Vol. 98 No. 1 July 2004ORAL AND MAXILLOFACIAL PATHOLOGY Editor: Alan R. Gould

Hybrid odontogenic tumor of calcifying odontogenic cyst and

ameloblastic fibroma

Jung Hoon Yoon, DDS, PhD,a Hyung Jun Kim, DDS, PhD,b Jong In Yook, DDS, PhD,c

In Ho Cha, DDS, PhD,b Gary L. Ellis, DDS,d and Jin Kim, DDS, PhD,c Gwangju and Seoul,

Korea, and Salt Lake City, UtahCHOSUN UNIVERSITY, YONSEI UNIVERSITY COLLEGE OF DENTISTRY, AND ARUP LABORATORIES

Odontogenic tumors composed of 2 distinct types of lesions are unusual. We report an odontogenic tumor thatwas composed of calcifying odontogenic cyst and ameloblastic fibroma that occurred in the right posterior maxilla ofa 22-year-old Korean woman. The tumor had a cystic component with an ameloblastic epithelial lining andconglomerates of so-called ghost cells, and there were deposits of dentinoid material adjacent to the cyst. These arefeatures characteristic of calcifying odontogenic cyst. Enamel organ-like epithelial islands were observed within a dentalpapilla-like stroma of the cyst wall. Additionally, a solid portion of the tumor had characteristic features of ameloblasticfibroma, i.e., a myxoid cellular stroma with numerous elongated islands of ameloblastic epithelium. Ghost cell masseswere found in the area of ameloblastic fibroma as well. The distribution of the ghost cells suggests that this is a hybridlesion rather than a collision tumor. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004;98:80-4)Calcifying odontogenic cyst (COC), which was first

identified as an entity by Gorlin et al in 1962,1 has been

classified as an odontogenic tumor by the World Health

Organization.2 A variety of histopathologic features as

well as biologic behaviors have been described, and

several classifications have been proposed.3-5 Some

COCs appear to represent nonneoplastic cysts whereas

others have no cystic features and are regarded as

neoplastic.3,6 The characteristic microscopic features of

COC are a cystic epithelial lining with a well defined

basal layer of columnar cells and an overlying layer that

resembles stellate reticulum and masses of ghost cellsin the epithelial lining or in the cyst wall.2

aDepartment of Oral Pathology, College of Dentistry, Chosun

University.bDepartment of Oral & Maxillofacial Surgery, Oral Cancer Research

Institute, Yonsei University College of Dentistry.cDepartment of Oral Pathology, Oral Cancer Research Institute, Brain

Korea 21 Project for Medical Sciences, Yonsei University College of

Dentistry.dCenters of Excellence, ARUP Laboratories, Salt Lake City, Utah.

Received for publication Apr 7, 2003; returned for revision Jun 30,

2003; accepted for publication Jan 7, 2004.

1079-2104/$ - see front matter

2004 Elsevier Inc. All rights reserved.doi:10.1016/j.tripleo.2004.01.00380The additional characteristic finding is that COCs are

frequently associated with odontogenic tumors,3,6-10

a finding which is a rare event in other types of

odontogenic cysts or tumors. The most common of these

is odontoma,8 but, rarely, ameloblastoma, adenomatoid

odontogenic tumor, odontoameloblastoma, ameloblastic

fibroma, ameloblastic fibro-odontoma, and odontogenic

myxofibroma have been identified.3,6-14

In this article, a hybrid odontogenic tumor composed

of COC and ameloblastic fibroma of the right posterior

maxilla that occurred in a 22-year-old Korean woman is

described.

CASE REPORTA 22-year-old Korean woman visited the Department of

Oral & Maxillofacial Surgery at Yonsei University Dental

Hospital and complained of discomfort when chewing and

mobility of the right maxillary teeth for the last 3 months. The

patients medical history was noncontributory. There was

slight swelling of the right side of her face, but skin color was

normal. The maxillary right first and second molars were

displaced buccally, and there was a vestibular swelling and an

exudate from the gingival sulcus. Computerized tomograms

demonstrated a circumscribed, 3 cm in diameter, partially

cystic, intraosseous soft tissue lesion with multiple calcified

clusters (Fig 1). The presumptive clinical diagnosis was COC

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Volume 98, Number 1 Yoon et al 81OOOOE

Volume 98, Number 1 Yoon et al 81Fig 1. Computerized tomogram scan revealed a well defined intrabony cystic soft tissue lesion containing multiple radiopaque

clusters.

Fig 2. Photomicrograph of incisional biopsy specimen showing primitive dental papillaelike mesenchymal tissues admixed withproliferating odontogenic epithelium, resembling an ameloblastic fibroma (H-E, 3100).or ameloblastic fibro-odontoma. Incisional biopsy was

performed.

The biopsy specimen was composed of cellular, dental

papillaelike mesenchymal tissues admixed with numerouselongated, irregularly shaped nests of odontogenic epithelium

(Fig 2). The diagnosis was ameloblastic fibroma. However, the

radiographic finding of multiple calcified clusters within the

lesion raised a question as to whether the biopsy was

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82 Yoon et al July 2004Fig 3. A,Awell defined cystic lesion lined by an ameloblastoma-like odontogenic epithelium and large eosinophilic ghost cells withdeposits of dentinoid material (H-E, 340). B, The proliferating epithelial strands from the cyst lining and the associatedcondensations of cells within the stroma resemble primary ectomesenchymal induction of the dental lamina (H-E,3200). C, Ghost-cell clusters are present in islands of ameloblastic epithelium. These islands are situated in the myxoid stroma of the ameloblastic

fibroma component of the tumor (H-E, 3200).representative of the entire lesion. The lesion was excised under

general anesthesia. Postoperative course was uneventful, and

no recurrence was observed at a 1-year follow-up.

Grossly, the excised lesion was primarily cystic, but there

was a solid portion. Microscopically, the cystic portion had

conglomerates of ghost cells within an ameloblastoma-like

odontogenic epithelium. There were deposits of dentinoid

material adjacent to the epithelial lining (Fig 3, A). Enamelorgan-like epithelial islands were observed within the primitive

dental papillaelike mesenchymal tissue of the cyst wall, whichin focal areas was associated with a condensation of the stromal

cells (Fig 3, B). The solid portion of the lesion had a cellularmyxoid stroma with numerous islands of ameloblastic

epithelium, characteristic of ameloblastic fibroma. Ghost cell

masses were also found within ameloblastic epithelium in the

area of ameloblastic fibroma (Fig 3, C).

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Volume 98, Number 1 Yoon et al 83Fig 3. (continued).DISCUSSIONPraetorius et al3 classified the COC into 2 main

entities, a cyst and a neoplasm. The former presented

primarily as a unilocular lesion. Grossly, the lesion

described in this report was primarily cystic, but there

was a solid portion as well. The cystic portion was

typical of COC, and the solid portion was characteristic

of ameloblastic fibroma. Interestingly, a few islands of

ameloblastic epithelium in the ameloblastic fibroma

portion manifested ghost cell features.

The biologic mechanism causing such a unique com-

bination is not readily apparent. The possible pathogenic

mechanisms would seem to be either a collision of

2 separate lesions or a transformation of one lesion

to another. The collision of 2 separate tumors seems

unlikely in this case because both the COC and am-

eloblastic fibroma components exhibited ghost-cell

changes. It is more likely that this was a single neoplastic

process manifesting 2 distinct types of odontogenic

lesions. COCs have been associated with other odonto-

genic tumors, most frequently odontoma.3,4,6 It is not

fully understood whether those COCs secondarily

developed features of other odontogenic tumors3,7,10,15

or that the COC features were secondary phenomena in

pre-existing odontogenic tumors.16,17 However, several

investigators have suggested that proliferating odonto-

genic epithelial islands in COCmight induce the adjacent

mesenchymal tissue to develop features of other odonto-

genic tumors.3,7,9,10,15

In the current case, the proliferation of strands

of odontogenic epithelium from the cyst lining and

the associated condensation of cells within the stromaresembled primary ectomesenchymal induction of the

dental lamina. It can be speculated that the ameloblastic

fibroma in the lesion may have been induced by the epi-

thelium of the COC. Finally, the lesion may represent

divergent differentiation that the tumors may take,

depending upon the initial inductive stimulus and the

degree of odontogenesis prior to application of the sti-

mulus.9,10,15 Prognosis in this casewill probably be as ex-

pected for ameloblastic fibroma.

REFERENCES1. Gorlin RJ, Pindborg JJ, Clausen FP, Vickers RA. The calcifying

odontogenic cysta possible analogue to the cutaneous calcify-ing epithelioma of Malherbe. An analysis of fifteen cases. OralSurg Oral Med Oral Pathol Oral Radiol Endod 1962;15:1235-43.

2. Kramer IR, Pindborg JJ, Shear M. Calcifying odontogenic cyst.In: Kramer IR, Pindborg JJ, Shear M, editors. Histological typingof odontogenic tumours. 2nd ed. WHO International HistologicalClassification of Tumours. Berlin: Springer-Verlag; 1992. p. 20-1.

3. Praetorius F, Hjorting Hansen E, Gorlin RJ, Vickers RA.Calcifying odontogenic cyst. Range, variations and neoplasticpotential. Acta Odontol Scand 1981;39:227-40.

4. Hong SP, Ellis GL, Hartman KS. Calcifying odontogenic cyst. Areview of ninety-two caseswith reevaluation of their nature as cystsor neoplasms, the nature of ghost cells, and subclassification. OralSurg Oral Med Oral Pathol Oral Radiol Endod 1991;72:56-64.

5. Toida M. So-called calcifying odontogenic cyst: review anddiscussion on the terminology and classification. J Oral PatholMed 1998;27:49-52.

6. Waldron CA. Odontogenic cysts and tumors. In: Neville BW,Damm DD, Allen CM, Bouquot JE, editors. Oral & maxillofacialpathology. Philadelphia: Saunders; 1995. p. 506-9.

7. Shear M. Cysts of the jaws: recent advances. J Oral Pathol 1985;14:43-59.

8. Hirshberg A, Kaplan I, Buchner A. Calcifying odontogenic cystassociated with odontoma: a possible separate entity (odonto-calcifying odontogenic cyst). J Oral Maxillofac Surg 1994;52:555-8.

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84 Yoon et al July 20049. Farman AG, Smith SN, Nortje CJ, Grotepas FW. Calcifyingodontogenic cyst with ameloblastic fibro-odontome: one lesion ortwo? J Oral Pathol 1978;7:19-27.

10. Lukinmaa PL, Lepaniemi A, Hietanen J, Allemani G, Zardi L.Features of odontogenesis and expression of cytokeratins andtenascin-C in three cases of extraosseous and intraosseouscalcifying odontogenic cyst. J Oral Pathol Med 1997;26:265-72.

11. Freedman PD, Lumerman H, Gee JK. Calcifying odontogeniccyst. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1975;40:93-106.

12. Matsuzaka K, Inoue T, Nashimoto M, et al. A case of anameloblastic fibro-odontoma arising from a calcifying odonto-genic cyst. Bull Tokyo Dent Coll 2001;42:51-5.

13. Li TJ, Yu SF. Clinicopathologic spectrum of the so-calledcalcifying odontogenic cysts: a study of 21 intraosseous caseswith reconsideration of the terminology and classification. Am JSurg Pathol 2003;27:372-84.

14. Buchner A. The central (intraosseous) calcifying odontogeniccyst: an analysis of 215 cases. J Oral Maxillofac Surg 1991;49:330-9.15. Takeda Y, Suzuki A, Yamamoto H. Histopathologic study ofepithelial components in the connective tissue wall of uniloculartype of calcifying odontogenic cyst. J Oral Pathol Med 1990;19:108-13.

16. Tajima Y, Ohno J, Utsumi N. The dentinogenic ghost cell tumor.J Oral Pathol 1986;15:359-62.

17. Altini M, Farman AG. The calcifying odontogenic cyst. Eightnew cases and a review of the literature. Oral Surg Oral Med OralPathol Oral Radiol Endod 1975;40:751-9.

Reprint requests:

Jin Kim, DDS, PhD

Department of Oral Pathology

Oral Cancer Research Institute

Brain Korea 21 Project for Medical Sciences

Yonsei University College of Dentistry

Seodaemun-gu Shinchon-dong 134

Seoul 120-752, Korea

jink@yumc.yonsei.ac.kr

mailto:jink@yumc.yonsei.ac.kr

Hybrid odontogenic tumor of calcifying odontogenic cyst and ameloblastic fibromaCase reportDiscussionReferences