Aneurysmal Bone Cyst Of Sphenoid Bone- A Case Report

Aneurysmal Bone Cyst of Sphenoid BoneA Case ReportME Karimi, MZ Haque2Bangladesh Med. Res. Counc. Bull. 2005; 31(3): 117-121SummaryAneurysmal bone cysts of the skull are rare and involvement of sphenoidbone is even less frequent. We present X-ray, CT, MR imaging andhistopathologic findings of an aneurismal bone cyst of the sphenoid in a ISyears old female adolescent. Radiological findings of the aneurysmal bonecyst of the skull were highly suggestive of the diagnosis and that wereconfirmed by histopathologic analysis.Introductionthan I % of all aneurysmal bone cysts3.Painand swelling are the most common overallpresentation. Plain film & Non Enhanced CT(NECT) scan shows osteolytic lesionsurroundedby expanded, thinned, egg shelllike cortical bone. A soft tissue mass isoften present. Matrix Calcification isabsent. Most ABCs are very hypervascularat angiography4. MR scan typicallydemonstrate a lobulated, multi septatedlesion with fluid-fluid levels and bloodAneurysmal bone cysts (ABCs) areuncommon benign, non-neoplastic cysts ofunknown origin. In one third of cases, ahistory of trauma or a preexisting osseouslesions such as chondroblastoma, Gient CellTumour (GCT), osteoblastoma,NonOffifying Fibroma (NOF) or fibrousdysplasia are present1.2.Rapid expansionmay obliterate the underlying abnormality,leaving behind the blood-filled cavities thatdegradation products. Wepresent X-ray, CT,are characteristics of ABCs. Grossly, ABCsMR imaging findings in the case of ABCare multilocuated, expansile and highlyof sphenoid that was confirmed byvascular osteolytic lesions that often containhistopathologic findings.blood degradation products. This rareentity commonly occur below 20 yrs. ofCase Reportage with slight female preponderance.ABCs occur in all parts of skeleton, mostly A I5-years old female adolescent had paininvolving the metaphysis of long bone and and watering of right eye as well as headacheneural arches of vertebrae1.2. Skulland nausea over a period of 03 months. Theinvolvement is rare, occurring in less patient noticed gradual swelling over her1. Deptt. of Radiology & Imaging, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka.2. MD Student (Thesis Part).117

Vol. 31, No.3Aneurysmal Bone Cyst of Sphenoid Bone ME Karim et al.right orbital region. She had no history oftrauma or surgery. Physical examinationrevealed swelling of right orbital regionassociated with exopthalmos of eye. Ocularmovement was restricted but visual acuitywas normal. Fundoscopy was unremarkable.X-ray skull AP and Lateral view showedenlargement of right orbit with destructionof lesser and greater wing of right sphenoid(Fig.-1). Onaxialandcoronalcr scans, a welldefined multiloculated mixed density mass Fig.-l: Plain x-ray skull PIA view-showing rightwith fluid-fluid levels was found in middle orbit is enlarged with destruction of lesser andcranial fossa involving right temporal & greater wing of sphenoid bone at right side.infratemporal fossa, ethmoid & sphenoidsinuses, posterior aspect of nasopharynx,anteriorly extending in to right orbital cavity,superiorly in to right frontal region. Bonedestructions was present in lesser and greaterwing of sphenoid, ethmoid and orbital plateof maxilla. The mass showed strongenhancementin post contrast scan (Fig-2&3).TIW, T2W and post gadolinium contrastMR imaging revealed strongly enhancing Fig.-2: Contrast enhanced axial CT scan ofvariable signal intensity lobulated mass with brain shows-heterogeneous enhancing masSfluid-fluid level within the cystic spaces, lesion with cystif component, few having fluidfluid levels.consistent with blood degradation products.The mass involved right cavernous sinus,encasing the right Internal Carotide Artery(ICA) (Fig.-4, 5, 6 & 7). Near total removalof the mass was done surgically.Histopathologic analysis revealed graywhite soft tissue mass with blood filledcystic spaces. The lesion was made ofmany osteoclastic giant cells in thebackground of spindle shaped stromal cells.Some of the cystic spaces were devoid ofendothelial lining. Bone formation is seen Fig.-3:Bone window setting of CT scan ofbrain showing destruction of right greater andwithin the lesion.These findingswere consis- lesser wing and part of the sphenoid bone astent with those of an aneurysmal bone cyst. well as right ethmoid bone.118

Bangladesh Med. Res. Coune. BullDecember 2005DiscussionABCs were first described in 1942 as"peculiar blood-containing cysts of largesize"5. They are composed of blood-filled,anastomosingcavernous spaces, separatedbycystlike walls. The exact etiology is not clear.However, the ABC is considered to be theFig.-4: Noncontrast axial Tl W MR image ofbrain shows- mixed intensity mass lesionhaving fluid fluid levels.Fig.-S: Axial T2W MR image of brain showsheterogeneous hyperintensity mass lesionhaving fluid fluid levels.Fig.-6&7: Pre and post contrast parasagittalMR images of brain shows heterogeneousstrong enhancement of the lesion.result of a specific pathophysiolQgicchanges,which is probably caused by trauma or ananomalous vascular process. The lesion is acomponent of, or arises within a preexistingbone tumor in about one third of cases. AnABC can arise from a preexistingchondroblastoma,a chondromyxoid fibroma,an osteoblastoma, a giant cell tumor orfibrous dysplasia. Less frequently, it resultsfrom s.ome malignant tumours, such asosteosarcoma, chondrosarcomaandhemangioendothelioma 1.2.ABC rarely involves the skull and can occurin any part of it. Sizes of the frontal ABCswere reported within 4-6 cm in ologic properties of an ABC.Initially, well-defined osteolysis andperiosteal elevation are present. The lesiongrows rapidly & causes progressivedestruction. Radiographs typically show aneccentric lesionwith an expanded, re- odeledblown out or ballooned bony contour of thebone. The expanded contour is the result ofbone production by the periosteum. Lesionsfrequently have a delicate trabeculatedappearance). At histologic examination,these lesions are large, septated sinusoidsfilled with blood and lined by endotheliumand multinucleatedgiantcells7.8.Haemorrhageof variable age within the cysts119

Vol. 31, No.3Aneurysmal Bone Cyst of Sphenoid Bone ME Karim et aI.To the best of our knowledge, this is the firstcase report of ABC involving tile sphenoidbone of skull from Bangladesh.are present and the degradation of bloodproducts causes fluid levels.CT is superior in the evaluation of the lesionslocated in the regions that cannot be assessedwell by radiography. CT scan can clearlydemonstrate the extent of mass and bonedestruction. Fluid levels are observed is 35%of the cases, and dependentincreased attenuation I.ABC should be considered in rapidlygrowing calvarial masses in adolescents. CTscan and MR images showing stronglyenhancing well defined loculated soft tissuemass having fluid-fluid level sugge-st thepresence of ABC. Especially the MRimaging is important in the evaluation ofneighbouring structures before surgicalintervention.layer showOn MR images, the hypointense rimsurrounding the lesion is an importantfinding and suggest a benign process. This Referencesrim is composed of fibrous tissueI,8.9.Afluid-fluid level is another finding and is I. Kransdorf MJ, Sweet DF. Aneurysmalbone cyst: concept, controversy, clinicalmore readily seen on MR images than onpresentation, and imaging. AJR Am JCT scansl. Fluid-fluid level caused by theRoentgenol1995; 164: 573-80.degradatio'n of blood product stronglysuggest the presence of ABC7 but this 2. Martinej V,Sissons HA. Aneurysmal bonecyst: a review of 123 cases includingfinding has been reported to occur inprimary lesions and those secondary toassociation with various condition andisnot pathognomic.Chondroblastoma,osteosarcoma, giant cell tumor, Fibrousdisplasia, osteoblastomaand tumor calcinosis 3.also show fluid-fluid levellO.ll.Although it isnot specific, its presence indicates an ABCif other suggestive feature existl2. Anotherimportant MR imaging finding is the 4.presence of small cysts produced from largercysts, these are called diverticula7.8.other bone pathology. Cancer 1988; 61:229-2304.Hunter JV, Yokoyama C, Moseley IF,Wright JL. Aneurysmal bone cyst of thespheroid with orbital involvement. Br JOphthalmol 1990; 74: 505-8.De Santos L, Murray JA. The value ofarteriography in the management ofaneurysmalbone cyst. SkeletalRadio11978;2: 137.Considering the age, clinical features andradiological findings of our patient, theradiological diagnosis was suggestive ofaneurysmal bone cyst. Fluid-fluid level,diverticula and enhancementof fibrous tissue5.Jaffe HL, Lichtenstein L. Solitaryunicameral bone cyst with emphasis on theroentgenpicture,the pathologicappearance and the pathogenesis. ArchSurg 1995; 96: 440-5.in MR images were considered typical ofan ABC.6.O'Brein DP,Rashad EM, TolandJA, FarrelMA, Phillips J. Aneurysmal cyst of the120

December 2005Bangladesh Med. Res. Counc. Bullfrontal bone: case report and review of theliterature. Brit J Neurosurg 1994; 8: 105-87.Beltran J, Simon DC, Levy M, HermanL, Weis L, Mueller CF. Aneurysmalbone cyst: MR imaging at 1.5T.Radiology1986; 156: 689-90.8.Musk PL, Helms CA, Hott G, Johnston J,Steinbach L, Neumann C. MR imaging ofaneurysmal bone cysts. AJR Am JRoentgenol 1988; 153: 99-1019.Zimmer WD, Berquist TH, Mecleod RA,et aJ. Bone tumors: magnetic resonanceimaging versus computed tomography.Radiology 1985; 155: 709-18.10. Tsai JC, Dalinka MK, Fallon MD, ZlalkinMB, Kressel HY. Fluid-fluid level: anonspecific finding in tumors of bone andsoft tissue. Radiology 1990; 175:779-82.11. Vilanova JC, Dols JL, Maestro de leonJL, Aparicio A, aldom J, Capdevila A.MR imagingof a malignantschwannoma and an osteoblastoma withfluid-fluid levels: Report of two newcases. Eur Radiol 1998; 8: 1359-62.12. Shah GV,Aneurysmalbone: MRNeuroradiol121Doctor MR. Shah PS.bone cyst of the temporalfindings. AJNR Am J1995; 16: 763-6.

Aneurysmal Bone Cyst of Sphenoid Bone-A Case Report ME Karimi, MZ Haque2 Bangladesh Med. Res. Counc. Bull. 2005; 31(3): 117-121 Summary Aneurysmal bone cysts of the skull are rare and involvement of sphenoid bone is even less frequent. We present X-ray, CT, MR imaging and histopathologic findings of an aneurismal bone cyst of the sphenoid in a IS-