Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 51, Num. 1, 2003, pp. 121-123

Neurology India, Vol. 51, No. 1, Jan-Mar, 2003, pp. 121-123

Short Report

Intracranial aneurysmal bone cyst manifesting as a cerebellar mass

S. Kumar, T. M. Retnam, T. Krishnamoorthy,* S. Parameswaran, S. Nair, R. N. Bhattacharya, V. V. Radhakrishanan**

Departments of Neurosurgery, *Neuroradiology and **Neuropathology , Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapurum-695011, India.
Dr. V. V. Radhakrishnan, Department of Neuropathology, Sree Chitra Tirunal Institute For Medical Sciences and Technology, Thiruvananthapurum, Kerala, India. E-mail: vvr@sctimst.ker.nic.in

Accepted on 06.09.2001.

Code Number: ni03040

A 17-year-old boy presented with symptoms of raised intracranial pressure for a month. Investigations revealed a large extra-cerebellar mass. The lesion was radically resected. It arose from the petrous bone. Histology revealed that the lesion was an aneurysmal bone cyst [ABC].

Key Words: Aneurysmal bone cyst, Benign skull lesion, Intracranial lesion.

Aneurysmal bone cyst (ABC) is a benign bony lesion, first described by Jaffe and Lichtenstein in 1942. Most common anatomical location for its occurence of ABC is in the metaphyseal end of long bones and rarely occurs in the skull.^1-4 Most cases of ABC manifest before the age of 20 years.^3,4 They usually present as palpable skull masses. It is uncommon for calvarial ABC to manifest initially as an intracranial space-occupying lesion. A literature survey revealed 61 cases of ABC.⁵ We report a case of ABC occurring in the occipital region.

Case Report

A 17-year-old boy presented with history of headache of one month duration, which was occasionally relieved by bouts of vomiting. He also had dizziness for 2 weeks. Neurological examination revealed bilateral papilloedema. There was no palpable bony lesion over the calvarium. Systemic examination and examination of long bones were normal. Hemoglobin was 16 gm%. CT brain showed a circumscribed right cerebellar, mildly enhancing mass lesion with multiple internal loculations and fluid levels. The lesion caused mass effect on the fourth ventricle and there was a moderate hydrocephalus. MRI scan showed multiloculated isointense lesion on T1W1 with areas of hyperintensity and predominantly hyperintense lesion on T2W1.The mass caused edema in the right cerebellar hemisphere. There was contrast enhancement of septations and the walls (Figure 1). Angiography did not reveal any vascular lesion in the posterior fossa. The patient was taken up for surgery and a midline sub-occipital craniectomy was performed. A large, well-encapsulated, highly vascular tumor arising from the posterior- inferior petrous, posterior to the internal auditory meatus and jugular foramen was identified. There was a defect in the dura and bone at the site of attachment of the tumor. There was a good plane between the lesion and the cerebellum. The lesion had multiple loculi containing blood in different stages of degeneration. The lesion was completely resected.

Hematoxylin and eosin-stained sections showed numerous dilated blood spaces and they were devoid of endothelial cells. The vascular spaces were separated by collagenous and osteoid trabeculae, bordered by numerous multinucleated giant cells (osteoclast) (Figure 2). These histopathological findings were consistent with ABC.

The patient made an uneventful recovery.

Discussion

ABC is a benign non-neoplastic lesion of bone, commonly seen in the younger age group, usually before the age of twenty years.^2-4,6 Reviewing sixty-one cases, Sheikh et al⁵ observed that the majority of ABCs occurred in the temporal and occipital bones. The exact pathogenesis of ABC is not well known. Development of focal hemodynamic alterations with secondary venous hypertension was proposed by Lichtenstein.² Local trauma has also been incriminated in the development of ABC.^1,7,8 Bony lesions such as fibrous dysplasia, chondroblastoma, osteoclastoma, non-ossifying fibroma, giant cell tumor, fibromyxoma and unicameral bone cyst were demonstrated to be associated with ABC.^4,9,10

Several therapeutic modalities are used for the treatment of ABC, including complete surgical excision or curettage, radiotherapy, cryosurgery and endovascular embolization.^2,4,12,13

The treatment of choice for these lesions is total excision, as it is curative.^14,15 These lesions being non-neoplastic, the use of radiotherapy is not recommended although it is mentioned in literature.^2,3,14 For the same reason, chemotherapy has no role. Endovascular embolization plays an important role in preoperative devascularization of the lesion to reduce intraoperative bleeding. Endovascular embolization can be used in cases where the tumor is located in an area difficult for surgical resection.^12,16

References

1. Ameli NO, Abbassioun K. Aneurysmal bone cyst of the skull. Can J Neurol Scien 1984;11:466-71.
2. Rutter DJ, Van Rijseel THG. Aneurysmal bone cyst; a clinlcopathological study of 105 cases. Cancer 1977;39:2231-9.
3. Lichtenstein L. Aneurysmal bone cyst:observation of 50 cases. J Bone Joint Surg 1957;39:873-82.
4. Biesecker JL, Mike V. Neurymal bone cyst; a clinico pathological study of 66 cases. Cancer 1970;26:615-25.
5. Shiekh BY, et al. Acta Neurochir 1999;141;601-11.
6. Freeby JA, Wilson AJ. Quantitative analysis of plain radiographic appearance of anetuysmal bone cyst. Invest Radiol 1995;30:433-9.
7. Mufte ST, Aneurysmal bone cyst of skull. J Neurosurg 1978;49:730-3.
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9. Cacdac MA, Anderson PJ. Aneurysmal parietal bone cyst. J Neurosurg 1972;37:237-41.
10. Som PM, Schatz CJ. Aneurysmal bone cyst of the paranasal sinuses associated with fibrous dysplasia.CT and MRI findings. J Comput Assist Tomogr 1991;15:513-4.
11. Cataltepe O, Saglam S. Aneurysmal bone cyst of frontal bone. Surg Neurol 1990;33:391-5.
12. Cory DA, Scout JA DeRosa GP. Aneurysmal bone cyst; imaging finding and embolotherapy. 1989;153;369-73.
13. Lefebvrc CC, Roy D, Raymond J. Direct intmoperative sclerotherapy of aneurysmal bone cyst of sphenoid. AJNR Am J Neuroradiol 1996;17;870-2.
14. Dahlin DC, Mcleod RA. Aneurysmal bone cyst and other non neoplastic conditions. Skeletal Radiol 1982;8:243-50.
15. Bilge T, Covan O, Turker K. Surg Neurol 1993;20:227-30.
16. Chuang VP, Benjamin RS. Arterail occlusion, management of giant cell tumor and aneurysmal bone cyst. AJR Am J Roentgenol 1981;136:1127-30.
17. Chalapati Rao KU, Subba Rao B, Pulla Reddy C. Aneurysmal bone cyst of skull. J Neurosurg 1977;47L:633-6.

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