Journal of the Korean Radiologica l Society 1995 ; 33(3) : 351 - 356

Ameloblastoma ofthe Mandible and Maxilla:

CT Findings1

Jong Deok Kim, M.D. , JaeYoung Choi , M.D.

Purpose: To describe the characteristic CT findings of ameloblastomas in the mandibleand maxilla .

Materials and Methods: CT findings of 11 patients with ameloblastoma(9 cases in the mandible and 2 cases in the maxilla} proved by excisional biopsy were evaluated retrospectively with regard to the location , size, multilocularity, solid and cystic component , cortical destruction , soft tissue invasion , and contrast en­hancement

Results: Thesewere 8 multilculer expansile and 1 unicystic (developed in a den­tigerous cyst) mandibler ameloblasftomas, and 2 unilocular maxillary amelo­blasftomas. AII cases showed inhomogenously enhancing solid component, nine of which were larger than cystic component. Ninecases, largerthan 5 cm in diam­eter, revealed either a focal or extensive cortical destruction with various degree of invasion into the adjacent structures. One maxillary ameloblastoma contained a thick calcification along the margin ofthe lesion.

Conclusion: Maxillomandibular ameloblastomas appeared as expansile lesion containing enhancing solid component relatively larger than cystic portion and having cortical destruction in large lesions(5cm> ). Maxillary ameloblastomas were unilocular in appearance in spite of multilocularity in mandibular coun­terparts.

Index Words: Jaw, CT Jaw, neoplasms

Although the ameloblastoma is the most common tumor that arises from the epithelial components ofthe embryonic tooth , this tumor comprises only 1 % of ali jaw cysts and tumors. Eighty percent of ameloblas­tomas are located in the mandible and the remaining 20 % are found in the maxilla(1 -3)‘ As painless sweli ­ing is the most common early symptom of ameloblas­tomas in either jaw, delay in recognition of amelobl ­atoma is common and the time from onset of symptoms to treatment is often years. This slowly growing tumor is clinicaliy and histologicaliy benign , but it is localiy in­vasive with a high rate of recurrence. Since amelo­blastomas can proliferate within soft tissue, the detec tion of extracortical extent is of paramount importance

'Department of Diagnostic Radiology. College of Medicine, Inje University,

Pusan Paik Hospital ReceivedJune5, 1995 ; Accepted August9 , 1995 Address reprint requests to: Jong Deok Kim, M. 0., Department of Diagnostic Radiology, Coll egeof Medicine, Inje Universi ty, Pusan Paik Hospital, ~ 633-165, Gaegum-dong, Pusanj’n-ku , Pusan, 614-735 Korea

Tel. 82-51 -890-6549 Fax. 82- 51- 896-1 085

35 1

to the surgeon . CT plays an essential role not only in the diagnosis

but also in detection of encroachment into the sur­rounding structures(4 -6) . We report CT find ings of the ameloblastomas in the mandible and maxilla proved by surgical operation and histopathologic examination with review of the I iteratu re.

MATERIAlS and METHODS

Nine patients with primary ameloblastoma and two patients with recurrent ameloblastoma in the mandible 。 r maxilia were reviewed retrospectively. The diag­nosis was proved at surgery and pathologic exam in­ation in ali patients. There were 8 males and 3 females , with a mean age of 34 years(range, 12 -64 years) . AIi patients were exam ined wi th CT. At CT, contiguous axial and coronal sections 5 mm thick were obtained with either TCT -300S un it(Toshiba , Tokyo) or Somatom Plus unit(Siemens, Erlangen} before and after the ad­ministration of contrast material(drip infusion of 150 cc

Journal of the Korean Radiological Society 1995; 33(3) : 351-356

Ultravist 350 , SChering , Germany). Other radiologic examinations included plain radiography(posteroan­terior and both oblique mandible radiographs, dental radiographs , or occluded radiographs) and/or panor­amic radiography in all cases

CT findings were evaluated with regard to the loca­tion , size , multilocularity , solid and cystic component, cortical destruction , soft tissue invasion , and contrast enhancement ofthe lesions.

RESULTS

The computed tomographic analysis of 11 amelo­blastomas is shown in the Table 1.

Nine tumors were located in the mandible and two were located in the maxilla. Two of nine mandibular tumors were postoperative recurrent cases. The range 。f long diameter of the tumors was 3 -14.5 cm(mean , 8

cm) In the nine cases of mandibular ameloblastoma, ei­

ght tumors were multilocular. One unicystic amelo­blastoma of the mandible(developed in a dentigerous cyst) and two maxillary ameloblastomas were unilocu­lar. Each locule was larger than 1 cm in size in all cases except for two small mandibular tumors and the latter contained both large and small locules. Nine tumors , larger than 5 cm in diameter, revealed either focal or extensive cortical destruction with extension of the tumor into the adjacent structures , which ranged from a small localized mass formation to severe encroach­ment into the infratemporal or pterygopalatine fossa , masticator or buccal space , or orbit(Fig. 1). The rema­ining two tumors were smaller than 5 cm in diameter and they did not reveal cortical destruction.

AII ameloblastomas except one were mixed solid and cystic type. After the i 미 ection of contrast material ,

Fig. 1. 36-year-old female. Axial precontrast(a) and axial(b) and cor­onal(c) postcontrast CT scans show the ex­tensive destruction of the right mandible by a huge expansile, multilocular, solid and cystic mass. The mass extends into the infratemporal fossa and parapharyngeal space. Three-dimensional reconstruction CT image(d) shows an expansile lesion with extensive cortical ballooning and destruc­tlon

a b

c d

이 4 E

Since ameloblastomas originate within bone and grow slowly , early symptoms are usually absent or minimal. A painless mass is common in the mandibu­lar form of the disease, while nasal obstruction and 10-calized facial swelling are frequent in maxillary tu­mors. They may occur at any age , but the usual age at discovery is the fourth decade. Half of the mandibular lesions are located in the molar region and in the max­illa, approximately 50% are found in the molar region , 30 % in the area of antrum , and the rest at other sites , including less than 2 % in the anterior maxilla(6 -7)

There are three clinical types of ameloblastomas (8-11): (1) the solid intraosseous or m비ticystic type can be histologically invasive with a high rate of recur­rence , (2) the well -circumscribed unicystic type{the development of ameloblastomas in the wall of cysts : mural ameloblastomas) is less aggressive with dis­tinctly low recurrence rate , and (3) the rare peripheral extraosseous type. Although benign , ameloblastomas are nonencapsulated and locally invasive with a high recurrence rate unless adequate surgical resection is performed and maxillary ameloblastomas are inhe­rently more difficult to treat and are considered more aggressive than their conterparts in the mandible. The

* Unicystic ameloblastoma typical ameloblastoma begin insidiously as a central .. Enhancing solid component was larger than cystic component lesion of bone and is slowly destructive with a tendency in 9 patients. to bone expansion. However , the cortex may be eroded

various degree of inhomogenous enhancement was demonstrated in all cases including unicystic amelo­blastoma. In nine tumors, the enhancing solid portion was larger than cystic portion(Fig. 1 and 2). One maxil­lary ameloblastoma contained a thick calcification along the margin of the lesion(Fig. 3)

Resorption of the tooth root 'or displacement of the tooth was seen in five cases , which was demonstrated better on panoramic radiographs than on plain radio­graphs or CT. Bony septa were visualized as well on plain radiographs or panoramic radiographs as on CT in eight multilocular tumors. Extension of the tumor into the adjacent structures and its boundary with the normal tissue were well delineated on CT but not on

Table 1. CT Findings of Ameloblastoma in Mandible & Maxilla

Site Mandible Maxilla CTFindings (n=9) (n=2)

Size(cm) 3-14.5 3- 8 Locularity

Multi locular 8 o Unilocular 2

Type

Cystic 1* 0

Solid 0 0

Mixed 8 2 Cortical destruction

Focal 4 2 Extensive 3 0

Contrast enhancement 9** 2

」α19 Deok Kim, et al: Ameloblastoma of the Mandible and Maxilla

plain or panoramic radiogrphs. Three-dimensional-reconstruction images obtain­

ed in two patients well demonstrated extensive bulging and destruction of the mandible in one(Fig. 1) and in­tact cortex in the other.

DISCUSSION

a b

Fig. 2. 12-year-old boy. Postcontrast axial(a) and coronal CT scans show a large expansile, solid and cystic mass in the left mandible. The solid com­ponent within the mass is larger thancystic 。ne. Partial cortical destructions are pres­ent

떠 끽

Journal 01 the Korean Radiological Society 1995 : 33(3 ) : 351 - 356

a Fig. 3. 63-year-old male

b c

Axial(a) and coronal(b) postcontrast CT scans show a unilocular lesion with thick calcified wall occupying almost entire right maxillary antrum with an enhancing soft tissue mass at alveolar ridge , which protrudes from the antral cavity to the cheek via a cortical destruc­tion of the anteroinferior antral wal l. Histopathologic examination(c) reveals neoplastic epithelial islands exhibiting peripheral palisading and centrally located, loosely arranged stellate cells , and occasionally squamous metaplasia with keratin pearl(small ar­row) formation and dystrophic calcification(l arge arrow) within the epithelial islands

and thinned and finally disrupted. Marginal resection is necessary to reduce the rate of recurrence from re­sidual tumor. In addition , if extracortical extent is seen , an adequate margin of surrounding soft tissue must be resected since ameloblastomas can proliferate in soft tissues(5-6 , 12-13)

Plain radiographs show an expansile unilocular or multilocular Iytic lesion with a “ honeycomb or soap ­bubble" appearance and sharp scalloped peripheral border. Resorption or deviation of dental roots may be present. Occasionally , the crown of a tooth may be found in association with the tumor , but if calcifications are found radiographically , the lesion is probably not an ameloblastoma. When locules are smallerthan 1 cm in diameter , they tend to be numerous, resembling a honeycomb pattern . Larger locules tend to be fewer in number and show soap-bubble appearance. When the tumor is multilocular , the cystic portions commonly ap­pear 1 arger in the posterior part than in the anterior part of the mandible. On CT, ameloblastomas appear as an inhomogenous, multilocular or multiseptated soft tis­sue mass containing areas of low attenuation sepa­rated by curvilinear areas of intermediate or high at­tenuation. Plain radiograph , panoramic radiogrpah , conventional tomograph , and CT reveal shel l-l ike bu­Igings of the cortex or cortical destruction and allow de­termination of whether the tumors are m비tilocular or unilocular , but extension of the tumor into the adjacent structures are delineated more clearly on CT than on

radiographs. MR imaging is superior to plain ra­diographs and CT in demonstrating components of the tumor , features of the walis of cystic components , and the nature of cystic fluids but not in delineating cortical margins and soft tissue invasion. MR imaging is also useful in investigating the recurrence because MR imaging has the potential to allow distinction of recur­rent lesions from postoperative fibrosis by means of different signal intensity on T2 -weighted images. CT is more useful than MR imaging when a lesion is small and the cortical bone around the lesion is considered to be preserved at plain radiographs , while three­dimensional evaluation with MR imaging is more help­ful for surgical planning in the case of extensive in­vasion of the adjacent softtissue(4 -6, 14 -20).

In our study , ali mandibular ameloblastomas except one unicystic type(90%) were multilocular and ali ma­xillary tumors(100 %) were unilocular expansile les­ions. AII tumors except two small mandibular amelo­blastomas , less than than 5 cm in diameter , had corti­cal destruction and large locules. Extensive soft tissue invasion was seen in two recurrent and one primary mandibular ameloblastomas. AII cases demonstrated various degree of inhomogneous enhancement in solid portion on postcontrast CT and in 82% of them , solid portion was larger than cystic portion . Minami et al. (18) reported that 13 of 14 maxillomandibular ame­loblastomas showed strong enhancement of solid components on enhanced MR imaging and they th-

않

Jong Depk Kim, et al: Ameloblastoma of the Mandible and Maxilla

ought that hypervascularity of some ameloblastomas

could explain the marked gadolinium enhancement

An unusual finding in our study was seen in a 63

year - old man with a 28 - year - history of painless cheek

mass and in an oroantral fistula of8 - year-duration(Fig

3). A thick calcification was seen along the margin of

unilocular maxillary antral lesion in addition to soft tis­

sue mass formation around the cortical destruciton at

anteroinferior maxilla. This calcified lesion appeared

as a large air cavity and it seemed to arise from free en­

trance of the air through the oroantral fistula near the

cortical destruction , which developed after an extrac­

tion of maxillary second prem이 ar tooth 8 years pre­

viously. In the literature we could find only four cases of

maxillomandibular ameloblastomas with calcification , and the fi rst two of them were with only small amount of

dystrophic clacification , the second one with numerous

calcified keratin pearls , and the last one with a poorly

organized mass resembling cementum(21 -23). Kera­

tinization and dystrophic calcifications are also com­

monly seen in craniopharyngiomas , the pituitary cou­

nterpart of ameloblastoma of the jaw bones(21). In our

case it was dystrophic calcification

In conclusion , maxillomandibular ameloblastomas

appeared as expansile lesion containing enhancing

solid .component relatively larger than cystic portion

and having cortical destruction in large lesions(5 cm

>). Maxillary ameloblastomas were unilocular in ap­

pearance in spite of multilocularity in mandibular co­

unterparts.

REFERENCES

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2. Adekeye ED, Lavery KM : Recurrent ameloblastoma of the max­

illa-facial region. J MaxillofacSurg 1986; 14: 153-157

3. Seabaugh JL , Templer JW, Havey A: Ameloblastoma presenting

as a nasopharyngeal tumor. Oto/aryngol Head Neck Surg 1986;

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7. Batsakis JG , McClatchey KD: Ameloblastoma of the maxilla and

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532-533

8. Gardner DG , Pecak AMJ ‘ The treatment of ameloblastoma ba­

sed on pathologic and anatomical principles‘ Cancer 1980; 46

2514-2519

9. Gardner DG : A pathologist’s approach to the treatment of am­

eloblastoma. JOral MaxilofacSurg 1984; 42: 161-166

10. Bredenkamp JK , Zimmerman M‘ Mickel R: Maxillary amelo­

blastoma. ArchOto/aryngol Head NeckSurg1989; 115 ‘ 99-104

11. Scaccia FJ , Strauss M, Arnold J, Maniglia AJ:Maxillary Ame­

loblastoma : Case report. Am JOto/aryngo/1991 ; 12 : 20-25

12. Schteyer A , Lustmann J, Lewin-Epstein J. The mural amelo­

blastoma: a review of literature JOral Surg 1978; 36: 866

13. Tsakins PJ, Nelson JF: The maxillary ameloblastoma: an analy­

sis of 24 cases. J Oral Surg 1980; 38: 336-342

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tive study of magnetic resonance imaging versus computed tom­

。graphy for the evaluation of maxillary and mandibulartumors. J

Oral Maxillofac Surg 1988; 46: 1 039-1 047

15. Langlais RP. Radiology of the jaws. In Delbalso AM , eds. Ma­

xillofacial imaging. Philadelphia: Saunders , 1990; 343-373

16. Farman AG , Nortj CJ , Wood RE. Oral and maxillofacial diagnostic

imaging. St. Louis: Mosby , 1993; 239-279

17. Heffez L, Mafee MF, Vaiana J. The role of magnetic resonance

imaging in the diagnosis and management of ameloblastoma, OralSurg Oral MedOral patho/1988; 65: 2-12

18. Minami M, Kaneda T, Yamamoto H, et al. Ameloblastoma in the

maxillomandibular region : MR imaging. Radiology 1992; 184

389-393

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Journal of the Korean Radiological Society 1995; 33(3) : 351-356

대 한 방사 선 의 학회 지 1995; 33(3) : 351-356

상악골빛 하악골법랑아세포종의 CT 소견1

1 인제대학교의과대학부산 백병원 진단방사선과학교실

김 종 덕·최 재 영

목 적 :상악글과 하악글 법랑아세포종으I CT소견을 분석하여 그 특징을 알아보고 발생장소에 따른 차이점 유무를 살펴보

고자하였다.

대상 및 방법 :수술 및 조직소견으로 확진된 2예의 상악골 법랑아세포종과 9예의 하악콜 법랑아세포종(수술 후 재발된 2

예 포함)을 대상으로 하였으며， CT소견은 종앙의 위치， 크기， 다방성 혹은 단방성， 고형성 혹은 낭성， 조영증강앙상， 글피질

미란 및 파괴와주위 연조직 침습 여부를 후향적으로 분석하였다.

결 과:하악골 법랑아세포종 9여| 중 1 예으| 단일낭성종양(unicystic type)을 제외한 8여|에서 다방성의 팽창성 종괴로 나타

났고， 상악골 법랑아세포종 2예늠 둘다 단방성의 팽창성 종괴로 나타났다.11예 모두가 종앙의 고형성 부분에 불균등한 조영

증강을 나타내었으며 이중 9예에서는 이 부위가 낭성부분보다 컸다. 직경이 5cm 이상인 종앙 9여|에서 국소적 또는 광범위

한 글피질 파괴와 함께 다앙한 정도의 주위 연조직 침습을 나타내었다.1예의 상악콜 법랑아세포종에서는 종앙 주변부를 따

라 두터운 석회화가 나타났다.

결 론:하악글과 상악골 법랑아세포종은 모두 팽창성종괴로서 조영증강되는 고형성 부분이 낭성부분보다 더 크며， 골피

질의 파괴는 직경이 5cm 이상의 큰 종양에서 나타났다. 하악골과 상악골 법랑아세포종의 차이점으로는 전자는 다밤성， 후자

는 단방성 종괴임을 들 수 있었다.

따 씨