Tiirkisli Neiirosiirgerii 11: 60 - 64, 1001

Monostotic FibrousTemporal Bone:

Beknr: Maiiaslolir Fibraiis Dysplasin of Ilie Teiiipoml Boiie

Dysplasia of theA Case Report

Temporal Kemigin Monostotic Fibröz Displazisi:Olgu Sunumu

AHMET BEKAR, KUDRET TÜREYEN, TEOMAN CORDAN

Uludag University, School of Medicine Department of Neurosurgery, Bursa, Turkey

Received : 1.8.1999 <:::> Accepted : 10.3.2000

Absiracl: Fibrous dysplasia is a congenital, nonfamilial,metabolic disturbance that produces 2.5'70 of aii osseoustumors, and more than 7% of all nonmalignant tumors inbone. Involvement of the temporal bone, however, isrelatively rare. An 8-year-old girl presented withprogressive hearing loss. She had a mass in the left externalacoustic meatus and hearing loss in her left ear.Radiological studies revealed a temporal mass. The patientunderwent two surgeries in 2 months, and the mass wastotaiiy excised. A postoperative neurologic examinationrevealed left facial paralysis. Histological study identifiedthe mass as fibrous dysplasia of bone. After 5 years offollow-up, there were no signs of residual tumor orrecurrence of the disease. When indicated, total excisionwith extensive reconstruction is the treatment of choice

for this type of bone neoplasm.

Key Words: Fibrous dysplasia; temporal bone; tumor;acoustic meatus

INTRODUCTION

In 1938, Liechtenstein coined the term "fibrousdysplasia" to deseribe a condition characterized bythe progressive replacement of normal bone elementswith fibrous tissue (9). Fibrous dysplasia is a

60

Özel: Fibröz displazi, kemigin bütün benign tümörlerinin0/07'sinden fazlasinda ve bütün kemik tümörlerinin

0/0 2.5' inde görülen, ailevi olmayan, konjenital ve metabolikbir hastaliktir. Temporal kemigin tutulumu oldukçanadirdir. 8 yasinda kiz çocugu, ilerleyici isitme kaybi ilebasvurdu. Sol kulakta isitme kaybi ve eksternal akustikkanalda kitle tespit edildi. Radyolojik incelemeler

temporal kitle gösterdi. Hasta 2 ay içinde iki kez opereedilerek kitle totalolarak çikarildi. Postoperatifmuayenede solda fasiyal paralizisi vardi. Histopatolojiktani fibröz displazi olarak alindi. 5 yillik takipte rezidüveya rekürrens tespit edilmedi. Fibröz dispbzi gibi kemik

tümörlerinde, endike oldugu zaman, genisrekonstrüksiyon ile birlikte total rezeksiyon seçilecektedavidir.

Anahtar kelimeler: Fibröz displazi; temporal kemik;tümör; akustik kanal

congenital, nonfamilial, metabolic disorder thatproduces 2.5% of all osseous tumors, and more than7% of all nonmalignant bone tumors (4,5,10,15). Theaverage age at onset is 10 years (5). Sometimes thisneoplastic process is associated with abnormal skinpigmentation or endocrine abnormalities. The lesion

Tiirkish Neiirosiirgery 11: 60 - 64, 2001

may involve one skeletal bone (monostotic) or severalbones concurrently (polyostotic). The monostoticform is most common (70%) (12),with the polyostotictype accounting for 30% of fibrous dysplasia cases(11). Involvement of temporal bone is relatively rare(1). We report the case of a pediatric female patientwho had fibrous dysplasia of the temporal bone, andreview the relevant literature on this form of

neoplasia.

CASE REPORT

An 8-year-old gir! was admitted to ourdepartment with a history of recurrent external otitisand the complaint of gradual hearing loss in the leftear. Her physical examination revealed a mass thatwas narrowing the external acoustic meatus of theleft ear such that the tympanic membrane could notbe visualized. No abnormal ski n pigmentation wasdetected on the patient's body.

Audiologic testing confirmed that the hearingloss was of the mixed conductive type. Laboratoryresults indicated there were no biochemicalabnormalities. Plain x-rays of the skull, indudingoblique views, showed a well-circumscribedprotrusion of the squamous portion of the temporalbone, with curvilinear calcification. Erosion of theoccipital bone was also evident. A computerizedtomography (CT) scan of the region of the lefttemporal bone show ed stenosis of the externalacoustic meatus, and narrowing of the tympanic

Bekar: Moiioslotic Fibroiis Dysp/asia of Ihe Teli/para/ Boiie

cavity and the internal ear canal. CT also revealedthat the mass had invaded the bone to the level of

the middle fossa and the prepontine angle (Figure1a,b,c). Digital subtraction angiography showed thatthe tumor' s vascular supply was the external carotidartery and its posterior auricular, middle meningealand occipital branches. Magnetic resonance imaging(MRI) showed a lesion with low and high signalintensity on Tl-weighted images, and low signalintensity on T2-weighted images. Intravenousgadolinium injection revealed a markedly enhancedextraaxial mass (Figure 2). We were not able to assessthe patient with radionudide scintigraphy.

Figure 1:The CT appearance of the lesion with and without contrast demonstrates partial blockage of the external acousticmeatus and narrowing of the tympanic cavity and internal ear canal (a,b), and tumor invasion to the level of themiddle fossa and prepontine angle (c).

61

Tiirkish Neiirosiirgery 11: 60 - 64, 2001

Figure 2: The appearanee of the lesion on eontrast­enhaneed eorenal MR!.

The first step in treatment was embolization ofthe left posterior auricular and occipital arteries usingpolyvinyl akohol injection. Once this was complete,we used a left petroclival surgical approach toremove the tumor. Grossly, the lesion was asubcutaneous mass of dense sderotic material

composed of vascular fibrous substance and bone. itextended to the pyramis of the temporal bone. Wedid a partial mastoidectomy, and observed that theincus and stapes had been destroyed by the invasivedisease in the narrowed middle ear. We also noted

that the facial nerve was surrounded by fibrousdysplastic bone, and we carefully resected this tumortissue.

In this initial surgery, only subtotal resection ofthe tumor was possible due to intraoperativeproblems with massiye hemorrhage andhypotension. However, 2 months later, we did asecond operation. In this procedure, we used thesame incision, removed the remainder of the mastoidprocess, performed a petrosectomy and resected thepart of the tumor that had invaded the occipital bone.The mass did not involve the dura mater, and therewas no damage to this structure during surgery.Facial nerve anastomosis was not possible due to thelarge defect created by the petrous bone resection.The postoperative neurologic exam revealed leftfacial paralysis.

Histological examination confirmed that thelesion was fibrous dysplasia of bone. The mass was

62

Beknr: Moiiostotic Fibroiis Dyspinsin of the Temporal Boiie

composed of moderately cellular fibrous stroma withuniform, benign-looking spindle cells. Throughoutthe stroma there were foci of irregularly shapedtrabeculae of immature woven bone. There was noevidence of recurrence or residual tumor at 5 yearspostsurgery (Figure 3), but the patient's facialparalysis and left hearing loss remained unchanged.

Figure 3: Postoperative CT sean of the site of interest at 5years after the patient's final surgery.

DISCUSSION

Fibrous or fibroosseous dysplasia occurs inthree forms: a) Monostotic, when only a single boneis affected; b) Polyostotic, when several or manybones are involved, either unilaterally or bilaterally;and c) Polyostotic with endocrine abnormalities,including any combination of precocious puberty,cafe-au-lait spots (McCunne-Albright syndrome),goiter, hyperthyroidism, Cushing' s disease andacromegaly (20). In the skull, fibrous dysplasia isknown to involve the ethmoid, sphenoid, frontal andtemporal bones, in decreasing order, respectively(5,11,15,18).

it is reported that only 10% of patients withmonostotic fibrous dysplasia have craniofacial boneinvolvement (13,20). Van Tilburg et aL.reviewed 144cases of skull involvement in monostotic and

polyostotic disease. They found that the frontal andsphenoid bones were most often affected, and thatthe temporal bone was affected in only 18% of cases(19). The prevalence of temporal bone involvementof fibrous dysplasia in males is double the figure

TurkisTi Neurosiirgery 11: 60 - 64, 2001

noted in females (7). The disease most of ten appearsin Iate childhood or early adolescence, and is rarelyseen in adults (3,10,13). Our patient was 8 years old,and presented with hearing loss, a history ofrecurrent external otitis and a mass that was almost

totaiiy obstructing the external acoustic meatus. Themost common sign of fibrous dysplasia at this site isprogressive protrusion of the mastoid or squamousportion of the temporal bone, occasionaiiy with apreauricular protrusion that may interfere withtemporomandibular joint mobility. The lesion mayalso result in cranial nerve (CN) palsy, with CN VIImost commonly involved 01,20).

Regarding diagnosis, the three major groups inthe radiographic dassification of fibrous dysplasiaare pagetoid, sderotic and eystic lesions 0,6,11). Theradiographic features of the disease vary dependingon the stage of development and amount of bonymatrix within the lesion. CT evaluation is useful for

documenting the extent of bone and extraosseousinvolvement 0,4,10,11,14,15). We confirmed our

patient's diagnosis on CT. Radionudide scintigraphicevaluation is another important tool for detectingfibrous dysplasia. This type of sean is diagnosticwhen over 50% of the calcified bone at the diseased

site is replaced by fibrous tissue. Radionudide studiesare mare specific than CT for deIineating the intra­and extraosseous extent of the lesion, and for

demonstrating polyostotic or disseminated disease(8,10). Unfortunately, we were unable to perform aradionudide examination on our patient.

The differential diagnosis for fibrous dysplasiaindudes giant cell granuloma, ameloblastic fibroma,osteoma, odontogenic cyst, hyperparathyroidism,juvenile Paget's disease, chronichyperphosphatasemia tarda, the Hunter-Hurlersyndrome of gargoylism, cherubism,neurofibromatosis and tuberous sclerosis(4,5,10,11,13).

Surgical management is not always indicatedin these cases. Smaii soIitary lesions will usuaiiyremain static and asymptomatic. However, surgicalexcision and cureHage are required when markedprogressive bone deformity, cranial nervecompromise or pain syndromes are manifested.Unless neurological compromise becomes evident,it is recommended that surgical intervention bedelayed until adolescence or until growth iscompleted (10). Our cas e called for immediatesurgery because the mass was compressing the

Beknr: MOllOStotic Fibroiis Dyspinsin of tTie Teiiipoml Boiie

patient's brainstem and the bulb of the jugular vein.We were abI e to totaiiy excise the tumor through apetrodival approach.

Serious intraoperative vascular compIicationsdeveloped in both surgeries that were done in thiscase. The patient's preoperative angiographic wark­up indicated that the mass was receiving arterialsupply from branches of the external carotid and theposterior circulation; thus, our first step was toembolize the feeding vessels. Aii signs indicated thatthis procedure had been successful, but severehypotension developed in the first surgery due tomassiye bleeding through blood transfusion. Facedwith this urgent situation, we were only able to resectpart of the tumor. We completed the excision in thesecond operation, but, although no embolization wasperformed in that session, we encountered similarhemorrhage once again.

In terms of outcome, fibrous dysplasia is abenign condition that has a good prognosis. Thedisease process is usuaiiy halted at puberty; however,Ramsey et aL. and Harris and colleagues have

reported cases where progression has contii1ued (20).Hormone treatment is reportedly ineffective, andadjuvant irradiation is contraindicated given the highpotential for malignant transformation (7,13,16,17).Chen and Fairholm reported 11 cases of maIignanttransformation in 13 patients who received this formof therapy (2). In patients with monostotic disease,the prevalence of maIignant degeneration is highestin lesions that affect the craniofacial region (0).Overali, this translates into a 0.5% risk of malignanttransformation for fibrous dysplasia lesions that areleft untreated. One study has indicated that the meaninterval between diagnosis of the condition and thedevelopment of maIignancy is 13.5 years (5).

Finaiiy, decision-making can be difficult incertain situations, and the finding of an aggressiveform of fibrous dysplasia in a preadolescent patientpresents the surgeon with the toughest dilernma.When indicated, complete resection with extensivereconstruction is the treatment of choice.

Correspondence: Ahmet BekarAssistant Professor of Neurosurgery,Uludag University School of Medicine,Department of Neurosurgery16059 Bursa, TurkeyTel: 90.224.4428081Fax: 90.224.4428034

e-mail: dr_ahmet_bekar@hotmai1.com

63

Tiirkis/i Neiirosiirgery 11: 60 - 64, 2001

This mmiiiscript was presented in poster format the XII Annual Scientific Congress of theTurkish Neiirosurgical Society, in Aiitalya, Turkeyin 1998.

Acknowledgement:We thank Mr. Fikri Öztop (Professor of

Pathologij, Ege University, Izmir) for his pathologicalassessment, and Mr. Ogl/Z Basilt (Assistant Professorof ENT, Ull/dag University, BIlrsa) for his ENTassessment of this case.

REFERENCES

1. Brown EW, Megerian CA, McKenna MJ, Weber A:Fibrous dysplasia of the temporal bone: Imagingfindings. AJR 164(3):679-682, 1995

2. Chen YR,Fairholm D: Fronto-orbit-sphenoidal fibrousdysplasia. Ann Plast Surg 15:190-203, 1985

3. Davies ML, Macpherson P: Fibrous dysplasia of theskull: Disease activity in relation to age. British JRadiolog 64:576-579, 1991

4. Di Rocco C, Marchese E, Velardi F: Fibrous dysplasiaof the skull in children. Pediatric Neurosurgery 18:117­126, 1992

5. Edgerton MT, Persing JA, Jane JA: The surgicaltreatment of fibrous dysplasia: With emphasis onrecent contributions from cranio-maxillo-facialsurgery. Ann Surg 202:459-479, 1985

6. Frier JW: The roentgen features of fibrous dysplasia ofthe skull and facial bones. A critical analysis of 39pathologically proven cases. AJR 77:71-88,1957

7. Harrison DFN: Unusual tumors, in Sven JY, Myers EN(eds), Cancer of the Head and Neck, New York:

64

Beknr: Mol/oslolic Fibroiis Dysplasin of i/ie Tempornl Boiie

Churchill-livingstone, 1981:829-8768. Lambert PR, Brackman DE: Fibrous dysplasia of the

temporal bone: The use of computerized tomography.Otolaryngol, Head and Neck Surg 92:461-467,1984

9. lichtenstein L, Saffe HL: Polyostotic fibrous dysplasia.Arch Surg 36:874, 1938

10. Michael L, Thomas C, Martin W: Monostotic fibrousdysplasia of the elivus: Case report. J Neurosurg 75:800­803, 1991

11. Mohammadi-Araghi H, Haery c: Fibro-osseous lesionsof craniofacial bones: The role of imaging. Radiol Clinof North Am 31(1):121-134, 1993

12. Nager GT and Holliday MJ: Fibrous dysplasia of thetemporal bone: Update with case report. Ann Otolog,Rhinolog and Laryngol 93:630-637, 1984

13. Pecaro BC:Fibro-osseous lesions of the head and neck.Otolaryngol Clin North Am. 19(3):489-496, 1986

14. Pouwels ABPM, Cremers CWRJ: Fibrous dysplasia ofthe temporal bone. J Laryngol and Otolog 102:171-172,1988

15. Pritchard JE: Fibrous dysplasia of the bones. Am J MedSci 22:313-332, 1951

16. Ruggieri P, Sim H, Bond J, Uni K: Malignancies infibrous dysplasia. Cancer 75(5):1411-1424, 1994

17. Schwartz DT, Alpert M: The malignant transformationof fibrous dysplasia. Am J Med Sci 247:1-20, 1964

18. Sharp M: Monostotic fibrous dysplasia of the temporalbone. J Laryngol and Otolog 84:697-708, 1970

19. Van Tilburg W: Fibrous dysplasia, inVinken PJ, BruynGW (eds), Handbook of Clinical Neurology,Amsterdam: North Holland Publishing Co, 1972:163­212

20. Younus M, Haleem A: Monostotic fibrous dysplasiaof the temporal bone. J Laryngol and Otolog 101:1070­107,1987