J Clin Periodontol 2002; 29: 83–86 Copyright C Munksgaard 2002Printed in Denmark . All rights reserved

ISSN 0303-6979

Case ReportGiovanna Orsini 1,Massimiliano Fioroni 2,Peripheral calcifying odontogenicCarrado Rubini 3 andAdriano Piattelli 4

1Dental School, University of Chieti, Italy;cyst2Dental School, University of Ancona, Italy;3Institute of Pathologic Anatomy andHistopathology, University of Ancona;4Department of Oral Medicine and Pathology,Dental School, University of Chieti, Italy; andEastman Dental Institute for Oral Health CareSciences, London, UK

Orsini G, Fioroni M, Rubini C, Piattelli A: Peripheral calcifying odontogenic cyst.J Clin Periodontol 2002; 29: 83–86. C Munksgaard, 2002.

AbstractBackground: Calcifying odontogenic cyst (COC) is a rare lesion representingabout 1% of jaw cysts. It may occur in a central (intraosseous) or peripheral (extra-osseous) location.Method: A case of peripheral COC located on the gingiva, appearing as a pain-less, circumscribed, pink nodule has been reported.Results: Peripheral, in contrast to central, COC tends to affect older patients.Peripheral COC is a less aggressive lesion than the central counterpart, and a

Key words: calcifying odontogenic cyst;simple excision biopsy is curative. gingival tumors; odontogenic tumorsConclusion: The histological finding of a keratinized epithelium rich in ghost cellshas helped in making the diagnosis. Accepted for publication 29 January 2001

Calcifying odontogenic cyst (COC) is acystic lesion in which the epithelial lin-ing shows a well-defined basal layer, anoverlying layer resembling stellate retic-ulum, and masses of ‘‘ghost’’ epithelialcells located in the epithelial cyst liningor in the fibrous capsule (Kramer et al.1992). COC represents about 1% of jawcysts (Lukinmaa et al. 1997, Toida et al.1990), and most cases are located an-terior to the 1st permanent molars (Od-ell & Morgan 1998). Central COC(CCOC) is found most commonly inthe 2nd decade of life (more than 40%of cases) (Cawson et al. 1998, Buchner1991, Buchner et al. 1990, 1991), whileperipheral COC (PCOC) affects indi-viduals most commonly in the 6th dec-ade (Odell & Morgan 1998, Shamaskinet al. 1989). 215 cases of CCOC and 45cases of PCOC have been reported inthe literature (Buchner 1991, Buchneret al. 1990, 1991). Shamaskin et al.(1989) have found, in an 18-year period,

5 PCOC out of 59,046 biopsy speci-mens.

COC is thought to represent a non-neoplastic lesion, but it has a potentialfor continuous growth (Cawson et al.1998). A lot of confusion and disagree-ment is present in the terminology andclassification of COC. Some investi-gators have considered COC as a tumorwith a tendency for marked cyst forma-tion. This concept, called ‘‘monistic’’ byToida (1998), has lead some researchersto substitute the terms ‘‘calcifying ghostcell odontogenic tumor’’ or ‘‘cystic cal-cifying odontogenic tumor’’ for that ofCOC. In addition, a ‘‘dualistic’’ ap-proach (Toida 1998) has been sug-gested, in that COC can contain 2 enti-ties: a cyst and a neoplasm. Indeed,Praetorius et al. (1981) divided COC in2 groups, cystic (1) and neoplastic (2),recognizing different histologic patternsin them: (1a) simple unicystic; (1b)odontome producing; (1c) ameloblas-

tomatous proliferating; (2) dentinogenicghost cell tumor.

The latter tumor may have an infil-trative growth pattern, is a predomi-nantly solid lesion with features ofameloblastoma, ghost cells and den-tinoid (Kramer et al. 1992). Other in-vestigators proposed for this neoplasticcounterpart the term ‘‘epithelial odon-togenic ghost cell tumor’’ and ‘‘odonto-genic ghost cell tumor’’.

Toida (1998) has recently suggested anew classification scheme based on thedualistic concept: (1) cyst: calcifyingghost cell odontogenic cyst; (2) neo-plasm – A. benign: calcifying ghost cellodontogenic tumor, (a) cystic, (b) solid;B. malignant: malignant calcifyingghost cell odontogenic tumor; (3) com-bined lesion: each of the categories de-scribed above associated with the fol-lowing lesions: (a) odontoma, (b)ameloblastoma, (c) other odontogeniclesions.

84 Orsini et al.

Fig. 1. Clinical aspect of the lesion at first presentation. Fig. 3. At low magnification, it is possible to observe the lining epi-thelium of the cyst and ghost cells (G). Hematoxylin-eosin ¿100.

Fig. 2. Periapical X-ray. An early resorption of the interproximal al- Fig. 4. At higher magnification, there are odontogenic epithelium is-veolar crest is present. lands surrounded by ghost cells. Hematoxylin-eosin ¿200.

Case report

A 39-year-old male patient with a non-contributory previous medical historypresented with a lesion of the attachedgingiva of the left lower molar region of1-month duration (Fig. 1). The lesionwas painless, firm and located in thearea between the 1st and 2nd molars. Apapule was located in the center of thelesion and had the appearance of adraining dental sinus tract. The 1st mo-lar had undergone endodontic treat-ment, and the 2nd molar was vital.There were no mobility, no purulentexudate and no periodontal defects oneither tooth. No fever, malaise orlymphadenopathy were present. A peri-apical X-ray showed that there was noerosion of the underlying bone or thepresence of radiolucences (Fig. 2).Under local anesthesia, the lesion wascompletely removed. Microscopic ex-amination showed a cyst lined by akeratinized epithelium with numerous

ghost cells (Fig. 3). At higher magnifi-cation, it was possible to observe foci ofodontogenic epithelium surrounded byghost cells (Fig. 4). The definitivemicroscopic diagnosis was calcifyingodontogenic cyst (COC). No recurrencewas present at a 5-year follow-up.

Discussion

Calcifying odontogenic cyst is usuallyasymptomatic, and often is an inciden-tal finding on radiographs (Cawson etal. 1998, Odell & Morgan 1998). 74 ofthe maxillary lesions affected the an-terior region as opposed to 56% of thelesions located in the mandible (Caw-son et al. 1998). Radiographically, thelesions appear as unilocular or multi-locular well-defined radiolucencies, andmay be associated with unerupted teeth(Cawson et al. 1998, Odell & Morgan1998). Peripheral COC has been re-ported to represent less than 25% ofcases (Odell & Morgan 1998). There is

also the possibility that PCOC is some-what more common, and that somecases of PCOC have been probablyclassified as other lesions, such as pe-ripheral ameloblastoma (Buchner 1991,Buchner et al. 1990, 1991). They areusually located on the gingiva or eden-tulous ridge; clinical appearance is thatof a painless, circumscribed, pink or rednodule, sometimes papillary (Cawson etal. 1998, Odell & Morgan 1998). Theswelling is usually located on the gin-giva or alveolar ridge, is smooth, with afirm or soft cystic texture, and is about0.5–1 cm in diameter (Cawson et al.1998). The incisor-canine or premolarregions of the mandible are most fre-quently involved (Cawson et al. 1998).About 55% of PCOC have been foundbetween the canines (Shamaskin et al.1989). In some cases (about 25%), thereis an erosion of the underlying alveolarbone (Cawson et al. 1998, Odell & Mor-gan 1998). About 30% of PCOC aresolid rather than cystic (against 2% of

Odontogenic cyst 85

CCOC), which can be related to theirsmall size (Buchner 1991, Buchner et al.1990, 1991, Odell & Morgan 1998).PCOC has a less aggressive behaviorthan the intraosseous counterpart(CCOC) and a simple excision biopsy iscurative (Buchner et al. 1991 Odell &Morgan 1998).

Microscopically, it is possible to findthe presence of thick-walled cysts thathave a smooth outer surface and asemisolid content (Odell & Morgan1998); usually there is a single cysticcavity or multiple smaller cavities (Caw-son et al. 1998). The cysts are lined byan epithelium, which is irregular instructure, variable in thickness and iscomposed of a columnar or cuboidallayer of preameloblast-like basal cellswith reversed polarity of their nuclei(Cawson et al. 1998, Odell & Morgan1998). The epithelial lining of COCsometimes has the capacity to inducethe formation of dental tissue in theconnective tissue wall, mainly in theform of odontomas (Shamaskin et al.1989, Buchner 1991, Buchner et al.1990, 1991). Indeed, COC can be foundin association with odontogenic tumorssuch as odontoameloblastoma, adeno-matoid odontogenic tumor, calcifyingepithelial odontogenic tumor, andameloblastoma (Lukinmaa et al. 1997,Toida et al. 1990, Buchner 1991, Buchn-er et al. 1991, Shamaskin et al. 1989,Takeda et al. 1990). The ghost cellsforming the suprabasal layers are largeand lightly eosinophilic, with a cyto-plasm containing diffuse tonofilaments,but not ortho- or parakeratin, andshowing a faint outline of the cellularand nuclear membrane (Cawson et al.1998, Van der Waal 1991). These ghostcells may form small foci within the epi-thelial lining or fuse into large masses,forming extensive sheets of an amor-phous, acellular eosinophilic material,extending or even filling the cyst lumen(Buchner 1991, Buchner et al. 1990,1991). Mineralization of the ghost cellsmay be seen (Buchner 1991, Buchner etal. 1990, 1991). They may also invadethe connective tissue, causing a foreignbody reaction (Cawson et al. 1998). Thepresence of ghost cells in COC is notpathognomonic, having been describedin ameloblastoma, ameloblastic fi-broma, ameloblastic fibro-odontoma,and odontomas (Odell & Morgan1998).

The microscopic differential diag-nosis must be made with peripheralameloblastoma. Like PCOC, peripheral

ameloblastoma also occurs at a signifi-cantly older age than its counterpart(Buchner et al. 1991). Both lesionsshare the presence of prominent elon-gated basal cells and stellate reticulumzone, but the presence of ghost cells israre in ameloblastoma (Odell & Mor-gan 1998). It is still very difficult to de-termine whether an individual lesionhaving a cystic architecture is truly cys-tic or neoplastic. Further studies, in-cluding immunohistochemical investi-gation on cell proliferation activity, mayhelp in resolving the question (Toida1998). Proliferating cell nuclear antigenlabelling index is a possible parameterfor differentiating benign from malig-nant COC, and, the proliferative fea-tures in the lining seem to be the mainfactor influencing the proliferating ac-tivity of COC (Takata et al. 1998).

Acknowledgments

This work was partially supported bygrants from the National ResearchCouncil (CNR), Rome, Italy; and bythe Ministry of University, Research,Science and Technology (MURST),Rome, Italy.

Zusammenfassung

Periphere kalzifizierende odontogene Zyste:Ein FallberichtHintergrund: Die kalzifizierende odontogeneZyste ist eine seltene Erkrankung, die etwa1% aller Kieferzysten ausmacht. Sie kann inzentralen (intraossar) oder peripheren (ex-traossar) Lokalisationen auftreten.Zielsetzung: Schilderung des Falles einer pe-ripheren an der Gingiva lokalisierten kalzi-fizierenden odontogenen Zyste, die alsschmerzloses, zirkumskriptes rosa Knotchenauftrat.Material und Methoden: Die periphere kalzi-fizierende odontogene Zyste wurde biopsiert.Da sich die periphere Variante weniger ag-gressiv als die Zentrale verhalt, ist die Exzi-sion bereits kurativ.Ergebnisse. In der Histologie fand sich einkeratinisierten Epithel, das reich an Geister-zellen war. Diese Beobachtung erleichtertedie Diagnosestellung.

Resume

Le kyste odontogenique calcifiant peripheri-que: rapport d’un casOrigine: Le kyste odontogenique calcifiant(COC) est une lesion rare representant envi-ron 1% des kystes de la machoire. Il peut sepresenter soit dans la partie centrale (intraos-seuse) soit dans la partie peripherique (ex-traosseuse).Methode: Un cas de COC peripherique loca-

lisee dans la gencive est apparu sous formed’un nodule rose circonscrit non-douloureux.Les COC peripheriques, contrairement auxcentraux, ont tendance a affecter les person-nes plus agees.Resultats: Le COC peripherique est une le-sion moins agressive que la centrale et unebiopsie d’excision simple permet de le soi-gner.Conclusion: La decouverte histologique d’unepithelium keratinise riche en cellules phan-tomes aide a etablir ce diagnostic.

References

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