ACTA NEUROCHIRURGICA
Acta Neurochirurgica 39, 101-- 113 (1977)
9 by Springer-Verlag 1977
Radioisotopic Centre and Neurosurgical Clinic Faculty of Medicine, Plovdiv, Bulgaria
Aneurysmal Bone Cyst of the Spine By M. Karparov
a n d D. K i t o v
With 9 Figures
Summary Long term follow up of three patients with aneurysmal bone cysts has allowed us to draw attention to features which facilitate diagnosis and determine adequate treatment. The lesion occurs usually under the age of twenty with a slight female predominance. Treatment consists in complete local excision. Failing this, curettage should be carried out, and this gives good results. The effectiveness of radiotherapy cannot be assessed from our series, but in our opinion it may not be necessary in every case and shoud be applied judiciously, as postradiation sarcomas have been reported. Special attention must be paid to the tendency for spontaneous regression and cure after incomplete removal, particularly in recurrent cases, with a view to avoiding more aggressive treatment than is necessary. Multilocation (vertebra and distant bone), endothelial proliferation, and obliteration of the lumen of the small blood vessels support the view that this is a vascular lesion.
Aneurysmal bone cyst was first described as a distinct clinical and pathological entity by Jaffe and Lichtenstein 11 in 1942. While the radiological picture of a blow-out and the cystic nature of the lesion are quite characteristic in the long bones, spinal lesions present some peculiarities which deserve special attention. The long term follow up and clinical control of three patients with aneurysmal bone cysts have stimulated us to report on our experience in the diagnosis and treatment of this benign lesion which can cause, especially when located in the vertebral column, dramatic symptoms.
Case Reports Case 1. A girl aged fourteen was admitted in January 1958 with complaints of pain in the back, tingling of both lower limbs for three months, and progressive paraparesis of ten days' duration.
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On examination there was a slight prominence and tenderness on the right side in the region of the sixth and seventh thoracic vertebrae. Neurological examination revealed complete spastic paraplegia, with sensory level at the xiphoid process. Laboratory studies were normal. Radiological examination revealed absence of the right pedicle of the seventh thoracic vertebra ('one-eyed vertebra') with partial destruction of the right transverse process (Fig. 1). Laminectomy of the sixth and seventh thoracic vertebrae was performed with
Fig. 1. Absence of the right pedicle of the seventh thoracic vertebra--"one eyed vertebra" (arrow) complete removal of a tumour mass, 5 to 7 cm in size, separated from the surrounding tissues by a thin shell of bone and full of vascular reddish tissue. The process had destroyed almost completely the right transverse process of D 7 and had extended into the vertebral body, forming a small cavity in it. Microscopy revealed giant cell turnout (osteoclastoma). The patient was given a postoperative course of X-ray therapy--4,000 rads (skin)--through two paravertebral ports. She made a complete neurological recovery within three weeks of the operation and before the conclusion of the X-ray therapy. She was asymptomatic at the last examination, in good health, seventeen years after treatment, and there is no sign of recurrence. We have since reviewed the histology in this case. Examination of the tissue
Aneurysmal Bone Cyst of the Spine
103
sections indicate clearly that it was an aneurysmai bone cyst. The most striking feature on microscopic examination is the presence of numerous channels and spaces, filled with erythrocytes and bordered by supporting connective tissue which often shows evidence of multinucleated giant cells and new bone formation (Fig. 2). Retrospective analysis of the roentgenograms taken every month in the postoperative period has shown an interesting development. On the roentgenogram performed two months after X-ray therapy, small cystic changes were revealed at the level of the right transverse process of the seventh thoracic vertebra, as well as in the head of the seventh rib on the right (Fig. 3). These features cannot
Fig. 2 be seen in the roentgenograms taken before operation (Fig. 1). They developed after X-ray therapy and disappeared in the ensuing two months. Case 2. A girl aged fourteen stated on admission in June 1969 that for about a year she had noticed a dull pain in the lower back, mainly on the right, and after standing for more than a short time. Clinical examination revealed a stiff lumbar spine with scoliosis convex to the left. There was tenderness in the region of the fifth lumbar vertebra. A lumbar route myelogram suggested an extradural lesion. Radiological examination showed partial destruction of the right pedicle of the fourth lumbar vertebra (Fig. 4). At operation the right lamina of L 4 was found to be replaced by spongy reddish vascular tissue, involving the adjacent muscles. Laminectomy with incomplete removal of the abnormal tissue was performed. The microscopic appearance was first thought to be that of osteoclastoma. Before undertaking any further treatment we directed our attention to the possibility that the process was an aneurysmal bone cyst. Review of the histology confirmed this latter diagnosis. There were vascular spaces of varying size, blood-tinged or sometimes without fluid, lined by thin sheets of flattened fibrocytes (Fig. 5). There were
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also numerous giant ceils with several nuclei and evidence of osteoid tissue in some parts of the solid portions. The surrounding muscles demonstrated atrophy and a tendency towards sclerosis. A significant number of the vessels showed extensive endothelial proliferation, causing luminal obliteration (Fig. 6). It was difficult to relate these vascular changes to a neoplastic process, the impression being predominantingly of changes resulting from an allergic-inflammatory condition.
Fig. 3. Small cystic lesions in the region of the right transverse process of the seventh thoracic vertebra and in the head of the seventh rib (arrow). Laminectomy of the sixth and seventh thoracic vertebrae Bearing in mind that X-ray therapy did not appear to contribute to the abatement of the neurological findings in our first case, we decided not to give radiotherapy but to submit this second case to close observation during the first months after the operation. The patient made a complete neurological recovery in spite of the incomplete surgical removal. She is in good health after six years. In May 1972 the girl presented with complaints of pain and mild swelling in the right leg for about one month. On examination there was slight prominence in the region under the knee. The roentgenograms demonstrated an eccentric oseolytic metaphyseal cystic lesion in the upper third of the right tibia (Fig. 7). No other abnormal finding was found on clinical examination. Curettage was carried out. The small cyst contained nothing but blood. Sections of small pieces
Aneurysmal Bone Cyst of the Spine
105
of the cortex showed the picture of an aneurysmal bone cyst. At follow up examinations the patient had no symptoms. At the last examination in January 1976 the control roentgenograms showed a second cystic lesion, near the first in the right tibia (Fig. 8). There was no swelling or pain in the leg. We decided not to operate but to observe progress during the ensuing months. Case 3. A girl aged seventeen presented in April 1968 with pain, tingling and weakness of the right arm. Neurological examination revealed signs of nerve root irritation at the level of the seventh cervical vertebra.
Fig. 4. Particai destruction of the right pedicle of the fourth lumbar vertebra (arrow). Scoliosis of the lumbar spine convex to the left The results of the laboratory studies were normal. Roentgenograms and tomograms (Fig. 9) disclosed small cystic lesions in the right half of the seventh cervical vertebra. The patient rejected surgical interference and radiotherapy. She was treated symptomatically. Symptoms disappeared within eight months. She married in a foreign country. Information from her parents has shown that the patient, eight years after the first examination, is in good health, has had a child, and has become a hospital nurse.
Discussion The l i t e r a t u r e o n a n e u r y s m a l b o n e cyst has become quite extensive d u r i n g recent years. D o m i n o k a n d K n o c h 9 (1971) h a v e gathered
106
M. Karparov and D. Kitov:
from the literature 337 cases of aneurysmal bone cysts, 68 in the vertebrae and 11 in the sacrococcygeal region. Clinical features. Aneurysmal cyst occurs almost exclusively in children and young adolescents under the age of twenty 6, v, 9, ~3, iv, ~ In the extensive material of Tillman et aI..~6, eighty percent of the patients were under twenty. The vertebral column is a frequent site of aneurysmal bone cyst s, x5 16, 24, ~6 The vertebral
Fig, 5 lesion produces pain, often radicular, associated with muscle spasm and varying degrees of paralysis of the limbs 16, 19, 22, ~ Our first patient was paraplegic before operation. Palpable local swelling or tenderness may be met with. In our series the three patients were female. In other series 4, 6, 18, 16, ~l the sex incidence has been more or less equal, but slight female predominance has been reported as well 5, 9, ~s, 26 Roentgenology. In the spine the X-ray findings are quite typical in some instances. The dorsal processes are more commonly involved than the bodies. The lesion begins eccentrically in the body, in a pedicle, or a lamina. It is important to note that the process may affect two or more adjacent vertebrae, or a vertebra and adjacent rib (case 1). Multiple involvement of vertebrae was observed in 7 of the 15 cases reported by Tillman et al. 26 with four adjacent vertebrae affected in one patient. This extension from a bone to the one adjacent or from one part of a vertebra to a distant part of the same vertebra proved to be an useful roentgenologic sign. The trabeculated cystic appearance, when present, supports the diagnosis 26 (case 1, case 3). Larger lesions showing expanded osteolytic
Aneurysmal Bone Cyst of the Spine
107
Fig. 6
Fig. 7. Eccentric osteolytic cystic lesion in the upper third of the right tibia (May 1972). AP and lateral view
108
M. Karparov and D. Kitov:
areas with little or no internal structure are mistaken for a malignant process. A thin shell of bone often remains but it is not always visualized on the roentgenograms (case 1). Multiple involvement has been described in neighbouring bones or regions (Tillmann et al. e6--talus and medial malleolus of the tibial; Palma and Venturini e~ and sacroiliac joint; Besse
Fig. 8. The control roentgenograms (January 1976) have shown a second more expanded cystic lesion, in close proximity to the earlier one, curetted four years previously et al. 3--tibia, fibula, femoral condyles; Lichtenstein l~--distal tibial
epiphysis and fibula, tarsus, and metatarsus). In this respect our patient, reported as case 2, merits special attention. We have not found in the literature a description of multiple involvement including the spine and a distant bone in our case the tibia. We believe that this is an important finding, supporting the diagnosis of aneurysmal bone cyst and indicating the need for X-ray skeletal survey in every case in which the spine is involved. Myelography is of great value (case 2). The presence of an extradural defect on the myelogram should encourage prompt treatment.
Aneurysmal Bone Cyst of the Spine
109
Pathology. The microscopic appearances have been extensively reviewed, and no detailed description will be attempted here. The lesion is characterized by numerous small or large spaces, filled with blood or blood-tinged fluid and bordered by multinucleated giant cells and reactive stromal fibroblasts. The walls of the spaces lack elastic tissue and muscle and, when thicker, these septa often contain fibrous tissue, immature bony trabeculae, and osteoid tissue.
Fig. 9. Tomogram. Three small cystic lesions in the region of the right pedicle of the seventh cervical vertebra
Pathogenesis. The most favoured view of the origin of the aneurysmal bone cyst is that of a vascular disturbance in the form of a sudden venous occlusion or the development of an arteriovenous shunt 6 ,0. t< ,5 There were some features in our second patient (case 2) which seem to support the vascular nature of the lesion. There is firstly the conspicuous endothelial proliferation in numerous blood vessels with subsequent obliteration of lumen (Fig. 6). On the other hand the multilocation of the process in different part of the skeleton accords more with vascular changes occurring usually in the newly formed most vascular parts of the immature bones. Kagan
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M. Karparov and D. Kitov:
and Klimova 12 particularly emphasize the very frequent coincidence of the lesion with the anatomical disposition of nutrient arteries. What causes these vascular disturbances is unknown. T r e a t m e n t . In cases with vertebral location complete local excision, when possible, is the treatment of choice. Failing this, careful curettage should be carried out. Some authors 3, 14, 16 claim that curettage alone is sufficient for cure. According to Jaffe 11, Lichtenstein 14, Besse et al. 3, the patient may be cured if curettage is incomplete, as in our second case. The surgical treatment of the vertebral cyst may become difficult because of extensive haemorrhage or inaccessibility. R a d i o t h e r a p y . From the literature it appears that the reasons for including radiotherapy in the treatment are based on several concepts. According to Taylor 25 and Carlson 5 radiotherapy should be reserved for surgical failure or for situations where surgical access is difficult or impossible. Others 7, 8, 26, 27 say irradiation may be used as an adjunct to surgical treatment. Initial radiation therapy was given by Biesecker et al. 4. Advocates of radiation therapy as primary treatment of choice are Nobler et al. is, and Kubicz la, who have reported excellent results. The recommended doses are between 1,200 and 3,000 rads 4, s, as, 2i, 27 Most authors ~, 16, ~7, ,9, 22, e~ consider that radiotherapy may not be necessary and should be used only exceptionally. Possible damage to the epiphyseal plate with subsequent interference with growth should preclude its use in the majority of cases. Especially in vertebral cases damage to the spinal cord and sterilisation are risks which must be considered. As sarcomas have been reported 8, 14, 21, 2~ in irradiated sites, radiation therapy should be used judiciously in treating this benign lesion. This is not the only reason for the usual note of caution in regard to radiotherapy. As spontaneous healing of an aneurysmal bone cyst may occur 22, 24 it appears that there are no absolute indications for its use. On the other hand there are observations which demonstrate the ineffectivenes of radiotherapy. Kagan and Klimova le reported a case treated first as reticulosarcoma of the femur with 6~ (7,500 rads tumour dose) without improvement. The right diagnosis of aneurysmal bone cyst was established after surgical removal, performed two months later because of the persistence of complaints and the roentgenologic findings. In our first patient (case 1), despite radiotherapy, there was a recurrence in the form of asymptomatic small cystic lesions. This was one of the reasons for our decision not to apply radiation therapy in the second patient (Case 2), in spite of incomplete removal. Spontaneous cure and recurrence. The tendency of the process
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111
to heal spontaneously is reported by several authors 1, s, la, 19, 22, 2,~ Sherman and Soong 24 have noted spontaneous calcification of an aneurysmai bone cyst of the third lumbar vertebra without any treatment. Biopsy was not performed. Rigault et al. 22 have reported a case of aneurysmal bone cyst of the second cervical vertebra without histology, but with a typical X-ray picture, cured without surgery or radiotherapy, by nineteen months of immobilization. Our third patient resembles these cases. The favourable response of the process to even incomplete removal has been pointed out a, s, 14, 19, 27 In our second case this was the other reason which made us wait and see the result of the surgery and not proceed to postoperative radiotherapy. The spinal lesion shows less tendency to relapse. Detection of residual cysts in the postoperative period, or appearance of new cysts on the control roentgenograms, are not a reliable indication that recurrence will follow and that operative interference is needed. As long as these relatively small cysts do not cause clinical manifestations our attitude should be expective, keeping the patient under close control. We must not neglect the fact pointed out by Tillman et al. 20 that the frequency of recurrence decreases with age and depends on the location of the process. Differential diagnosis. In spite of the numerous lesions that resemble aneurysmal bone cyst, the correct diagnosis can be made with confidence, especially in cases with vertebral location where the number of diagnostic possibilities seems to be limited. Most of the cases with vertebral aneurysmal bone cyst have been first diagnosed histologically as giant cell tumours. This lesion may contain in some instances spaces filled with blood or serous fluid, but the cellular zones are devoid of fibrous or bone tissue ~, 7, 8, 26 Dabska and Buraczewski s pointed out that giant cell tumour does not produce osteoid tissue unless irradiated. The presence of small multinuclear giant cells seems to be responsible for the frequent confusion of aneurysmal bone cyst with giant cell turnout. In aneurysmal bone cyst the differentiating feature is the presence of islets of osteoid and new bone which appear to have a reparative function v, 14 It is important to note that giant cell tumours are extremely rare in the spine above the sacrum 9, 16, ~9, 26 and before the age of twenty. Paillas et al. 19 draw attention to the fact that the osteolytic process is usually much more expansive in the aneurysmal bone cyst than in the giant cell turnout. In any case the X-ray examination, the clinical picture, and the histology should all be considered together carefully for diagnosis to be made and treatment planned,
112
M. Karparov and D. Kitov: References
1. Barnes, R., Aneurysmal bone cyst. J. Bone Jt Surg. 38-B (1956), 301--311. 2. Beeler, J. W., Helmann, C. H., Campell, J. A., AneurysmaI bone cyst of spine. JAMA 163 (1957), 914--918. 3. Besse, B. E., Dahlin, D. C., Pugh, D. G., Ghormley, R. K., Aneurysmal bone cyst, additional considerations. Clin. Orthop. 7 (1956), 93--98. 4. Biescker, J. L., Marcove, R. C., Huvos, A. G., Mike, V., Aneurysmal bone cysts. Cancer 26 (1970), 618--625. 5. Carlson, D. H., Wilkinson, R. H., Bhakkaviziam, A., Aneurysmal bone cysts in children. Amer. J. Roentgenol. 116 (1972), 644--650. 6. Clough, J. R., Price, C. H. G., Aneurysmal bone cysts. J. Bone Jt. Surg. 50-B, (1968), 116--127. 7. Crabbe, W. A., Aneurysmal bone cyst and its atypical features. Guy's Hosp. Rep. 111 (1962), 347--354. 8. Dabska, M., Buraczewski, J., Aneurysmal bone cyst. Pathology, Clinical course and radiologic appearances. Cancer 23 (1969), 371--389. 9. Dominok, G. W., Knoch, H. G., Knochengeschwiilste und geschwulst~.hnliehe Knochenerkrankungen, pp. 289--302. Jena: VEB G. Fischer. 1971. 10. Donaldson, W. F., Aneurysmal bone cyst. J. Bone Jt. Surg. 44-A (1962), 25--40. 11. Jaffa, H. J., Lichtenstein, L., Solitary unicameral bone cyst with lymphasis on roentgen picture, pathologic appearance and pathogenesis. Arch. Surg. 44 (1942), 1004--1025. 12. Kagan, E. M., Klimova, M. K., Aneurysmal bone cysts. Vesm. Roentgenol. and Radiol. (Moscow) 2 (1965), 3--9. 13. Kubicz, S., Aspect radiologique du kyste osseux an~vrysmal chez l'enfant. Ann. Radiol. 13 (1970), 211--218. 14. Lichtenstein, L., Aneurysmal bone cyst, further observations. Cancer 6 (1953), 1228--1237. I5. Lichtenstein, L., Aneurysmal bone cyst: Observations on fifty cases. J. Bone Jr. Surg. 39-A (1957), 873--882. 16. McCarty, C. S., Dahlin, D. C., Doyle, J. B., Lipscomb, P. R., Pugh, D. G., Aneurysmal bone cyst of the neural axis. J. Neurosurg. I8 (1961), 671--677. 17. Mastragostino, S., Candle, G., Aneurysmal bone cysts. Lo Scalpello (1973), 95--114. 18. Nobler, M. P., Higinbotham, H. L., Phillips, R. F., Irradiation superior to surgery in an analysis of 33 cases. Radiology 90 (1960), 1185--1192. 19. Paillas, J. E., Serratrice, G., Legr~, J., Les tumeurs primitifs du rachis, pp. 65--82. Paris: Masson. 1963. 20. Palma, V., Venturinni, G., Su di un caso di cisn aneurismatica ossea a duplice localizzazione. Minerva Ortop. 10 (1959), 739--742. 21. Prakash, B., Banerji, A. K., Tandon, P. M., Aneurysmal bone cyst of the spine. J. Neurol. Neurosurg. Psychiatr. 36 (1973), 112--117. 22. Rigault, P., Beneux, J., Desvignes, P., Le kyste anevrysmal des os chez l'enfant. Ann. P~diat. 19 (1972), 223--234. 23. Sabanas, A. O., Dahlin, D. C., Childs, D. C., Dins, J. C., Postradiation sarcoma of bone. Cancer 9 (1956), 528--542. 24. Sherman, R. S., Soong, K. J., Aneurysmal bone cyst: Its Roentgen Diagnosis. Radiology 68 (1957), 54--64. 25. Taylor, F. W., Aneurysmal bone cyst. J. Bone Jr. Surg. 38-B (1956), 293--300.
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26. Tillman, B. P., Dahlin, D. C., Lipscomb, P. R., Stewart, J. R., Aneurysmal bone cyst: an analysis of ninety five cases. Mayo Clin. Proc. 43 (1968), 478--495. 27. Tzivkin, M. V., Panichev, A. F., Vahrushev, E. H., Comparative evaluation of the therapeutic methods by aneurysmal bone cysts of the spine. Vestn. Khirur. Grecova (Moscow), 112 (1974), 64--68. 28. Verbiest, H., Giant cell tumors and aneurysmal bone cyst of spine. J. Bone Jt. Surg. 47-B (1965), 699--713. Authors' address: Assis. Prof. Dr. M. Karparov, Radioisotopic Centre, and Prof. Dr. D. Kitov, Neurosurgical Clinic, Faculty of Medicine "I.P. Pavlov", Plovdiv, Bulgaria.
Acta Neurochirurgica, Vol. 89, Fasc. 1--2
8
Acta Neurochirurgica 39, 101-- 113 (1977)
9 by Springer-Verlag 1977
Radioisotopic Centre and Neurosurgical Clinic Faculty of Medicine, Plovdiv, Bulgaria
Aneurysmal Bone Cyst of the Spine By M. Karparov
a n d D. K i t o v
With 9 Figures
Summary Long term follow up of three patients with aneurysmal bone cysts has allowed us to draw attention to features which facilitate diagnosis and determine adequate treatment. The lesion occurs usually under the age of twenty with a slight female predominance. Treatment consists in complete local excision. Failing this, curettage should be carried out, and this gives good results. The effectiveness of radiotherapy cannot be assessed from our series, but in our opinion it may not be necessary in every case and shoud be applied judiciously, as postradiation sarcomas have been reported. Special attention must be paid to the tendency for spontaneous regression and cure after incomplete removal, particularly in recurrent cases, with a view to avoiding more aggressive treatment than is necessary. Multilocation (vertebra and distant bone), endothelial proliferation, and obliteration of the lumen of the small blood vessels support the view that this is a vascular lesion.
Aneurysmal bone cyst was first described as a distinct clinical and pathological entity by Jaffe and Lichtenstein 11 in 1942. While the radiological picture of a blow-out and the cystic nature of the lesion are quite characteristic in the long bones, spinal lesions present some peculiarities which deserve special attention. The long term follow up and clinical control of three patients with aneurysmal bone cysts have stimulated us to report on our experience in the diagnosis and treatment of this benign lesion which can cause, especially when located in the vertebral column, dramatic symptoms.
Case Reports Case 1. A girl aged fourteen was admitted in January 1958 with complaints of pain in the back, tingling of both lower limbs for three months, and progressive paraparesis of ten days' duration.
102
M. Karparov and D. Kitov:
On examination there was a slight prominence and tenderness on the right side in the region of the sixth and seventh thoracic vertebrae. Neurological examination revealed complete spastic paraplegia, with sensory level at the xiphoid process. Laboratory studies were normal. Radiological examination revealed absence of the right pedicle of the seventh thoracic vertebra ('one-eyed vertebra') with partial destruction of the right transverse process (Fig. 1). Laminectomy of the sixth and seventh thoracic vertebrae was performed with
Fig. 1. Absence of the right pedicle of the seventh thoracic vertebra--"one eyed vertebra" (arrow) complete removal of a tumour mass, 5 to 7 cm in size, separated from the surrounding tissues by a thin shell of bone and full of vascular reddish tissue. The process had destroyed almost completely the right transverse process of D 7 and had extended into the vertebral body, forming a small cavity in it. Microscopy revealed giant cell turnout (osteoclastoma). The patient was given a postoperative course of X-ray therapy--4,000 rads (skin)--through two paravertebral ports. She made a complete neurological recovery within three weeks of the operation and before the conclusion of the X-ray therapy. She was asymptomatic at the last examination, in good health, seventeen years after treatment, and there is no sign of recurrence. We have since reviewed the histology in this case. Examination of the tissue
Aneurysmal Bone Cyst of the Spine
103
sections indicate clearly that it was an aneurysmai bone cyst. The most striking feature on microscopic examination is the presence of numerous channels and spaces, filled with erythrocytes and bordered by supporting connective tissue which often shows evidence of multinucleated giant cells and new bone formation (Fig. 2). Retrospective analysis of the roentgenograms taken every month in the postoperative period has shown an interesting development. On the roentgenogram performed two months after X-ray therapy, small cystic changes were revealed at the level of the right transverse process of the seventh thoracic vertebra, as well as in the head of the seventh rib on the right (Fig. 3). These features cannot
Fig. 2 be seen in the roentgenograms taken before operation (Fig. 1). They developed after X-ray therapy and disappeared in the ensuing two months. Case 2. A girl aged fourteen stated on admission in June 1969 that for about a year she had noticed a dull pain in the lower back, mainly on the right, and after standing for more than a short time. Clinical examination revealed a stiff lumbar spine with scoliosis convex to the left. There was tenderness in the region of the fifth lumbar vertebra. A lumbar route myelogram suggested an extradural lesion. Radiological examination showed partial destruction of the right pedicle of the fourth lumbar vertebra (Fig. 4). At operation the right lamina of L 4 was found to be replaced by spongy reddish vascular tissue, involving the adjacent muscles. Laminectomy with incomplete removal of the abnormal tissue was performed. The microscopic appearance was first thought to be that of osteoclastoma. Before undertaking any further treatment we directed our attention to the possibility that the process was an aneurysmal bone cyst. Review of the histology confirmed this latter diagnosis. There were vascular spaces of varying size, blood-tinged or sometimes without fluid, lined by thin sheets of flattened fibrocytes (Fig. 5). There were
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also numerous giant ceils with several nuclei and evidence of osteoid tissue in some parts of the solid portions. The surrounding muscles demonstrated atrophy and a tendency towards sclerosis. A significant number of the vessels showed extensive endothelial proliferation, causing luminal obliteration (Fig. 6). It was difficult to relate these vascular changes to a neoplastic process, the impression being predominantingly of changes resulting from an allergic-inflammatory condition.
Fig. 3. Small cystic lesions in the region of the right transverse process of the seventh thoracic vertebra and in the head of the seventh rib (arrow). Laminectomy of the sixth and seventh thoracic vertebrae Bearing in mind that X-ray therapy did not appear to contribute to the abatement of the neurological findings in our first case, we decided not to give radiotherapy but to submit this second case to close observation during the first months after the operation. The patient made a complete neurological recovery in spite of the incomplete surgical removal. She is in good health after six years. In May 1972 the girl presented with complaints of pain and mild swelling in the right leg for about one month. On examination there was slight prominence in the region under the knee. The roentgenograms demonstrated an eccentric oseolytic metaphyseal cystic lesion in the upper third of the right tibia (Fig. 7). No other abnormal finding was found on clinical examination. Curettage was carried out. The small cyst contained nothing but blood. Sections of small pieces
Aneurysmal Bone Cyst of the Spine
105
of the cortex showed the picture of an aneurysmal bone cyst. At follow up examinations the patient had no symptoms. At the last examination in January 1976 the control roentgenograms showed a second cystic lesion, near the first in the right tibia (Fig. 8). There was no swelling or pain in the leg. We decided not to operate but to observe progress during the ensuing months. Case 3. A girl aged seventeen presented in April 1968 with pain, tingling and weakness of the right arm. Neurological examination revealed signs of nerve root irritation at the level of the seventh cervical vertebra.
Fig. 4. Particai destruction of the right pedicle of the fourth lumbar vertebra (arrow). Scoliosis of the lumbar spine convex to the left The results of the laboratory studies were normal. Roentgenograms and tomograms (Fig. 9) disclosed small cystic lesions in the right half of the seventh cervical vertebra. The patient rejected surgical interference and radiotherapy. She was treated symptomatically. Symptoms disappeared within eight months. She married in a foreign country. Information from her parents has shown that the patient, eight years after the first examination, is in good health, has had a child, and has become a hospital nurse.
Discussion The l i t e r a t u r e o n a n e u r y s m a l b o n e cyst has become quite extensive d u r i n g recent years. D o m i n o k a n d K n o c h 9 (1971) h a v e gathered
106
M. Karparov and D. Kitov:
from the literature 337 cases of aneurysmal bone cysts, 68 in the vertebrae and 11 in the sacrococcygeal region. Clinical features. Aneurysmal cyst occurs almost exclusively in children and young adolescents under the age of twenty 6, v, 9, ~3, iv, ~ In the extensive material of Tillman et aI..~6, eighty percent of the patients were under twenty. The vertebral column is a frequent site of aneurysmal bone cyst s, x5 16, 24, ~6 The vertebral
Fig, 5 lesion produces pain, often radicular, associated with muscle spasm and varying degrees of paralysis of the limbs 16, 19, 22, ~ Our first patient was paraplegic before operation. Palpable local swelling or tenderness may be met with. In our series the three patients were female. In other series 4, 6, 18, 16, ~l the sex incidence has been more or less equal, but slight female predominance has been reported as well 5, 9, ~s, 26 Roentgenology. In the spine the X-ray findings are quite typical in some instances. The dorsal processes are more commonly involved than the bodies. The lesion begins eccentrically in the body, in a pedicle, or a lamina. It is important to note that the process may affect two or more adjacent vertebrae, or a vertebra and adjacent rib (case 1). Multiple involvement of vertebrae was observed in 7 of the 15 cases reported by Tillman et al. 26 with four adjacent vertebrae affected in one patient. This extension from a bone to the one adjacent or from one part of a vertebra to a distant part of the same vertebra proved to be an useful roentgenologic sign. The trabeculated cystic appearance, when present, supports the diagnosis 26 (case 1, case 3). Larger lesions showing expanded osteolytic
Aneurysmal Bone Cyst of the Spine
107
Fig. 6
Fig. 7. Eccentric osteolytic cystic lesion in the upper third of the right tibia (May 1972). AP and lateral view
108
M. Karparov and D. Kitov:
areas with little or no internal structure are mistaken for a malignant process. A thin shell of bone often remains but it is not always visualized on the roentgenograms (case 1). Multiple involvement has been described in neighbouring bones or regions (Tillmann et al. e6--talus and medial malleolus of the tibial; Palma and Venturini e~ and sacroiliac joint; Besse
Fig. 8. The control roentgenograms (January 1976) have shown a second more expanded cystic lesion, in close proximity to the earlier one, curetted four years previously et al. 3--tibia, fibula, femoral condyles; Lichtenstein l~--distal tibial
epiphysis and fibula, tarsus, and metatarsus). In this respect our patient, reported as case 2, merits special attention. We have not found in the literature a description of multiple involvement including the spine and a distant bone in our case the tibia. We believe that this is an important finding, supporting the diagnosis of aneurysmal bone cyst and indicating the need for X-ray skeletal survey in every case in which the spine is involved. Myelography is of great value (case 2). The presence of an extradural defect on the myelogram should encourage prompt treatment.
Aneurysmal Bone Cyst of the Spine
109
Pathology. The microscopic appearances have been extensively reviewed, and no detailed description will be attempted here. The lesion is characterized by numerous small or large spaces, filled with blood or blood-tinged fluid and bordered by multinucleated giant cells and reactive stromal fibroblasts. The walls of the spaces lack elastic tissue and muscle and, when thicker, these septa often contain fibrous tissue, immature bony trabeculae, and osteoid tissue.
Fig. 9. Tomogram. Three small cystic lesions in the region of the right pedicle of the seventh cervical vertebra
Pathogenesis. The most favoured view of the origin of the aneurysmal bone cyst is that of a vascular disturbance in the form of a sudden venous occlusion or the development of an arteriovenous shunt 6 ,0. t< ,5 There were some features in our second patient (case 2) which seem to support the vascular nature of the lesion. There is firstly the conspicuous endothelial proliferation in numerous blood vessels with subsequent obliteration of lumen (Fig. 6). On the other hand the multilocation of the process in different part of the skeleton accords more with vascular changes occurring usually in the newly formed most vascular parts of the immature bones. Kagan
110
M. Karparov and D. Kitov:
and Klimova 12 particularly emphasize the very frequent coincidence of the lesion with the anatomical disposition of nutrient arteries. What causes these vascular disturbances is unknown. T r e a t m e n t . In cases with vertebral location complete local excision, when possible, is the treatment of choice. Failing this, careful curettage should be carried out. Some authors 3, 14, 16 claim that curettage alone is sufficient for cure. According to Jaffe 11, Lichtenstein 14, Besse et al. 3, the patient may be cured if curettage is incomplete, as in our second case. The surgical treatment of the vertebral cyst may become difficult because of extensive haemorrhage or inaccessibility. R a d i o t h e r a p y . From the literature it appears that the reasons for including radiotherapy in the treatment are based on several concepts. According to Taylor 25 and Carlson 5 radiotherapy should be reserved for surgical failure or for situations where surgical access is difficult or impossible. Others 7, 8, 26, 27 say irradiation may be used as an adjunct to surgical treatment. Initial radiation therapy was given by Biesecker et al. 4. Advocates of radiation therapy as primary treatment of choice are Nobler et al. is, and Kubicz la, who have reported excellent results. The recommended doses are between 1,200 and 3,000 rads 4, s, as, 2i, 27 Most authors ~, 16, ~7, ,9, 22, e~ consider that radiotherapy may not be necessary and should be used only exceptionally. Possible damage to the epiphyseal plate with subsequent interference with growth should preclude its use in the majority of cases. Especially in vertebral cases damage to the spinal cord and sterilisation are risks which must be considered. As sarcomas have been reported 8, 14, 21, 2~ in irradiated sites, radiation therapy should be used judiciously in treating this benign lesion. This is not the only reason for the usual note of caution in regard to radiotherapy. As spontaneous healing of an aneurysmal bone cyst may occur 22, 24 it appears that there are no absolute indications for its use. On the other hand there are observations which demonstrate the ineffectivenes of radiotherapy. Kagan and Klimova le reported a case treated first as reticulosarcoma of the femur with 6~ (7,500 rads tumour dose) without improvement. The right diagnosis of aneurysmal bone cyst was established after surgical removal, performed two months later because of the persistence of complaints and the roentgenologic findings. In our first patient (case 1), despite radiotherapy, there was a recurrence in the form of asymptomatic small cystic lesions. This was one of the reasons for our decision not to apply radiation therapy in the second patient (Case 2), in spite of incomplete removal. Spontaneous cure and recurrence. The tendency of the process
Aneurysmal Bone Cyst of the Spine
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to heal spontaneously is reported by several authors 1, s, la, 19, 22, 2,~ Sherman and Soong 24 have noted spontaneous calcification of an aneurysmai bone cyst of the third lumbar vertebra without any treatment. Biopsy was not performed. Rigault et al. 22 have reported a case of aneurysmal bone cyst of the second cervical vertebra without histology, but with a typical X-ray picture, cured without surgery or radiotherapy, by nineteen months of immobilization. Our third patient resembles these cases. The favourable response of the process to even incomplete removal has been pointed out a, s, 14, 19, 27 In our second case this was the other reason which made us wait and see the result of the surgery and not proceed to postoperative radiotherapy. The spinal lesion shows less tendency to relapse. Detection of residual cysts in the postoperative period, or appearance of new cysts on the control roentgenograms, are not a reliable indication that recurrence will follow and that operative interference is needed. As long as these relatively small cysts do not cause clinical manifestations our attitude should be expective, keeping the patient under close control. We must not neglect the fact pointed out by Tillman et al. 20 that the frequency of recurrence decreases with age and depends on the location of the process. Differential diagnosis. In spite of the numerous lesions that resemble aneurysmal bone cyst, the correct diagnosis can be made with confidence, especially in cases with vertebral location where the number of diagnostic possibilities seems to be limited. Most of the cases with vertebral aneurysmal bone cyst have been first diagnosed histologically as giant cell tumours. This lesion may contain in some instances spaces filled with blood or serous fluid, but the cellular zones are devoid of fibrous or bone tissue ~, 7, 8, 26 Dabska and Buraczewski s pointed out that giant cell tumour does not produce osteoid tissue unless irradiated. The presence of small multinuclear giant cells seems to be responsible for the frequent confusion of aneurysmal bone cyst with giant cell turnout. In aneurysmal bone cyst the differentiating feature is the presence of islets of osteoid and new bone which appear to have a reparative function v, 14 It is important to note that giant cell tumours are extremely rare in the spine above the sacrum 9, 16, ~9, 26 and before the age of twenty. Paillas et al. 19 draw attention to the fact that the osteolytic process is usually much more expansive in the aneurysmal bone cyst than in the giant cell turnout. In any case the X-ray examination, the clinical picture, and the histology should all be considered together carefully for diagnosis to be made and treatment planned,
112
M. Karparov and D. Kitov: References
1. Barnes, R., Aneurysmal bone cyst. J. Bone Jt Surg. 38-B (1956), 301--311. 2. Beeler, J. W., Helmann, C. H., Campell, J. A., AneurysmaI bone cyst of spine. JAMA 163 (1957), 914--918. 3. Besse, B. E., Dahlin, D. C., Pugh, D. G., Ghormley, R. K., Aneurysmal bone cyst, additional considerations. Clin. Orthop. 7 (1956), 93--98. 4. Biescker, J. L., Marcove, R. C., Huvos, A. G., Mike, V., Aneurysmal bone cysts. Cancer 26 (1970), 618--625. 5. Carlson, D. H., Wilkinson, R. H., Bhakkaviziam, A., Aneurysmal bone cysts in children. Amer. J. Roentgenol. 116 (1972), 644--650. 6. Clough, J. R., Price, C. H. G., Aneurysmal bone cysts. J. Bone Jt. Surg. 50-B, (1968), 116--127. 7. Crabbe, W. A., Aneurysmal bone cyst and its atypical features. Guy's Hosp. Rep. 111 (1962), 347--354. 8. Dabska, M., Buraczewski, J., Aneurysmal bone cyst. Pathology, Clinical course and radiologic appearances. Cancer 23 (1969), 371--389. 9. Dominok, G. W., Knoch, H. G., Knochengeschwiilste und geschwulst~.hnliehe Knochenerkrankungen, pp. 289--302. Jena: VEB G. Fischer. 1971. 10. Donaldson, W. F., Aneurysmal bone cyst. J. Bone Jt. Surg. 44-A (1962), 25--40. 11. Jaffa, H. J., Lichtenstein, L., Solitary unicameral bone cyst with lymphasis on roentgen picture, pathologic appearance and pathogenesis. Arch. Surg. 44 (1942), 1004--1025. 12. Kagan, E. M., Klimova, M. K., Aneurysmal bone cysts. Vesm. Roentgenol. and Radiol. (Moscow) 2 (1965), 3--9. 13. Kubicz, S., Aspect radiologique du kyste osseux an~vrysmal chez l'enfant. Ann. Radiol. 13 (1970), 211--218. 14. Lichtenstein, L., Aneurysmal bone cyst, further observations. Cancer 6 (1953), 1228--1237. I5. Lichtenstein, L., Aneurysmal bone cyst: Observations on fifty cases. J. Bone Jr. Surg. 39-A (1957), 873--882. 16. McCarty, C. S., Dahlin, D. C., Doyle, J. B., Lipscomb, P. R., Pugh, D. G., Aneurysmal bone cyst of the neural axis. J. Neurosurg. I8 (1961), 671--677. 17. Mastragostino, S., Candle, G., Aneurysmal bone cysts. Lo Scalpello (1973), 95--114. 18. Nobler, M. P., Higinbotham, H. L., Phillips, R. F., Irradiation superior to surgery in an analysis of 33 cases. Radiology 90 (1960), 1185--1192. 19. Paillas, J. E., Serratrice, G., Legr~, J., Les tumeurs primitifs du rachis, pp. 65--82. Paris: Masson. 1963. 20. Palma, V., Venturinni, G., Su di un caso di cisn aneurismatica ossea a duplice localizzazione. Minerva Ortop. 10 (1959), 739--742. 21. Prakash, B., Banerji, A. K., Tandon, P. M., Aneurysmal bone cyst of the spine. J. Neurol. Neurosurg. Psychiatr. 36 (1973), 112--117. 22. Rigault, P., Beneux, J., Desvignes, P., Le kyste anevrysmal des os chez l'enfant. Ann. P~diat. 19 (1972), 223--234. 23. Sabanas, A. O., Dahlin, D. C., Childs, D. C., Dins, J. C., Postradiation sarcoma of bone. Cancer 9 (1956), 528--542. 24. Sherman, R. S., Soong, K. J., Aneurysmal bone cyst: Its Roentgen Diagnosis. Radiology 68 (1957), 54--64. 25. Taylor, F. W., Aneurysmal bone cyst. J. Bone Jr. Surg. 38-B (1956), 293--300.
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26. Tillman, B. P., Dahlin, D. C., Lipscomb, P. R., Stewart, J. R., Aneurysmal bone cyst: an analysis of ninety five cases. Mayo Clin. Proc. 43 (1968), 478--495. 27. Tzivkin, M. V., Panichev, A. F., Vahrushev, E. H., Comparative evaluation of the therapeutic methods by aneurysmal bone cysts of the spine. Vestn. Khirur. Grecova (Moscow), 112 (1974), 64--68. 28. Verbiest, H., Giant cell tumors and aneurysmal bone cyst of spine. J. Bone Jt. Surg. 47-B (1965), 699--713. Authors' address: Assis. Prof. Dr. M. Karparov, Radioisotopic Centre, and Prof. Dr. D. Kitov, Neurosurgical Clinic, Faculty of Medicine "I.P. Pavlov", Plovdiv, Bulgaria.
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