Case Report
Spinal Intradural Aneurysmal Bone Cyst: A Case Report Muthana Sartawi1, Ahmed Quateen2, Andrew Nataraj3, Robert Medairos4
Key words Aneurysmal bone cyst - Complete surgical resection - Extraosseous - Intradural - Vascular channels -
Abbreviations and Acronyms ABC: Aneurysmal bone Cyst MRI: Magnetic resonance imaging From the 1Department of Orthopedics, Dalhousie University, Nova Scotia, Canada; 2Mackenzie Health Sciences Centre and 3Department of Neurosurgery, University of Alberta, Alberta, Canada; and 4Rush Medical College, Chicago, Illinois, USA To whom correspondence should be addressed: Muthana Sartawi, BS.c., M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2015). http://dx.doi.org/10.1016/j.wneu.2015.02.012 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
INTRODUCTION Aneurysmal bone cyst (ABC) is an expanding osteolytic benign lesion accounting for approximately 1%e2% of all bone tumors (1). ABCs often occur within the first 2 decades of life, predominately located in the long bones and spine (2). Despite their benign nature, patients with spinal ABCs often present with pain and neurologic deficits caused by local obstruction and invasion into the surrounding tissue (2). To our knowledge, we report the first presentation of an extraosseous ABC involving the intradural extra-medullary spinal canal. CASE REPORT A 55-year-old healthy farm worker presented with 4 months of chest and back pain and 3 weeks of progressive leg pain and weakness. There was no numbness or
changes in bladder or bowel function. There were no constitutional symptoms and no significant medical history. On examination, he had grade 4/5 power bilaterally in his hip flexors. His power was otherwise intact, with normal reflexes and rectal tone. Sensory examination was normal except for diminished light touch sensation in the T7 dermatome. Gait analysis was prohibited by pain. Findings on magnetic resonance imaging (MRI) revealed an enhancing intradural extra-medullary lesion posterior to the T7 vertebral body, with significant spinal cord compression (Figure 1) but without involvement of the adjacent vertebral bodies. The lesion was of heterogeneous hyperintensity both on T1 and T2 imaging and also enhanced heterogeneously after gadolinium administration. We thought there either was hemorrhage or proteinaceous debris within the tumor. No fluid-fluid levels were identified. Dexamethasone was started, but the patient deteriorated over the subsequent 2 days to having grade 3/5 power in all lower limb myotomes. He was therefore taken for urgent surgery. A midline skin incision was made with exposure of the transverse processes and proximal ribs of T6 T8 on the right. Because of concern regarding tumor adherence to the anterior aspect of the spinal cord and visualization of such, in addition to a laminectomy, resection of the right transverse processes and posterior pedicle of T7 also was performed with disarticulation of the rib head. A ‘T’-shaped durotomy was made, with the horizontal aspect of this extending as far laterally as could be closed, given the bony exposure. The dentate ligament and left T7 root were divided. With the lateral bony structures removed, the tumor and lateral aspect of the spinal cord was visualized. The tumor was identified as a fleshy, purple mass, which was friable and non-adherent to the spinal cord. There
WORLD NEUROSURGERY - [-]: ---, MONTH 2015
was no obvious hemorrhage within it. Total excision was attempted, with tumor resection guided by intraoperative ultrasound and electrophysiological monitoring. It had indistinct margins, and we had difficulty assessing the extent of our resection ventromedially. There were several episodes of decreased motor evoked potentials, returning to baseline (which was impaired) after hypertensive therapy and time without tumor manipulation. Because the appearance of the tumor was somewhat unusual for either a meningioma or schwannoma, the ventrolateral extradural space and dura was also inspected after dural closure, without any abnormal appearing tissue found. Initially postoperatively, the patient’s pain improved and his power returned to a grade 4/5. He became ambulatory with a walker (similar to admission, but better than immediately pre-operatively). Histologically, it was a benign fibroosseous lesion with compact sheets of spindled cells and foci of newly formed bony trabecular lined by osteoblasts and telangectatic arrays of thin walled vascular channels (Figure 2). There were accompanying zones of recent hemorrhage in different stages of resorption. Clusters of multinucleated giant cells were scattered sporadically in the fibrous matrix. Mitotic figures were not observed. The pathologic diagnosis was an ABC. There were no areas of suspicion of concurrent neoplasm. The lesion was reviewed histologically at another institution (see Acknowledgements) for a second opinion, and corroborated our findings. At 6 months’ follow-up, the patient had minimal pain, and he was neurologically intact and fully ambulatory. At 54 months, he was neurologically intact without significant back pain and was able to participate in full activities. Imaging did not reveal any evidence of recurrent tumor. There was an increase in kyphosis of approximately 15 degrees over the first year of follow-up, but given the
www.WORLDNEUROSURGERY.org
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CASE REPORT MUTHANA SARTAWI ET AL.
SPINAL INTRADURAL ANEURYSMAL BONE CYST
Figure 1. Preoperative magnetic resonance imaging. Posterior to the T7 vertebral body, there is an area of heterogeneous increased T1 and T2 signal seen in intimate association with the anterior aspect of the spinal cord. This lesion demonstrates acute angles with the spinal cord superiorly and inferiorly. It exhibits dense peripheral enhancement, is slightly more centered to the left, and measures 2.0 cm (craniocaudad) by 0.7 cm (anterior-posterior) by 1.2 cm (transverse). The spinal cord at this level measures as little as 34 mm in thickness. However, no convincing cord edema is seen. In (C), the line indicates the level from which the preoperative axial sections (D G) are taken. T1-weighted sagittal (A), T1-weighted post-gadolinium (GAD); (B) T2-weighted sagittal (C); Axial T1-weighted turbo spin echo (TSE) (D) T1-weighted post-GAD; (E) T1-weighted fast spin echo (FSE) post-GAD; (F) T2-weighted (G).
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CASE REPORT MUTHANA SARTAWI ET AL.
Figure 2. A portion of tumor showing features of aneursymal bone cyst with foci of vascular spaces (v), radial arrays of osseous trabecular (o), and compact stoma (s). Medium magnification showing various sized vascular channels (v) in a fibrous matrix containing giant cells (arrows) and irregular osseous trabecular (o).
lack of symptoms, the patient was continued to be followed. There was no kyphosis beyond this at 54 months (Figure 3). DISCUSSION ABCs were historically described by Van Arsdale in 1893 as ossifying hematomas (3, 24). In 1942, the term “aneurysmal bone cyst” originated after 2 case reports of “peculiar blood-containing cysts of large size” (4). Our case is the first presentation of an extraosseous ABC involving the intradural extramedullary spinal canal.
SPINAL INTRADURAL ANEURYSMAL BONE CYST
The first reported intradural ABCs were intracranial, first in the cerebellopontine angle of a 25-year-old man (5), then along the sphenoid wing (6). There have been 13 other reports of extraosseous soft tissue ABCs (7). Our patient’s presentation was consistent with clinical features of other spinal ABCs, which include back pain, tenderness, and variable neurological deficits (8). Pathologic misdiagnosis for extraosseous ABCs include soft-tissue neoplasms such as extraskeletal osteosarcoma or ossifying fibromyxoid tumor, and nodular fasciitis with osteoclastic giant cells (9). Although our case did not have immunohistochemistry performed, we did have the histology reviewed at another institution (see Acknowledgements). Despite claims for potential markers to differentiate ABCs, no current system exists to confirm its diagnosis with immunohistochemical staining (10). There are several theories concerning the pathophysiology of intradural extraosseous ABCs primarily attributed to local hemodynamic disturbances. Postulated etiologies of ABCs include posttraumatic improper repair of subperiosteal hemorrhage, disturbance of bone vascularity, and hemorrhage into a preexisting lesion (11). Undiagnosed endocrine disorders or trauma have been speculated as potential causes of intradural-limited ossification (12). The radiological appearance in our patients was atypical for either schwannoma or meningioma. With varied hyperintensity on both T1 and T2 sequences, hemorrhage was suspected. However, there were no fluid-fluid levels that are pathognomonic for ABCs (13). We suggest that when an unusual radiological appearance like this is encountered, one should have a high index of suspicion for entities not typically on the list of differential diagnoses for spinal intradural lesions. Although asymptomatic ABCs can be observed, the typical treatment for symptomatic spinal column ABCs is complete surgical excision with preoperative embolization (14-17). Partial resections are associated with high recurrence rates (8), and both positive and negative outcomes have been reported for the use of radiation therapy as primary treatment in spinal ABCs (18-20). However, complications of
WORLD NEUROSURGERY - [-]: ---, MONTH 2015
radiation therapy in spinal ABCs include postradiation-induced malignancy (20-23). High rates of successful cure after complete excision and the benign nature of the disease limit the justification of primary or adjuvant radiation therapy for nonaggressive, operable disease (24, 25). Recurrent disease has been treated successfully with both complete surgical excision and radiation therapy (26). Preoperative arterial embolization of spinal ABCs can reduce intraoperative blood loss and may be therapeutic (15-17). Because our working diagnosis was a meningioma or a schwannoma (although it looked atypical for both), we did not attempt preoperative embolization. The intraoperative bleeding was easily controlled with Gelfoam and Cottonoid patties, and we retrospectively thought that embolization would not have significantly helped hemostasis. Our main intraoperative challenge was assessing the extent of the tumor’s margins and of our resection. At the end of the case we were concerned that the lesion had been incompletely resected, although this was not borne out on follow-up imaging. As it is the first reported extraosseous ABC involving the intradural extramedullary spinal canal, we believe that it is difficult to predict the long-term outcome. Given the high recurrence rate in other spinal ABCs, continued close follow-up is essential. Because we are suggesting that ABCs might now be considered in the differential diagnosis of intradural extramedullary spinal tumors, especially those appearing unusual on radiological imaging, further reports should consider both histological review and immunohistochemical analysis. ACKNOWLEDGMENTS The authors wish to acknowledge Dr. Edward Johnson for the description of the pathologic findings and accompanying photographic montage, prepared by Mr. Tom Turner, Division of Anatomical Pathology, Department of Laboratory Medicine and Pathology, University of Alberta. They also acknowledge Dr. Bernd Scheithauer, Mayo Medical Laboratories, Mayo Clinic, who reviewed the biopsy and confirmed the diagnosis of aneurysmal bone cyst.
www.WORLDNEUROSURGERY.org
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CASE REPORT MUTHANA SARTAWI ET AL.
SPINAL INTRADURAL ANEURYSMAL BONE CYST
Figure 3. Follow-up magnetic resonance imaging (MRI). At 20 months postoperatively, no recurrence seen on enhanced MRI whereas the signal change seen on T2weighted sequences persisted unchanged. (C), the line indicates the level from which the postoperative axial sections (DLF) are taken. T1-weighted sagittal (A); T1weighted post-gadolinium (GAD) (B); T2-weighted sagittal (C); Axial T1-weighted Turbo Spin Echo (D); T1-weighted post-GAD (E); T2-weighted (F).
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WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2015.02.012
CASE REPORT MUTHANA SARTAWI ET AL.
REFERENCES 1. Ajilogba KA, Kaur H, Duncan R, McFarlane JH, Watt AJ: Extraosseous aneurysmal bone cyst in a 12-year-old girl. Pediatr Radiol 35:1240-1242, 2005.
SPINAL INTRADURAL ANEURYSMAL BONE CYST
10. Feigenberg SJ, Marcus RB Jr, Zlotecki RA, Scarborough MT, Berrey BH, Enneking WF: Megavoltage radiotherapy for aneurysmal bone cysts. Int J Radiat Oncol Biol Phys 11:1243-1247, 2001.
2. Boriani S, De Iure F, Campanacci L, Gasbarrini A, Bandiera S, Biagini R, Bertoni F, Picci P: Aneurysmal bone cyst of the mobile spine: report on 41 cases. Spine 26:27-35, 2001.
11. Fellig Y, Oliveira AM, Margolin E, Gomori JM, Erickson-Johnson MR, Chou MM, Umansky F, Soffer D: Extraosseous aneurysmal bone cyst of cerebello-pontine angle with USP6 rearrangement. Acta Neuropathol 118:579-581, 2009.
3. Campanacci M, Capanna R, Picci P: Unicameral and aneurysmal bone cysts. Clin Orthop Relat Res 11:25-36, 1986.
12. Frassica FJ, Frassica DA, Wold LE, Beabout JW, Sim FH: Postradiation sarcoma of bone. Orthopedics 16:105-106, 1993.
4. Capanna R, Albisinni U, Picci P, Calderoni P, Campanacci M, Springfield D: Aneurysmal bone cyst of the spine. J Bone Joint Surg Am 67:527-531, 1985.
13. Gopalakrishnan CV, Rao BR, Nair S, Radhakrishnan VV, Kesavadas C: Intracranial intradural aneurysmal bone cyst: a unique case. Pediatr Neurosurg 45:317-320, 2009.
5. De Cristofaro R, Biagini R, Boriani S, Ricci S, Ruggieri P, Rossi G, Fabbri N, Roversi R: Selective arterial embolization in the treatment of aneurysmal bone cyst and angioma of bone. Skeletal Radiol 21:523-527, 1992.
14. Kamikonya N, Hishikawa Y, Kurisu K, Taniguchi M, Miura T: Aneurysmal bone cyst treated by high-energy, low-dose radiation therapy: a case report. Radiat Med 9:54-56, 1991.
6. De Kleuver M, van der Heul RO, Veraart BE: Aneurysmal bone cyst of the spine: 31 cases and the importance of the surgical approach. J Pediatr Orthop B 7:286-292, 1998. 7. DeRosa GP, Graziano GP, Scott J: Arterial embolization of aneurysmal bone cyst of the lumbar spine. A report of two cases. J Bone Joint Surg Am 72:777-780, 1990. 8. DiCaprio MR, Murphy MJ, Camp RL: Aneurysmal bone cyst of the spine with familial incidence. Spine (Phila Pa 1976) 25:1589-1592, 2000. 9. Dysart SH, Swengel RM, van Dam BE: Aneurysmal bone cyst of a thoracic vertebra. Treatment by selective arterial embolization and excision. Spine (Phila Pa 1976) 17:846-848, 1992.
15. Koci TM, Mehringer CM, Yamagata N, Chiang F: Aneurysmal bone cyst of the thoracic spine: evolution after particulate embolization. AJNR Am J Neuroradiol 16 (Suppl 4):857-860, 1995. 16. Mankin HJ, Hornicek FJ, Ortiz-Cruz E, Villafuerte J, Gebhardt MC: Aneurysmalbone cyst: a review of 150 patients. J Clin Oncol 23:6756-6762, 2005. 17. Mendenhall WM, Zlotecki RA, Gibbs CP, Reith JD, Scarborough MT, Mendenhall NP: Aneurysmal bone cyst. Am J Clin Oncol 29:311-315, 2006. 18. Oliveira AM, Perez-Atayde AR, Inwards CY, Medeiros F, Derr V, Hsi BL, Gebhardt MC, Rosenberg AE, Fletcher JA: USP6 and CDH11 oncogenes identify the neoplastic cell in primary aneurysmal bone cysts and are absent in so-called
WORLD NEUROSURGERY - [-]: ---, MONTH 2015
secondary aneurysmal bone cysts. Am J Pathol 165: 1773-1780, 2004. 19. Ozaki T, Halm H, Hillmann A, Blasius S, Winkelmann W: Aneurysmal bone cysts of the spine. Arch Orthop Trauma Surg 119:159-162, 1999. 20. Papagelopoulos PJ, Currier BL, Shaughnessy WJ, Sim FH, Ebsersold MJ, Bond JR, Unni KK: Aneurysmal bone cyst of the spine. Management and outcome. Spine 23:621-628, 1998. 21. Patel PJ, Demos TC, Lomasney LM, Rapp T: Your diagnosis? Aneurysmal bone cyst. Orthopedics 28: 428; 507-511, 2005. 22. Rao SR, Rao TR, Ovchinnikov N, McRae A, Rao AV: Unusual isolated ossification of falx cerberi: a case report. Neuroanatomy 6:54-55, 2007. 23. Tillman BP, Dahlin DC, Lipscomb PR, Stewart JR: Aneurysmal bone cyst: a clinicopathological study of 238 cases. Cancer 69:2921-2931, 1992. 24. Van Arsdale WW: II. Ossifying Haematoma. Ann Surg 18:8-17, 1893. 25. Vergel De Dios AM, Bond JR, Shives TC: McLeod RA: Aneurysmal bone cyst. A clinicopathologica study of 238 cases. Cancer 69:2921-2931, 1992. 26. Wang XL, Gielen JL, Salgado R, Delrue F, De Schepper AM: Soft tissue aneurysmal bone cyst. Skeletal Radiol 33:477-480, 2004.
Citation: World Neurosurg. (2015). http://dx.doi.org/10.1016/j.wneu.2015.02.012 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
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1.E5
Spinal Intradural Aneurysmal Bone Cyst: A Case Report Muthana Sartawi1, Ahmed Quateen2, Andrew Nataraj3, Robert Medairos4
Key words Aneurysmal bone cyst - Complete surgical resection - Extraosseous - Intradural - Vascular channels -
Abbreviations and Acronyms ABC: Aneurysmal bone Cyst MRI: Magnetic resonance imaging From the 1Department of Orthopedics, Dalhousie University, Nova Scotia, Canada; 2Mackenzie Health Sciences Centre and 3Department of Neurosurgery, University of Alberta, Alberta, Canada; and 4Rush Medical College, Chicago, Illinois, USA To whom correspondence should be addressed: Muthana Sartawi, BS.c., M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2015). http://dx.doi.org/10.1016/j.wneu.2015.02.012 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
INTRODUCTION Aneurysmal bone cyst (ABC) is an expanding osteolytic benign lesion accounting for approximately 1%e2% of all bone tumors (1). ABCs often occur within the first 2 decades of life, predominately located in the long bones and spine (2). Despite their benign nature, patients with spinal ABCs often present with pain and neurologic deficits caused by local obstruction and invasion into the surrounding tissue (2). To our knowledge, we report the first presentation of an extraosseous ABC involving the intradural extra-medullary spinal canal. CASE REPORT A 55-year-old healthy farm worker presented with 4 months of chest and back pain and 3 weeks of progressive leg pain and weakness. There was no numbness or
changes in bladder or bowel function. There were no constitutional symptoms and no significant medical history. On examination, he had grade 4/5 power bilaterally in his hip flexors. His power was otherwise intact, with normal reflexes and rectal tone. Sensory examination was normal except for diminished light touch sensation in the T7 dermatome. Gait analysis was prohibited by pain. Findings on magnetic resonance imaging (MRI) revealed an enhancing intradural extra-medullary lesion posterior to the T7 vertebral body, with significant spinal cord compression (Figure 1) but without involvement of the adjacent vertebral bodies. The lesion was of heterogeneous hyperintensity both on T1 and T2 imaging and also enhanced heterogeneously after gadolinium administration. We thought there either was hemorrhage or proteinaceous debris within the tumor. No fluid-fluid levels were identified. Dexamethasone was started, but the patient deteriorated over the subsequent 2 days to having grade 3/5 power in all lower limb myotomes. He was therefore taken for urgent surgery. A midline skin incision was made with exposure of the transverse processes and proximal ribs of T6 T8 on the right. Because of concern regarding tumor adherence to the anterior aspect of the spinal cord and visualization of such, in addition to a laminectomy, resection of the right transverse processes and posterior pedicle of T7 also was performed with disarticulation of the rib head. A ‘T’-shaped durotomy was made, with the horizontal aspect of this extending as far laterally as could be closed, given the bony exposure. The dentate ligament and left T7 root were divided. With the lateral bony structures removed, the tumor and lateral aspect of the spinal cord was visualized. The tumor was identified as a fleshy, purple mass, which was friable and non-adherent to the spinal cord. There
WORLD NEUROSURGERY - [-]: ---, MONTH 2015
was no obvious hemorrhage within it. Total excision was attempted, with tumor resection guided by intraoperative ultrasound and electrophysiological monitoring. It had indistinct margins, and we had difficulty assessing the extent of our resection ventromedially. There were several episodes of decreased motor evoked potentials, returning to baseline (which was impaired) after hypertensive therapy and time without tumor manipulation. Because the appearance of the tumor was somewhat unusual for either a meningioma or schwannoma, the ventrolateral extradural space and dura was also inspected after dural closure, without any abnormal appearing tissue found. Initially postoperatively, the patient’s pain improved and his power returned to a grade 4/5. He became ambulatory with a walker (similar to admission, but better than immediately pre-operatively). Histologically, it was a benign fibroosseous lesion with compact sheets of spindled cells and foci of newly formed bony trabecular lined by osteoblasts and telangectatic arrays of thin walled vascular channels (Figure 2). There were accompanying zones of recent hemorrhage in different stages of resorption. Clusters of multinucleated giant cells were scattered sporadically in the fibrous matrix. Mitotic figures were not observed. The pathologic diagnosis was an ABC. There were no areas of suspicion of concurrent neoplasm. The lesion was reviewed histologically at another institution (see Acknowledgements) for a second opinion, and corroborated our findings. At 6 months’ follow-up, the patient had minimal pain, and he was neurologically intact and fully ambulatory. At 54 months, he was neurologically intact without significant back pain and was able to participate in full activities. Imaging did not reveal any evidence of recurrent tumor. There was an increase in kyphosis of approximately 15 degrees over the first year of follow-up, but given the
www.WORLDNEUROSURGERY.org
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CASE REPORT MUTHANA SARTAWI ET AL.
SPINAL INTRADURAL ANEURYSMAL BONE CYST
Figure 1. Preoperative magnetic resonance imaging. Posterior to the T7 vertebral body, there is an area of heterogeneous increased T1 and T2 signal seen in intimate association with the anterior aspect of the spinal cord. This lesion demonstrates acute angles with the spinal cord superiorly and inferiorly. It exhibits dense peripheral enhancement, is slightly more centered to the left, and measures 2.0 cm (craniocaudad) by 0.7 cm (anterior-posterior) by 1.2 cm (transverse). The spinal cord at this level measures as little as 34 mm in thickness. However, no convincing cord edema is seen. In (C), the line indicates the level from which the preoperative axial sections (D G) are taken. T1-weighted sagittal (A), T1-weighted post-gadolinium (GAD); (B) T2-weighted sagittal (C); Axial T1-weighted turbo spin echo (TSE) (D) T1-weighted post-GAD; (E) T1-weighted fast spin echo (FSE) post-GAD; (F) T2-weighted (G).
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CASE REPORT MUTHANA SARTAWI ET AL.
Figure 2. A portion of tumor showing features of aneursymal bone cyst with foci of vascular spaces (v), radial arrays of osseous trabecular (o), and compact stoma (s). Medium magnification showing various sized vascular channels (v) in a fibrous matrix containing giant cells (arrows) and irregular osseous trabecular (o).
lack of symptoms, the patient was continued to be followed. There was no kyphosis beyond this at 54 months (Figure 3). DISCUSSION ABCs were historically described by Van Arsdale in 1893 as ossifying hematomas (3, 24). In 1942, the term “aneurysmal bone cyst” originated after 2 case reports of “peculiar blood-containing cysts of large size” (4). Our case is the first presentation of an extraosseous ABC involving the intradural extramedullary spinal canal.
SPINAL INTRADURAL ANEURYSMAL BONE CYST
The first reported intradural ABCs were intracranial, first in the cerebellopontine angle of a 25-year-old man (5), then along the sphenoid wing (6). There have been 13 other reports of extraosseous soft tissue ABCs (7). Our patient’s presentation was consistent with clinical features of other spinal ABCs, which include back pain, tenderness, and variable neurological deficits (8). Pathologic misdiagnosis for extraosseous ABCs include soft-tissue neoplasms such as extraskeletal osteosarcoma or ossifying fibromyxoid tumor, and nodular fasciitis with osteoclastic giant cells (9). Although our case did not have immunohistochemistry performed, we did have the histology reviewed at another institution (see Acknowledgements). Despite claims for potential markers to differentiate ABCs, no current system exists to confirm its diagnosis with immunohistochemical staining (10). There are several theories concerning the pathophysiology of intradural extraosseous ABCs primarily attributed to local hemodynamic disturbances. Postulated etiologies of ABCs include posttraumatic improper repair of subperiosteal hemorrhage, disturbance of bone vascularity, and hemorrhage into a preexisting lesion (11). Undiagnosed endocrine disorders or trauma have been speculated as potential causes of intradural-limited ossification (12). The radiological appearance in our patients was atypical for either schwannoma or meningioma. With varied hyperintensity on both T1 and T2 sequences, hemorrhage was suspected. However, there were no fluid-fluid levels that are pathognomonic for ABCs (13). We suggest that when an unusual radiological appearance like this is encountered, one should have a high index of suspicion for entities not typically on the list of differential diagnoses for spinal intradural lesions. Although asymptomatic ABCs can be observed, the typical treatment for symptomatic spinal column ABCs is complete surgical excision with preoperative embolization (14-17). Partial resections are associated with high recurrence rates (8), and both positive and negative outcomes have been reported for the use of radiation therapy as primary treatment in spinal ABCs (18-20). However, complications of
WORLD NEUROSURGERY - [-]: ---, MONTH 2015
radiation therapy in spinal ABCs include postradiation-induced malignancy (20-23). High rates of successful cure after complete excision and the benign nature of the disease limit the justification of primary or adjuvant radiation therapy for nonaggressive, operable disease (24, 25). Recurrent disease has been treated successfully with both complete surgical excision and radiation therapy (26). Preoperative arterial embolization of spinal ABCs can reduce intraoperative blood loss and may be therapeutic (15-17). Because our working diagnosis was a meningioma or a schwannoma (although it looked atypical for both), we did not attempt preoperative embolization. The intraoperative bleeding was easily controlled with Gelfoam and Cottonoid patties, and we retrospectively thought that embolization would not have significantly helped hemostasis. Our main intraoperative challenge was assessing the extent of the tumor’s margins and of our resection. At the end of the case we were concerned that the lesion had been incompletely resected, although this was not borne out on follow-up imaging. As it is the first reported extraosseous ABC involving the intradural extramedullary spinal canal, we believe that it is difficult to predict the long-term outcome. Given the high recurrence rate in other spinal ABCs, continued close follow-up is essential. Because we are suggesting that ABCs might now be considered in the differential diagnosis of intradural extramedullary spinal tumors, especially those appearing unusual on radiological imaging, further reports should consider both histological review and immunohistochemical analysis. ACKNOWLEDGMENTS The authors wish to acknowledge Dr. Edward Johnson for the description of the pathologic findings and accompanying photographic montage, prepared by Mr. Tom Turner, Division of Anatomical Pathology, Department of Laboratory Medicine and Pathology, University of Alberta. They also acknowledge Dr. Bernd Scheithauer, Mayo Medical Laboratories, Mayo Clinic, who reviewed the biopsy and confirmed the diagnosis of aneurysmal bone cyst.
www.WORLDNEUROSURGERY.org
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CASE REPORT MUTHANA SARTAWI ET AL.
SPINAL INTRADURAL ANEURYSMAL BONE CYST
Figure 3. Follow-up magnetic resonance imaging (MRI). At 20 months postoperatively, no recurrence seen on enhanced MRI whereas the signal change seen on T2weighted sequences persisted unchanged. (C), the line indicates the level from which the postoperative axial sections (DLF) are taken. T1-weighted sagittal (A); T1weighted post-gadolinium (GAD) (B); T2-weighted sagittal (C); Axial T1-weighted Turbo Spin Echo (D); T1-weighted post-GAD (E); T2-weighted (F).
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WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2015.02.012
CASE REPORT MUTHANA SARTAWI ET AL.
REFERENCES 1. Ajilogba KA, Kaur H, Duncan R, McFarlane JH, Watt AJ: Extraosseous aneurysmal bone cyst in a 12-year-old girl. Pediatr Radiol 35:1240-1242, 2005.
SPINAL INTRADURAL ANEURYSMAL BONE CYST
10. Feigenberg SJ, Marcus RB Jr, Zlotecki RA, Scarborough MT, Berrey BH, Enneking WF: Megavoltage radiotherapy for aneurysmal bone cysts. Int J Radiat Oncol Biol Phys 11:1243-1247, 2001.
2. Boriani S, De Iure F, Campanacci L, Gasbarrini A, Bandiera S, Biagini R, Bertoni F, Picci P: Aneurysmal bone cyst of the mobile spine: report on 41 cases. Spine 26:27-35, 2001.
11. Fellig Y, Oliveira AM, Margolin E, Gomori JM, Erickson-Johnson MR, Chou MM, Umansky F, Soffer D: Extraosseous aneurysmal bone cyst of cerebello-pontine angle with USP6 rearrangement. Acta Neuropathol 118:579-581, 2009.
3. Campanacci M, Capanna R, Picci P: Unicameral and aneurysmal bone cysts. Clin Orthop Relat Res 11:25-36, 1986.
12. Frassica FJ, Frassica DA, Wold LE, Beabout JW, Sim FH: Postradiation sarcoma of bone. Orthopedics 16:105-106, 1993.
4. Capanna R, Albisinni U, Picci P, Calderoni P, Campanacci M, Springfield D: Aneurysmal bone cyst of the spine. J Bone Joint Surg Am 67:527-531, 1985.
13. Gopalakrishnan CV, Rao BR, Nair S, Radhakrishnan VV, Kesavadas C: Intracranial intradural aneurysmal bone cyst: a unique case. Pediatr Neurosurg 45:317-320, 2009.
5. De Cristofaro R, Biagini R, Boriani S, Ricci S, Ruggieri P, Rossi G, Fabbri N, Roversi R: Selective arterial embolization in the treatment of aneurysmal bone cyst and angioma of bone. Skeletal Radiol 21:523-527, 1992.
14. Kamikonya N, Hishikawa Y, Kurisu K, Taniguchi M, Miura T: Aneurysmal bone cyst treated by high-energy, low-dose radiation therapy: a case report. Radiat Med 9:54-56, 1991.
6. De Kleuver M, van der Heul RO, Veraart BE: Aneurysmal bone cyst of the spine: 31 cases and the importance of the surgical approach. J Pediatr Orthop B 7:286-292, 1998. 7. DeRosa GP, Graziano GP, Scott J: Arterial embolization of aneurysmal bone cyst of the lumbar spine. A report of two cases. J Bone Joint Surg Am 72:777-780, 1990. 8. DiCaprio MR, Murphy MJ, Camp RL: Aneurysmal bone cyst of the spine with familial incidence. Spine (Phila Pa 1976) 25:1589-1592, 2000. 9. Dysart SH, Swengel RM, van Dam BE: Aneurysmal bone cyst of a thoracic vertebra. Treatment by selective arterial embolization and excision. Spine (Phila Pa 1976) 17:846-848, 1992.
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