and chiropractic treatments, without significant benefit. Magnetic resonance imaging (MRI) of the pelvis and lumbar–sacral spine revealed a well-defined round 2:9 2:2 cm soft tissue mass deep in the right pelvis, lying in the presacral space between the right sacroiliac joint and the rectum. The lower border of the lesion was adjacent to the upper edge of the right piriformis muscle. It appeared to arise from the first sacral nerve at the junction where it joins with other sacral nerves to become the right sciatic nerve (Fig. 1A). The lesion was isodense on T1 weighted imaging (Fig. 1A) and was hyperdense on T2 weighted imaging (Fig. 1B, C). There were areas of signal heterogeneity within the lesion on T2 weighted imaging which signified possible necrosis and degeneration (Fig. 1B). The surrounding soft tissue and organs were normal except for a bulky fibroid uterus. The appearance of the lesion on MRI was suggestive of a benign nerve sheath tumour with areas of degeneration arising from the first sacral nerve near the beginning of the right sciatic nerve. As the patientÕs symptoms were mild and the lesion was small, it was managed conservatively with analgesia and followup imaging. Computed tomography (CT) of the abdomen and pelvis was repeated every year for 2 years then every second year. The well-circumscribed lesion remained stable and did not change in size or appearance. There was no evidence of pelvic lymphadenopathy or any other abnormality. A focus of central calcification was seen within the lesion on CT which corresponded with areas of signal change suggestive of necrosis on T2 weighted MRI (Fig. 2). For the next 5 years her symptoms remained mild and did not progress. Six months before she was referred to our centre the pain became worse and she had significant difficulties with sleeping and walking. Another MRI was performed (Fig. 3) and
B Fig. 1B T2 weighted axial pelvic MRI showing a schwannoma with high signal intensity (C) lying adjacent to the right piriformis muscle (small arrows). Areas of signal change within the lesion. (D) are suggestive of degeneration.
C Fig. 1C T2 weighted sagittal pelvic MRI demonstrating a pelvic schwannoma in the presacral space with sacrum (E) posteriorly, rectum (F) and uterus (G) anteriorly.
A Fig. 1A T1 weighted coronal pelvic MRI demonstrating first the sacral nerve (A) giving rise to a well-circumscribed isodense lesion suggestive of a schwannoma (B) at the right sciatic notch.
ª 2002 Elsevier Science Ltd. All rights reserved.
no changes to the lesion were seen. Repeat examination showed good range of movement of the lumbar spine. Straight leg raise testing was normal to 80° bilaterally. Reflexes, power and sensation of the lower limbs were all normal. A CT lumbar myelogram was performed and revealed degenerative joint disease without any focal impingement of nerve roots. Laparotomy via a Pfannenstiel incision was performed. At surgery, the presacral tumour was found deep in the pelvis adjaJournal of Clinical Neuroscience (2003) 10(1)
110 Tong et al.
DISCUSSION
Fig. 2 Non-contrast CT image showing a pelvic schwannoma with a central area of calcification (H).
Fig. 3 Coronal MRI repeated 6 years after the first diagnosis indicating no change in the size of the lesion. Fat reduction imaging (T2 signal tau inversion recovery imaging) demonstrates the right first sacral nerve (I) giving rise to a pelvic schwannoma (J).
cent to the right sciatic notch. The retroperitoneum was divided and the rectum mobilised with preservation of the internal iliac vein which overlay the well-encapsulated mass. The tumour was not adherent to the right sciatic nerve and sacral nerves. It was excised completely without damage to the neural structures. The patient had an uneventful postoperative recovery with no neurological complications. She had immediate complete resolution of her symptoms which has persisted to the present time, 6 months since the time of surgery. Histopathology revealed a well-encapsulated tumour of interwoven spindle cell bundles with a moderate amount of chronic inflammatory infiltrate. There were areas of calcification and haemorrhage within the tumour. These features were typical of a degenerative schwannoma and this was confirmed on immunohistochemistry with component cells staining strongly for S-100 protein and occasionally for neurofilament protein. There were no features of malignancy. Journal of Clinical Neuroscience (2003) 10(1)
Pelvic schwannomas are rare and account for less than 1% of all benign schwannomas.3;4 They can range from a few millimetres to large tumours occupying most of the pelvis.5 Pelvic schwannomas may arise from lumbar and sacral nerves or from the proximal sciatic nerve. The majority of them are located in the presacral space, bordered by the rectum anteriorly, sacrum posteriorly, levator ani and coccygeal muscles inferiorly and the ureters and iliac vessels laterally. In a review of patients over 60 years at the Mayo clinic, 35 cases of neurogenic tumours of the sciatic nerve were found and only one case (3%) was of a benign schwannoma in the pelvis.6 Because of the anatomical position, many cases of pelvic schwannomas present late and at a large size with symptoms secondary to pressure on adjacent pelvic organs. Commonly this leads to vague pain in the lower back, abdomen and pelvis. Urinary and bowel symptoms are common from compression of the rectum and bladder. Incidental discovery at routine pelvic or rectal examination and on imaging can occur in asymptomatic cases. Gubbay et al. reported a case of obstructed labour caused by a large benign pelvic schwannoma which was discovered on emergency caesarean section.7 There are only a handful of reports of pelvic schwannomas causing sciatic pain down the lower limbs. Ball et al. reviewed 248 patients with primary soft tissue tumours of the pelvis and only 11 (4.4%) presented with referred leg pain. Out of the 11 tumours that had sciatica, only one case (0.4%) was of a benign pelvic schwannoma.1 Our case presented with sciatic pain radiating down the posterolateral aspect of the leg and foot corresponding to the first sacral nerve in which the lesion was found. The exacerbation of pain when lying down has been previously described.6 In our case it is possible that our patientÕs bulky fibroid uterus as well as other pelvic organs may have compressed the schwannoma onto the sacral nerves when supine. Pain may increase with straining or coughing as increased intraabdominal pressure leads to more pressure on the nerves.2 Presacral pelvic schwannomas may be palpated on rectal or pelvic examination and this may produce pain down the leg. As in most reports of pelvic schwannoma, our patient had no history of neurofibromatosis. In general, approximately 18% of all schwannomas are associated with neurofibromatosis.8 Schwannomas are composed of Schwann cells in the nerve sheath. Microscopically they can be divided into hypercellular bundles of spindle-shaped cells (Antoni A) and areas of lower cellularity, loose myxomatous arrangement of cells and fibres (Antoni B). Schwannomas can be confused with smooth muscle sarcomas and immunohistochemistry using S-100 protein and neurofilament stains may help to confirm the diagnosis. Malignant transformation in benign schwannoma is extremely rare.9 This is a unique case because the schwannoma was diagnosed preoperatively on MRI and monitored radiologically for several years before symptoms became significant. The tumour had radiological features consistent with previously reported pelvic schwannomas diagnosed preoperatively on MRI.10; 11 The lesion was well demarcated and on T1 weighted imaging had low to intermediate signal intensities similar to those of skeletal muscle. On T2 weighted imaging, the signal intensities were increased and there were heterogeneous areas of signal intensity indicating areas of degeneration. Anatomically, it appeared to arise from the first sacral nerve, suggesting a neural origin for this tumour. There was no change in size of the tumour over the 6 years of monitoring which is consistent with a slow-growing benign schwannoma. The timing of surgery for pelvic schwannomas which are diagnosed incidentally or with minimal symptoms is controversial.
ª 2002 Elsevier Science Ltd. All rights reserved.
Hamartoma in the internal auditory canal 111
If symptoms are not significant and radiology of the lesion show a small solitary tumour arising from neural structures with features suggestive of a benign schwannoma, it is probably appropriate to monitor the lesion radiologically and remove it when symptoms worsen or if it grows rapidly. In patients who have neurofibromatosis, benign pelvic schwannomas may be confused with neurofibromas which have an approximately 10% risk of malignant transformation.12 In most cases of neurofibroma, the lesions are multiple compared to solitary schwannomas. Resection should be attempted in these cases. Surgical resection of pelvic schwannomas is curative treatment. Schwannomas theoretically should be easily resectable and ‘‘shell out’’ of the capsule. Knowledge of the anatomy within the pelvis is essential as the tumour lies adjacent to vulnerable structures such as the iliac vessels, ureters and bladder. Larger tumours can involve the sacrum and may require an anterior transabdominal approach as well as a posterior trans-sacral resection.13 Laparoscopic resection of a preoperatively diagnosed pelvic schwannoma has been described but experience is limited.14 In conclusion, pelvic schwannoma is a rare cause of sciatica which has an excellent prognosis after surgical resection. Recurrence is associated with residual tumour and malignant transformation is very rare. Preoperative diagnosis of pelvic schwannomas is possible with MRI. Small lesions that do not produce significant symptoms may be monitored radiologically.
Department of Neurosurgery, Oita Medical University, 1-1 Idaigaoka, Hasama-machi, Oita 879-5593, Japan
Summary An 11 year old girl presented with hearing loss in her left ear and left trigeminal and facial nerve palsy. Radiological examinations revealed an enlargement of the left internal acoustic canal and the existence of a mass protruding from the canal into the cerebellopontine angle. The partial resection of the mass by a suboccipital craniectomy resulted in ceasing the progression of her symptoms. Histological diagnosis was hamartoma with cerebellar heterotopia. The concurrence of heterotopic cerebellar tissue could help to understand the pathogenesis of hamartomas. ª 2002 Elsevier Science Ltd. All rights reserved. Journal of Clinical Neuroscience (2003) 10(1), 111–113 ª 2002 Elsevier Science Ltd. All rights reserved. DOI:10.1016/S0967-5868(02)00265-5
Keywords: intrameatal tumor, acoustic neurinoma, hamartoma, cerebellar heterotopia Received 11 September 2001 Accepted 18 December 2001 Correspondence to: Mitsuo Isono MD, PhD, Department of Neurosurgery, Oita Medical University, 1-1 Idaigaoka, Hasama-machi, Oita 879-5593, Japan. Tel.: +81-975-86-5860; Fax: +81-975-86-5869; E-mail: [email protected]
REFERENCES 1. Ball A, Serpell JW, Fisher C, Thomas JM. Primary soft tissue tumours of the pelvis causing referred pain in the leg. J Surg Oncol 1991; 47: 17–20. 2. Kelso TB, Ferrari CJ, Frassica FJ. Sciatica caused by a neurilemmoma of the intrapelvic portion of the sciatic nerve. J Bone Joint Surg Am 1993; 75: 603–605. 3. Felix EL, Wood DK, Das Gupta TK. Tumours of the retroperitoneum. Curr Prob Cancer 1981; 6: 1. 4. Guz BV, Wood DP, Montie JE, Pontes JE. Retroperitoneal neural sheath tumours: Cleveland Clinic experience. J Urol 1989; 142: 1434–1437. 5. Acciarri N, Staffa G, Poppi M. Giant sacral schwannoma: removal by an anterior transabdominal approach. Br J Neurosurg 1996; 10: 489–492. 6. Thomas JE, Piepgras DG, Scheithauer B, Onofrio BM, Shives TC. Neurogenic tumours of the sciatic nerve: a clinicopathologic study of 35 cases. Mayo Clin Proc 1983; 58: 640–647. 7. Gubbay AD, Moshilla G, Gray BN, Thompson I. Retroperitoneal schwannoma: a case series and review. Aust NZ J Surg 1995; 65: 197–200. 8. Enzinger FM, Weiss SW. In: Soft tissue tumours. 3rd ed. Mosby, St. Louis, MO 1995: 829. 9. Woodruff JM, Selig AM, Crowley K, Allen PW. Schwannoma (neurilemmoma) with malignant transformation. A rare, distinctive peripheral nerve tumour. Am J Surg Pathol 1994; 18: 882–895. 10. Nasu K, Arima K, Yoshimatsu J, Miyakawa I. CT and MRI findings in a case of pelvic schwannoma. Gynaecol Obstet Invest 1998; 46: 142–144. 11. Kim SH, Choi BI, Han MC, Kim YI. Retroperitoneal neurilemmoma: CT and MR findings. Am J Roentgenol 1992; 159: 1023–1026. 12. Kaye AH. In: Essential neurosurgery. 2nd ed. Edinburgh: Churchill Livingstone, 1997; 360. 13. Localio SA, Eng K, Ranson JH. Abdominosacral approach for retrorectal tumours. Ann Surg 1980; 191: 555–560. 14. Melvin WS. Laparoscopic resection of a pelvic schwannoma. Surg Laparosc Endosc 1996; 6: 489–491.
Hamartoma in the internal auditory canal Makoto Goda MD PHD, Mitsuo Isono MD PHD, Atsushi Karashima MD PHD, Naoto Kasai MD PHD, Hidenori Kobayashi MD PHD ª 2002 Elsevier Science Ltd. All rights reserved.
INTRODUCTION Hamartomas are relatively rare but may be encountered in the midline structure in central nervous systems. In this report we describe a patient with a hamartoma in the internal auditory canal. This condition seems to be quite rare, but the histological findings in this case are interesting and might help to elucidate the pathogenesis of this congenital malformation.
CASE REPORT An 11 year old girl was admitted with progressive hearing loss in the left ear and left facial palsy. She had begun to have hearing impairment in the left ear 3 years before admission. She had sudden onset of headache and vomiting. Four days later she had left facial palsy and began to feel numbness in the left side of her face. On admission the neurological examination revealed complete hearing loss in the left ear, incomplete palsy of the left facial nerve and slight hypesthesia in the area of the left trigeminal nerve. An audiogram showed flat sensorioneuronal hearing loss and an auditory brainstem response was negative. However, her vestibular functions were normal and she showed no signs of ataxia. Motor weakness was observed in all the facial muscles on the left side, but was more prominent in the lower half of the face than in the upper half. The lacrimal secretion was disturbed. There was equal slight hypesthesia in the entire area of the left trigeminal nerve. There were no other abnormal findings. Computed tomography (CT) showed a dilated left internal acoustic canal, but did not show an abnormally enhanced mass in the cerebellopontine angle (Fig. 1). Air CT cisternography indicated the existence of an isodense mass protruding from the canal into the cerebellopontine cistern (Fig. 2). Cerebral angiography revealed no abnormality. Six weeks later a diagnosis of intrameatal acoustic neurinoma was made and a left suboccipital craniectomy was performed. The dissection of a thickened arachnoid membrane around the cerebellopontine cistern revealed a dark red soft mass protruding from Journal of Clinical Neuroscience (2003) 10(1)