Developing cementoblastoma: Case reportand update of differential diagnosisE. James Cundiff II, DDS, MSD'

The benign cementoblastoma is a rare odontogenic tumor that tends to occur in ihe jaws ot youngpeople. It is most commonly characterized as a circumscribed radiopaque mass attached to the toothroots and rimmed by a thin radiolucent zone. Early lesions, however, are radiolucent and can be confusedwith periapical conditions resulting from nonvitai teeth. The tumor is seldom recognized untii it producespain or expansion of the jaw. it the diagnosis is estabiished eariy, the tooth can be saved by endodontictreatment followed by apical root resection and surgical enudeation of the tumor This case reportdocuments the origin, development, and unlimited growth potential of a cementoblastoma. Radiographstai<9n at yearly intervais reveal an initial widening of the periodontal iigament space that grew into a 3-cmmixed radiolucent and radiopaque tumor over a 4-year period. The differential diagnosis and some criteriato help distinguish the cementoblastoma from similar-appearing lesions are reviewed. (Quintessence Int2000:31:191-195)

Key words: cementoblastoma, cdontcgenic neoplasm, periodontal iigament space, radiolucent lesion,radiopaque mass

The cetnentoblastotna is described by the WorldHealth Organization as a benign odontogenic

tumor composed of cementumlike tissue attached tothe tooth roots and appearing as a circumscribedradiopaque mass surrounded by a tiiin radiolucentline.' Odontogenic tumors account for P/o of biopsyspecimens received in oral pathology services, andcementoblastomas constitute only 1% of the odonto-genic tumors.^' Fewer than 75 cases have beenreported, and different reviews dispute some of these

Ulmansky et al* summarized the main features ofcementohlastoma in their review in 1994. Half of thepatients are younger than 20 years (49°k), and threequarters (73%) are younger than the age of 30 years.The majority (78%) of cementohlastomas arc found inthe mandible, and the most common site is themandibular first molar and premolar area. Themandibular and maxillary molar-prcmolar areastogether accounted for more than 90% of the cases.

Pain is a frequent finding (6P/o) and often imitatesa toothache. Swelling is a relatively constant finding,occurring in yo /o of the cases. In about 94% of cases,

'Associate Professor, Division of Oral Pathology, Baylor College ofOentistr/. Texas ASM uniuersity Health Soierce Cenler, Dallas, Texas.

Reprint requests: Di E. James Cundiff II, Associate Professor, Diuisjon ofOral Pathology, Baylor College of Dentistry, Tenas ASM University HealthScience Center, 3302 Gaston Avenue, Dallas, Texas 75246. Fax. 214-826-8306.

the radiograph revealed a radiopaque mass fused tothe roots and surrounded by a radiolucent halo.^

The tumor has unlimited growth potential.''^Treatment consists of removal of the tumor andattached tooth. The lesions are encapsulated, entjcle-ate easily from the surrounding bone, and do notrecur.' If the diagnosis is made while the tumor issmall, it can be surgically removed in conjunctionwith endodontic treatment and retention of theinvolved tooth.^

CASE REPORT

A 16-year-old white girl was referred to an oral sur-geon by her orthodontist for evaluation of a lesion ofthe right mandible. The orthodontist was able to pro-vide a series of annual panoramic radiographs datingback over the previous 4 years. The earliest pretreat-ment radiograph, taken when the patient was aged 12years, revealed the mandibular first molar to have asmall occlusal composite restoration and a normalapical area (Fig 1). Seven months later, there was aslight widening of the periodontal ligament space withmild sclerosis (Fig 2). These changes were more obvi-ous 1 year after the original radiograph (Fig 3).

At 2 years, the lesion appeared as an 8-mm scle-rotic area surrounded by a radiolucent zone (Fig 4).During the next year, the area became sensitive.

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Fig 1 A pretreatment radiograph, taken when thepatient was aged 12 years, re ieais no periapicallésion ot the mandibuiar nght firs! molar.

Fig 2 Seven months later, there is slight wideningof the periodontai ligament with miid sclerosis.

Fig 3 One year after the originai radiograph wasobtained, the changes appear more obvious.

Fig 4 At 2 years, there is an B-mm sclerotic area.surrounded by a radioluoent ;one.

Fig 5 At 3 years, the iesion has grown to 12 mm inwidth.

Fig 6 At 4 years, it has grown to a 3D-mm circum-scribed, mottled, radiopaque lesion nmmed by awide radioi jcent zone.

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Fig 7 (Isñ) The gross specimen reveáis acalcified mass surrounding the molar roots

Fig 8 (right) The specimen has been hemi-sected, revealing that the mass is fused tothe roots.

Fig 9 A photomiciograph of the root on the tight reveals thetumor proliferation from the cementum. The verticai void is an arti-factual tear. (Hematoxyiin and eosin stain, originai magnificationx40.)

Fig 10 Verticai trabeculae at the peiiphery are rimnied bycementobiasts and covered by a fibrous capsule. (Hematoxyiinand eosin stain; onginal magnification x100.)

An oral surgeon explored the area and referred her toan endodontist, who performed conservative endo-dontic treatment. At 3 years, the lesion had grown to12 mm in width (Fig 5). She continued to experiencesensitivity.

Fifteen months iater, 4 years after the first radio-graph was obtained, the orthodontist discovered theenlarged lesion on a routine posttreatment radiograph.The patient was referred to an oral surgeon, whofound expansion of the jaw. The radiograph revealed a30-mm, well-circumscribed, mottled, radiopaquelesion rimmed by a wide radiolucent zone of uniformwidth surrounding the roots of the mandibuiar rightfirst molar (Fig 6). The oral surgeon retracted amucoperiosteal flap and confirmed that the tumor hadexpanded the cortical bone. The bone was refiected toexpose a hard mass that separated easily from the sur-rounding bone. The tumor and first molar were enu-cleated and sent for pathologic examination.

Grossly, a circumscribed mass of calcified materia!,measuring 25 x 22 x 17 mm, surrounded the roots ofthe mandibular molar (Fig 7). The gross specimen wassurgically sectioned through its center; the hemisec-tion showed that the caicified mass was fused to thetooth roots (Fig 8).

The specimen was decalcified, and microscopicexamination revealed a neoplastic proliferation ofplump, spindled mesenchymal cells. Arising within thestroma were numerous trabeculae of calcified matrix.The neoplastic ceils showed no cytologie atypia ormitoses and were arranged either on the periphery ofcalcified trabeculae or centrally within lacunae of thematrix protein (Fig 9). The calcified trabeculae at theperiphery of the neoplasm were arranged at character-istic right angles to the surface and partially rimmed bya thin, fibrous tissue capsule (Fig 10), a feature highlycharacteristic of benign cementoblastoma. Therefore, adiagnosis of benign cementoblastoma was made.

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DISCUSSION

This is the first case report to demonstrate radiograph-ically the progression of a cementoblastoma at yearlyintervals, from its inception as a widening of the perio-dontal ligament space to its eventual status as a 30-mtn-diameter lesion surrounding the moiar roots. Thediscrepancy in size between the gross and the radio-graphic measurements is the result of normal distor-tion of panoramic images.

Most cases of cementoblastoma have been reportedat an advanced stage, suggesting that they either werenot diagnosed or were misdiagnosed earlier. Usuallythere is a history of pain, but the involved tooth is vitalin the absence of concomitant pathosis. The diagnosisis rarely made before significant bone expansion occurs.

Only a few reports have followed a tumor over anextended period.^"-'' Eversole et aP' were the first todescribe a cementoblastoma in the radiolucent stage,and only 2 subsequent cases have been reported atthis early stage."'^ Abrams and coworkers'" consid-ered the progression of a lesion from a radiolucent toa calcified state to he more consistent with a processof osseous dysplasia than with the development of theneoplasm, cementoblastoma.

The early presentation of this tooth, with wideningof the periodontal ligament space, suggested the pres-ence of traumatie occlusion. When the space contin-ued to widen and sclerosis developed in the adjacentbone, the most likely diagnosis would have been focalsclerosing osteomyelitis. This condition is the result ofpulpitis or pulpal necrosis and usually involves themandibular premolar or molar of young persons. Thecontinued progression and sensitivity were consistentwith osteomyelitis, except that vitality tests indicatedthat the tooth was vital.

If the leeth are vital and asymptomatic, a pulpalorigin can be excluded and other conditions should beconsidered. A similar-appearing lesion was recentlydescribed by Summerlin and Tomich" as focalcemento-osseous dysplasia (FCOD). They reportedthat FCOD appears as a fairly well-defined, localizedradioiucency with or without a sclerotic border or as amixed radiolucent and radiopaque lesion in closeassociation with the periapex or previous extractionsite. The posterior mandible is involved in 77% ofcases, and the lesion rarely causes expansion. It isfound most often in middle-aged women; about 88%of cases of FCOD occurs in females. Focal cemento-osseous dysplasia rarely affects young people; affectedpersons have a mean age of 37.8 years,

Summerlin and Tomich" considered FCOD to rep-resent a stage of the spectrum of dysplastic cemento-osseous proliferations that range from periapicalcemento-osseous dysplasia (cementoma) to florid

cemento-osseous dysplasia. Focal cemendysplasia cannot be distinguisbed radiographica ly tromthe early developing cementoblastoma, and bo'.ii wouldbe associated with vital teetb. The biopsy of ?COD willyield gritty hcmorrhagic fragments of tissue because thelesion is difficult to separate from the adjacent bone.Once the diagnosis of FCOD is established, mostpatients will remain stable, and no further treatment isindicated. One of the radiographs in Iheir article onFCOD'' showed a mandibular first rnolar with a lesionthat could easily be confused with a cementoblastoma.

Summerlin and Tomich" distinguished betweenFCOD and another condition that must be considered,in the differential diagnosis, the central cemento-ossi-fying fibroma (COF). The COF is another benign neo-plasm with the potential for unlimited growth. It isfound more often in young people (mean age of 29.9years). Expansion of the jaws and mild tenderness arefrequently noted. It usually appears as a well-demar-cated radioiucency; some may show fine, radiodensesnowñakes, while others show a sclerotic rim that fre-quently bows the inferior border of the mandible," Suet al'^ published an excellent review delineating COFand FCOD. They noted that the COF typically appearsas a well-defined radioiucency with or without a scle-rotic border. The radiograph of FCOD predominantlyreveals opacity or mixed lucency and opacity and anill-defined border. The majority of COFs are not asso-ciated with the apex of the tooth roots, but they oftencause divergence of the roots or displacement of theinvolved teeth. The histologie appearances of COFand FCOD are similar, but the gross specimens arequite different.' In contrast to FCOD, which separateswith difficulty, resulting in gritty bony fragments thecentral cemento-ossifying fihroma is a well circum-scribed tumor that can be enucleated.

One of the most frequently debated issues is the dif-ferentiation between ccmenfohlastoma and osteoblas-toma. Osteoblastomas occur in the same age groupand exhibit similar features. Many specialists in ortho-pedic pathology consider these to be identical lesions.Dorfman^" stated tbat the cementoblastoma is anosteoblastoma located in the jaws, in the vicinity ofthe roots of teeth, implying that cementoblastomas donot arise frorn odontogenic tissue. The jaws were thesecond most frequent site of Dorfman's cases, suggest-ing that a number of cementoblastomas had beenincluded with the osteoblastomas.

The osteoblastoma produces a round, well-demar-cated, lytic radiolucent nidus surrounded by a zone ofreactive sclerosis. Although grossly the osteoblastomais well demarcated, microscopically the osteoid trabec-ulae merge gradually with the adjacent normal bone;this is unlike the encapsulation encountered in cemen-toblastomas. Dorfman^" also conceded that those in

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the mandible have a different radiographie appear-ance: a central opacity surrounded by a lucent halo.

Osteoblastomas are not easily enucleated and areusually curetted as hemorrhagic gritty fragments. Thepreferred primary treatment for osteoblastomas is sur-gical en bloc excision, and there is a recurrence rate ashigh as 250/b; cementoblastomas do not recur.

Slootweg ' compared the histologie features of thecementoblastoma and the osteoblastoma and con-cluded that the appearance, including the peripheralspiculae rimmed by swollen blasts, was the same forhoth lesions. He emphasized that, although thesetumors occur at the same location and have the samehistologie appearance, they show different behavior.He heUeved that the cementoblastoma's fusion to thetooth justified its designation as a separate entity fromosteoblastoma- The World Heahh Organization's clas-sification of odontogenic tumors recognized the diffi-culties in distinguishing a cementoblastoma from anosteoblastoma based strictly on histologie appearance.'The cementoblastoma's distinct relationship with theroot of the tooth and the fact that it does not show atendency to recur were cited as justifications to sepa-rate the cementoblastoma from the osteoblastoma.'

The present case clearly shows the cementoblas-toma arising from the apical portion of the roots andgrowing over a 4-year period into the classic presenta-tion. The gross specimen revealed a symmetric calci-fied tumor surrounding the molar roots. There wasmicroscopic evidence of direct continuity between thecementum of the root and the tumor mass. The earli-est radiographie manifestation was widening of theperiodontal ligament space, conclusively demonstrat-ing an odontogenic origin for this neoplasm.

CONCLUSION

This case report presents the most convincing evi-dence published to date of the origin of the cemento-blastoma from the periodontal ligament and its unlim-ited growth potential. The lesion started as a wideningof the periodontal ligament space and proliferated toform a circumscribed, mottled radiopacity that grew to30 mm in diameter over a 4-year period. It appearedas a large, mixed radiolucent and radiopaque massthat engulfed the roots of the molar tooth and causedobviotis swelling of the jaw.

The differential diagnosis has heen described, andthe diagnostic procedures have heen discussed. Thisshotild alert clinicians to recognize this unique tumorat an early stage, when the tooth can be treatedendodontically and the lesion can he treated by con-servative surgical enucleation without loss of the tooth.

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