Indian J Dent Adv 2012; 4(2) 843

Unicystic Ameloblastoma: A DiagnosticDilemma and Its Management Using Free

Fibula Graft: An Unusual Case ReportAniket Jain1, Satyajit Dandagi2, Amit Sangle3, Viquar Ahmed4, Akram Khan5

ABSTRACT:

A 20 year old patient reported with a swelling in the left posterior

mandibular region since 4 months. On clinical examination,

there was a hard, non-tender mass, measuring 8.5 cm by 5 cm

arising from the left side of the mandible, involving the ramus,

angle and body upto the leftt lower 1st premolar tooth.

Radiographic picture and fluid aspiration of the pathology with

protein analysis of 4.1 gm/dl, was suggestive of a keratinizing

cyst or tumor. Hemimandibulectomy was performed with safe

margins and an microvascular free fibula graft was placed for

mandibular reconstruction. The final diagnosis after

histopathological examination was given as Unicystic

Ameloblastoma. Facial Symmetry is well maintained with no

recurrence after a systematic follow up of 18 months.

Key words: Unicystic Ameloblastoma, Microvascular, Free

Fibula Flap

C A S E R E P O R T

doi: ...........................

1Final Year P.G Student2Professor3Professor4Senior Lecturer5First year P.G. Student

Department and Institution Dept of Oral andMaxillofacial Surgery, M A Rangoonwala College ofDental Sciences and Research Centre, Pune.

Article Info:

Received: April 15, 2012;Review Completed: May, 14, 2012;Accepted: June 13, 2012Published Online: August, 2012 (www. nacd. in)© NAD, 2012 - All rights reserved

Email for correspondence: draniketjain@gmail.com

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INTRODUCTION:

The most common tumour of odontogenic origin is ameloblastoma, which develops from epithelial cellularelements and dental tissues in their various phases of development. It is a slow-growing, persistent, andlocally aggressive neoplasm of epithelial origin.1 Unicystic ameloblastoma is second important clinical typeof ameloblastoma and accounts for 10-15% of all intraosseous ameloblastomas.2 They have been reported tooccur in second and third decades of life as against its solid counterpart which occurs in fourth decade of life.Unicystic ameloblastoma most commonly occurs in posterior mandible followed by parasymphysis region,anterior maxilla and posterior maxilla.3 It is a classic example of a true neoplasm of enamel organ typetissue that lacks the potential to undergo differentiation, and hence has aptly been defined as “unicentric,nonfunctional, intermittent in growth, anatomically benign and clinically persistent” by Robinson.There arethree forms of ameloblastomas, namely multicystic, peripheral, and unicystic tumors [4]. Multicysticameloblastoma is the most common variety and represents 86% of cases. Peripheral tumors are odontogenic

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Indian J Dent Adv 2012; 4(2) 844

tumors, with the histological characteristics ofintraosseous ameloblastoma that occur solely in thesoft tissues covering the tooth-bearing parts of thejaws. Unicystic tumors include those that have beenvariously referred to as mural ameloblastomas,luminal ameloblastomas, and ameloblastomasarising in dentigerous cysts [5]. It refers to thosecystic lesions that show clinical, radiographic orgross features of jaw cyst, but on histologicexamination shows typical ameloblastomatousepithelium, lining part of the cystic cavity with orwithout luminal and/or mural tumor growth.6 Wepresent a case of a large unicystic mandibularameloblastoma in a young male.

Case Report:

A 20-year-old female presented to Departmentof Oral and Maxillofacial Surgery with the Chiefcomplaint of painless swelling in left side of the facesince 4 months which was gradually increasing insize. Patient was apparently alright 4 months back,suddenly developed a small swelling in lower leftmandibular region which gradually increased in sizeto attain the present state.(Fig 1) There was noassociated pain, difficulty in opening the mouth,chewing or articulating. On physical examination,there was a hard, non-tender mass, measuring 8.5cm by 5 cm arising from the left side of the mandible,involving the ramus, angle and body upto the lefttlower 1st premolar tooth. Diffuse overgrowth seenin lower left posterior alveolar and vestibular regionwith normal overlying mucosa (Fig. 2). No necknodes were palpable. Systemic examination wasnormal. An Orthopantomogram (OPG) was done,which showed large cystic lesion in the left side ofmandible extending from lower left second premolarupto the ramus involving the condyle as well.Radiographic examination revealed a unilocularappearance and was suggestive of a cyst or tumour.(Fig 3 and 4) An aspirate of the fluid was obtained,and protein analysis revealed 4.1 gm/dl, which wassuggestive of a keratinizing cyst or tumor. Fineneedle aspiration cytology of the lesion as well asincisional biopsy was performed but both were notconclusive. Patient was taken up for surgery undergeneral anesthesia. Exposure of the lesion was donevia extended risdon’s incision followed byhemimandibulectomy along with dearticuation ofthe TM joint on the left side (Fig. 5 and 6).

Reconstruction was done using a microvascular freefibula graft. Shaping of the resected fibula was doneaccording to the preoperative template. A miniplatewith locking screws was used to secure theosteotomized fibula and the mandible (Fig. 7 and8). Final diagnosis of unicystic ameloblastoma wasconfirmed with the help of histopathologicexamination of the excised specimen (Fig. 9). Facialsymmetry was well maintained postoperatively. Oneyear systematic follow-up did not reveal anyrecurrence as well as showed excellent acceptanceof graft in the region mimicking a lower jaw. (Fig10 and 11)

Discussion:

Robinson and Martinez were the first personsto describe UA in 1977.7,8 It is most commonly seenin individuals who are 16 to 20 years of age.Occasionally, lesions occur in younger patients;rarely, they have been found in patients up to theage of 40.9 About 90% of the lesions are located inthe mandible and between 50 to 80% of these casesare associated with an impacted tooth.10,11 As seenin the present case, the unusual aspect is that itsnot associated with an imapacted tooth. Facialasymmetry due to swelling is the regular presentingfeature which infrequently relates with pain.

Unilocular ameloblastoma (UA) is a rare typeof ameloblastoma, accounting for about 6% ofameloblastomas. It refers to those cystic lesions thatshow clinical, radiographic or gross features of amandibular cyst, but on histologic examinationshows a typical ameloblastomatous epitheliumlining part of the cyst cavity, with or without luminaland/or mural tumor growth hence, UA should bedifferentiated from odontogenic cysts and alsoshould be recognized for the reason that the formerhas a higher rate of recurrence than the latter12.Ackermann et al have provided a histologicalsubgrouping of the Unicystic Ameloblastoma asshown in (Table 1) and a diagrammaticrepresentation of the same shown in (Fig. 12).2 TheUAs diagnosed as subgroups 1 and 1.2 can be treatedconservatively (careful enucleation), whereassubgroups 1.2.3 and 1.3 showing intramural growthsrequire treated radical resection, as for a solid ormulticystic ameloblastoma.13 Following enucleation,vigorous curettage of the bone should be avoided asit may implant foci of ameloblastoma more deeply

Unicystic Ameloblastoma Aniket Jain, et, al.

Indian J Dent Adv 2012; 4(2) 845

into bone. Chemical cauterization with Carnoy’ssolution is also advocated for subgroups 1 and 1.2.Subgroups 1.2.3 and 1.3 have a high risk forrecurrence, requiring more aggressive surgicalprocedures. This is because the cystic wall in thesecases has islands of ameloblastoma tumor cells andthere may be penetration into the surroundingcancellous bone.14,15

Recurrence is always an aspect to look afterresection specially in the case of unicysticameloblastoma. Lau et al reported recurrence ratesof 3.6% for resection, 30.5% for enucleation alone,16% for enucleation followed by Carnoy’s solutionapplication, and 18% by marsupialization followedby enucleation.16 Recurrence rates are also relatedto the histologic subtypes of UA, with those invadingthe fibrous wall having a rate of 35.7%, but othersonly 6.7%.15 Vascularised fibula graft was firstdescribed by Taylor in 1975, and in 1989 Hidalgofirst used free fibula flap in mandibularreconstruction.17 Later Chen and Yen incorporatedan overlying skin paddle for compositereconstruction of the bone and soft tissue defect.18

After demonstrating that osteotomies can beperformed in vascularised fibula grafts withoutcompromising the viability of the bone segment,vascularised free fibula flap became the state of artreconstruction method after mandible ablation.Normally if the tumour is small (< 5cm) the defectcan be repaired with a free bone graft. However,the tumour is often larger and a large defectreconstruction is challenging and may require amicrosurgical flap either from fibula, iliac crest,scapula, radius or ribs. Since this patient has a largebony defect, a free fibula osteoseptocutaneous flapwas chosen to address both the bony and soft tissuedefect.

Conclusion:

The diagnosis of unicystic ameloblastoma wasbased on clinical, radiological and histopathologicfeatures. Unicystic ameloblastoma is a tumor witha strong propensity for recurrence, hence thePathologist should examine the tissue sectionscarefully for better prognosis of the treatmentoutcome.

References:

1. Gerzenshtein J, Zhang F, Caplan J, Anand V, LineaweaverW: Immediate mandibular reconstruction with microsurgicalfibula flap transfer following wide resection forameloblastoma. J Craniofac Surg 2006;17(1):178-182.

2. Ackermann GL, Altini M, Shear M. The unicysticameloblastoma: A clinicopathologic study of 57 cases. J OralPathol 1988; 17: 541-546

3. Philipsen HP, Reichart PA. Unicystic ameloblastoma: areview of 193 cases from the literature. Oral Oncol 1998;34(5):317-325.

4. Philipsen HP, Reichart PA: Classification of odontogenictumors and allied lesions. Odontogenic tumors and alliedlesions Quintessence Pub. Co. Ltd 2004;21-23.

5. Chana, Jagdeep S, Yang-Ming Chang, Wei, Fu-Chan, Shen,Yu-Fen, Chan Chiu-Po, Lin Hsiu-Na, Tsai Chi-Ying, JengSeng-Feng: Segmental mandibulectomy and immediate freefibula osteoseptocutaneous flap reconstruction withendosteal implants: An ideal treatment method formandibular ameloblastoma. Plast Reconstr Surg 2004;113(1):80-87.

6. Philipsen HP, Reichart PA. Unicystic ameloblastoma. In:Odontogenic tumors and allied lesions. QuintessencePub.Co.Ltd, 2004; 77-86.

7. Srinivasan H, Arathy Manohar. Unicystic ameloblastoma ofthe mandible: A case report. Annals and Essence of Dentistry2010; 2(4):75-77.

8. Navarro CM, Principi SM, Massucato EM, Sposto MR.Maxillary unicystic ameloblastoma. Dentomaxillofac Radiol2004;33:60-62.

9. Sapp JP. Contemporary Oral and Maxillofacial Pathology(2nd ed) USA: Mosby 2004.

10. Philipsen HP, Reichart PA. Unicystic ameloblastoma.Odontogenic tumors and allied lesions. London: QuintessencePub. Co. Ltd 2004; 77-86.

11. Pizer ME, Page DG, Svirsky JA. Thirteen-year follow-up oflarge recurrent unicystic ameloblastoma of the mandible ina 15-year-old boy. J Oral Maxillofac Surg 2002; 60:211-215.

12. Ramesh Rakesh S, Manjunath Suraj, Ustad H Tanveer, etal. Unicystic ameloblatoma of the mandible-an unusual casereport and review of literature. Head and Neck Oncology2010; 2:1.

13. Philipsen HP, Reichart PA: Unicystic ameloblastoma.Odontogenic tumors and allied lesions London: QuintessencePub. Co. Ltd 2004; 77-86.

14. Li TJ, Kitano M, Arimura K, Sugihara K: Recurrence ofunicystic ameloblastoma: A case report and review of theliterature. Arch Pathol Lab Med 1998;122:371-374.

15. Li T, Wu Y, Yu S, Yu G: Clinicopathological features ofunicystic ameloblastoma with special reference to itsrecurrence. Zhonghua Kou Qiang Yi Xue Za Zhi 2002; 37:210-212.

16. Lau SL, Samman N: Recurrence related to treatmentmodalities of unicystic ameloblastoma: A systematic review.Int J Oral Maxillofac Surg 2006; 35:681-690

17. Taylor GI, Miller GD, Ham FJ. The free vascularized bonegraft: A clinical extension of microvascular techniques. PlastReconstr Surg 1975; 55(5): 533-544.

18. Chen ZW, Yan W. The study and clinical application of theosteocutaneous flap of fibula. Microsurgery 1983; 4(1): 11-16

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Indian J Dent Adv 2012; 4(2) 846

Table 1: Showing Akerman’s grouping of UA and their interpretation

Subgroup Interpretation

1 Luminal UA1.2 Luminal and Intraluminal UA

1.2.3 Luminal, Intraluminal and Intramural UA1.3 Luminal and Intramural UA

Figure 1: Facial Profile showing facialasymmetry on the left side

Figure 2: Diffuse overgrowth seen in lower leftposterior alveolar and vestibular region

Figure 3: OPG showing extent of lesion involvingbody, angle and ramus upto the condyle

Figure 4: Lateral view of body of mandibleshowing the extent of lesion

Figure 5: Exposure of the lesion via extendedrisdon’s incision

Figure 6: Resected specimen afterhemimandibulectomy

Figure 7: Retrieval and shaping of fibula graft withthe help of osteotomies and mini plates and screws

Figure 8: Post operative radiograph showing free fibulagraft secured at the recipient site with plates and screws

Figure 9: Histopathologic picture of the resected specimen showingtypical ameloblastomatous epithelium lining part of the cystic cavity

Figure 10: 18 months post operative radiographicpicture showing graft in place, mimicking the lower jaw

Figure 11: 18 months post operative intraoralview showing well adaptation of graft

Figure 12: Showing Ackerman’s grouping of UA asfollows: 1) Luminal, 2) Intraluminal, 3) Intramural

Unicystic Ameloblastoma Aniket Jain, et, al.