IJDA, 2(4), October-December, 2010 391

Plexiform Unicystic Ameloblastoma in a four year Old Child

Girish Rao1, Veerendra Kumar B2, Shyamala K3

Professor and head2

Lecturer3

Department of Oral & Maxillofacial PathologyDAPM. R. V. Dental College & Hospital,Bangalore, India

Email for correspondence:vinsanna@yahoo.com

Introduction:

Ameloblastoma is the most frequentlyencountered neoplasm derived from residualodontogenic epithelial components characterized bya benign but locally invasive behavior with a hightendency to recur. This tumor is most commonly seenin molar ramus area of the mandibular jaw bone ofindividuals in 3rd to 4th decade of life. The unicysticameloblastoma, a variant of ameloblastoma, hasbeen reported to occur in decade earlier than its solidcounterpart.1 There are less than 10% cases in theliterature where unicystic ameloblastoma has beenreported in very young children.2 Here is a case reportof one such rarity where plexiform unicysticameloblastoma showing mural proliferation, in anotherwise healthy four year old girl involving anteriorregion of the mandible.

Case report:

A four year old girl child presented with acomplaint of a slow growing swelling of the lowerjaw, front teeth region since the past eight months.Extra oral examination revealed mild, diffuse swellingon the right lower anterior portion of the mandible(Fig.1), which, on palpation was firm and non tender.Intra oral examination revealed a swelling extendingfrom 82 to 74. Expansion of both buccal and lingualcortical plates was evident (Fig.2). All laboratoryfindings were found to be within normal limits.Orthopantomography of the lesional area revealeda well defined unilocular radiolucency extendingfrom 82 to 75(Fig.3). The radiograph also showeddisplacement of the developing permanent teeth upto the inferior border of the mandibular jaw bone.Computed tomography showed an expansileosteolytic lesion (Fig.4). Incisional biopsy of the lesionwas performed and microscopic examination

Article InfoReceived: July 14, 2010Review Completed: August 16, 2010Accepted: September 12, 2010Available Online: October, 2010© NAD, 2010 - All rights reserved

CASE REPORT

ABSTRACT:

Unicystic Ameloblastoma, a variant of ameloblastoma has been

reported in the literature to be most commonly occurring

odontogenic tumor in the third decade of life. There are less than

10% of cases in the literature where unicystic ameloblastoma has

been reported in very young children. This odontogenic tumor is

also most commonly encountered in the posterior mandible in

association with an impacted tooth. Here is a report of a rare case

of plexiform unicystic ameloblastoma, in the anterior region of the

mandible of a four year old girl.

Key words: Unicystic Ameloblastoma, plexiform, odontogenictumors

Professor and HOD1

Department of Oral & Maxillofacial surgeryDAPM. R. V. Dental College & Hospital,Bangalore, India

INDIAN JOURNAL OF DENTAL ADVANCEMENTS

Jour nal homepage: www.nacd. in

IJDA, 2(4), October-December, 2010392

revealed odontogenic epithelial cells proliferating inbroad anastomosing cords showing presence ofperipheral tall columnar ameloblast like cells withreverse nuclear polarity and central stellate reticulumlike cells. There was also a focal area ofameloblastomatous cystic lining. Mature fibrousconnective tissue was seen between these epithelialcords. A diagnosis of plexiform unicysticameloblastoma was established. The tumor wassurgically resected along with the overlying teeth.Gross examination of the specimen revealed a wellcircumscribed tumor mass measuring about 4cm X5cm (Fig.5), firm in consistency the cut surface ofwhich showed a cystic sac, focal thickening of the cystwall and luminal nodules were also detected.Microscopic examination of excisional specimenrevealed a focal area of ameloblastomatous cysticlining and extensively invading strands ofodontogenic epithelium forming anastomosingnetwork, suggesting plexiform pattern into thesurrounding mature connective tissue (Fig.6 andFig.7). A diagnosis of plexiform unicysticameloblastoma grade III was reached. Post treatmentresponse of the patient is good.

Discussion:

Ameloblastoma is a benign odontogenic tumorarising either from rests of dental lamina, fromdeveloping enamel organ, from the epithelial liningof an odontogenic cyst or from basal cells of the oralectoderm. Its relative frequency equals the combinedfrequency of all other odontogenic tumors, excludingodontomas.3 Ameloblastomas are slow growing andlocally invasive tumors, occurring in three differentclinico-radiographic situations namely, Conventionalsolid/ multicystic, Unicystic and Peripheral.1

Unicystic Ameloblastoma is defined as a singlecystic cavity that shows ameloblastomatousdifferentiation in the lining. Solid masses of tumorcells may also extend into the lumen, or islands oftumor may infiltrate the fibrous wall. However to becategorized as unicystic, the ameloblastoma tissuemust be confined to the cyst and not extend into thewall.1

Ackerman et al, in their study of unicysticameloblastomas, defined three subgroups. Group I(42%) consisted of a unilocular cyst with anondescript but variable epithelial lining. Inactiveodontogenic cell rests might be present in the fibrouswall, but there was no infiltration by neoplasticepithelium. Group II lesions (9%) featuredintraluminal plexiform proliferation but no infiltrationof the cyst wall. In Group III lesions (49%), plexiformor follicular — type ameloblastoma, sometimes incontinuity with the cyst lining, infiltrated the wall.4

Group III lesions need to be treated more aggressivelysimilar to solid/multi cystic Ameloblastoma.1, 4

The present case shows presence of plexiformtype ameloblastoma in continuity with the cyst lininginfiltrating the wall and hence was diagnosed asgroup III plexiform unicystic ameloblastoma.

Ameloblastomas present over a wide age rangebut in industrialized countries they are usuallydiagnosed in the fourth and fifth decades of life. Indeveloping countries, ameloblastomas tend topresent about 10-15 years earlier.2

Several extensive surveys and reviews ofameloblastoma have been published, the mostnotable being those of Robinson in 1937 and Smalland Waldron in 1955. Analysis of more than 1,000cases by the latter authors revealed that theameloblastoma most commonly occurs in the 20 to49 years age, with average age at first diagnosis beingabout 39 years.5

A review of 1,036 ameloblastomas in which theaverage age is 38.9 years with only 2.2% under 10years of age and 8.7% between 10 and 19 years ofage.6 Similar were the results in a study by RA Ord etal 20027 and a study by Harvey P Kassler.8 Anobservation of these studies, suggests that onlyabout 10% of cases are reported to arise in children,and less than one third of those occur in childrenyounger than 10 years.2, 8

From various studies and published material weunderstand that Ameloblastoma is uncommon inchildren and that 80 to 90 % of the timesameloblastoma occurs in 3rd to 5th decade of life andonly 10% of the times it is reported in children of

Plexiform Unicystic Ameloblastoma in a four year Old Child Girish Rao, et, al.

IJDA, 2(4), October-December, 2010 393

around 10 years or lesser age. Various literature alsohave shown that about 80% of tumors occur inmandible, of which, 70% arise in the molar region andascending ramus, 20% in the premolar region, exceptfor desmoplastic ameloblastoma which occurs mostcommonly in anterior region of maxilla.2

Ackerman et al, in a study of 57 unicysticameloblastomas, concluded that the gender and sitedistribution corresponded with that of solid andmulticystic ameloblastomas, but the mean age atdiagnosis of 23.8 years was significantly younger.4

Shteyer et al found that unicystic ameloblastomaaffected younger age group, the average age being10.8 years.9 Gardener and Corio in their analysis of46 plexiform unicystic ameloblastomas alsoconcluded that they were more frequent in patientsless than 30 years old.10 Oliveiro et al, Wassermann etal, Qureshi et al have reported cases each of unicysticameloblastoma in patients with ages 5 years and 10years respectively.11,12,13

The present case report, of a four year old girlwith unicystic ameloblastoma with extensiveplexiform mural proliferation, occurring inmandibular anterior region, is rare and unique in itsage of occurrence and site. This case adds to the veryfew cases reported in literature, where plexiformunicystic ameloblastoma with extensive muralproliferation histopathologically and reaching a sizeof 4cm X5cm as evidenced clinically andradiographically in just a 4 year old child.

Conclusion:

Ameloblastomas remain an enigmatic group oforal tumors. This rare case of plexiform unicysticameloblastoma in four year old girl in anterior regionof mandible adds to the pediatric cases in literature.More such cases should provide us an insight to thebiologic behavior and clinical course of this tumorwhich may help in effective treatment plan.

References:

1. Roderick A Cawson at.al. Lucas’s Pathology of tumors ofthe Oral tissues. 5th Edition. Odontogenic tumors. Pg. No.25.

2. J. V. Soames, J. C. Southam; Oral Pathology, fourth edition.Odontomes and odontogenic tumors. Pg. No. 228

3. Neville BW, Damm DD, Allen CM, Bouquot JE: Oral &Maxillofacial Pathology, Third Edition, Pg. No. 702.

4. Ackermann GL, Altini M, Shear M. the unicysticameloblastoma: a clinico pathologic study of 57 cases. J.Oral pathol 1988;17: 541-546

5. Gorlin et. Al: Odontogenic Tumors. Cancer, jan —Feb 1961;vol 14, No.1 73- 98.

6. Small IA, Waldron CA: Ameloblastoma of the jaws. Oral surgoral Med Oral Pathol 8:281,1955.

7. Ord RA, Blanchaert RH, Jr, Nikitakis NG and Sauk JJ:Ameloblastoma in children. J Oral maxillofac Surg 60: 762-770,2002.

8. Kessler HP: Intraosseous ameloblastoma. Oral MaxillofacialSurg Clin N Am,16(2004); 309-322.

9. Shteyer A, Lustmann J, Lewis- Epstein J. The muralameloblastoma: A review of the literature. J Oral Surg1978;26:866-872.

10. Gardner DG, Corio RL. Plexiform unicystic ameloblastoma:a variant of ameloblastoma with a low recurrence rate afterenucleation. Cancer 1984;53:1730-1735

11. Oliveiro- Neto HH, Spindula- Filho JV, Dallara MC, Silva CM,Mendonca EF, Batista AC. Unicystic ameloblastoma in achild: a differential diagnosis from the dentigerous cyst andthe inflammatory follicular cyst. J Dent Child(Chic). 2007Sep-Dec:74(3):245-249.

12. Wassermann V, Huisman TA. Cystic ameloblastoma in a 5year old boy. Pediatr Radiol. 2008Apr; 38(4):482.

13. Qureshi SS, Medhi SS, Kane SV. Unicystic Ameloblastomaof the mandible masquerading as carcinoma of the oralcavity in a 10-year-old girl.

Fig.1. Swelling on the lower jaw front region

Plexiform Unicystic Ameloblastoma in a four year Old Child Girish Rao, et, al.

IJDA, 2(4), October-December, 2010394

Fig.2. Buccal and lingual cortical expansion seen intra orally Fig. 3: Orthopantomography showing well defined unilocularradiolucency with displacement of the developing Permanent teeth

Fig. 4: Computed tomography showing an expansile osteolytic lesion Fig. 5. Swelling on the lower jaw front region

Fig. 6: Low power photomicrograph showing unicystic odontogenicepithelial lining along with an area of transition in to a more proliferativeepithelium.

Fig.7: Photomicrograph showing Mural proliferation with anastomosingnetwork of odontogenic epithelium within connective tissue stroma.

Plexiform Unicystic Ameloblastoma in a four year Old Child Girish Rao, et, al.