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provided by Elsevier - Publisher Connector Oral Oncology EXTRA (2006) 42, 287– 290

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CASE REPORT A case report of a hybrid odontogenic tumour: Ameloblastoma and adenomatoid odontogenic tumour in calcifying cystic odontogenic tumour

Weiping Zhang, Yu Chen *, Ning Geng, Dongmei Bao, Mingzhong Yang

Department of Oral Pathology, West China College of Stomatology, Sichuan University, No. 14, 3-section, Renminnan Road, Chengdu 610041, PR China

Received 23 May 2006; received in revised form 27 June 2006; accepted 7 July 2006

KEYWORDS Summary A hybrid odontogenic tumour comprising three distinct lesions is extremely rare. Ameloblastoma; We presented a hybrid odontogenic tumour composed of a calcifying cystic odontogenic tumour Adenomatoid odontogenic (CCOT), a solid multicystic ameloblastoma (A-S/M) and an adenomatoid odontogenic tumour tumour; (AOT). This tumour was observed in the anterior area of the mandible of a 64-year-old Chinese Calcifying odontogenic woman. Masses of ghost epithelial cells with the characteristics of CCOT were seen in the lining cyst of the cyst. The odontogenic epithelia with the features of A-S/M and AOT were also observed. c 2006 Elsevier Ltd. All rights reserved.

Introduction Case report

In the oral maxillofacial region, calcifying cystic odonto- On July 19, 2001, a 64-year-old woman was referred to the genic tumour (CCOT), solid multicystic ameloblastoma (A- West China College of Stomatology, Chengdu, China, for a S/M) and adenomatoid odontogenic tumour (AOT) are painless enlarging mass in the anterior of the mandible re- well-recognised whereas hybrid odontogenic tumours have gion with a history of 16 months duration. The patient sta- been rarely reported.1–17 The previously reported hybrid ted that the lesion had grown gradually in the past year. odontogenic tumours usually comprised two types of odon- The mass enlarged and paraesthesia appeared in the lower togenic tumours. However, no hybrid odontogenic tumour lip left side 20 days prior to the hospital visit. Physical with the definite components of CCOT, A-S/M and AOT examination revealed an obvious mass in the anterior of simultaneously in one lesion has been well-described in the mandible, with the size of about 3 · 3.5 · 1cm3. Part the English literatures so far. of the lesion was felt to fluctuate. Panoramic radiograph re- vealed a large intraosseous cystic lesion with multiple radi- * Corresponding author. Tel.: +86 28 85501465; fax: +86 28 opaque clusters and a well-demarcated border in the 85582167. E-mail addresses: [email protected], yourzhwp@yahoo. anterior of the mandible. The cyst extended from the left com.cn (Y. Chen). first molar region to the right second premolar region. An

1741-9409/$ - see front matter c 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.ooe.2006.07.003 288 W. Zhang et al. unerupted left lateral incisor was also detected in the cystic 1962.5 COC has been classified as calcifying cystic odonto- lesion (Fig. 1). A biopsy prior to surgery was done, and the genic tumour (CCOT) according to the most recently estab- histopathologic diagnosis was the CCOT. Under general lished histopathological criteria of the World Health anesthesia, an excision of the lesion was performed on the mandible left side via the interoral approach and the seg- mental resection of the mandible was performed from the left first molar region to the right first molar region. The right seventh and eighth ribs were taken to repair the man- dibular defect. The histopathologic diagnosis after the sur- gery is a hybrid odontogenic tumour characteristic of CCOT, A-S/M and AOT. No recurrence occurred during the post-surgical follow-up of three years. Histological examination revealed a hybrid odontogenic tumour, showing the histopathological characteristics of CCOT, A-S/M and AOT, which accounted for about 60%, 25% and 15% of the lesion, respectively. Nests of ghost epithelial cells were observed in the lining of ameloblasto- matous epithelium or in the fibrous capsule (Fig. 2a), sug- gesting the characteristics of CCOT. Deposits of scattered dentinoid or calcified materials were also noted. Further- more, follicular islands of odontogenic epithelium were detected within a fibrous stroma. The basal cells of some islands of odontogenic epithelium were columnar and hyper- chromatic, and were lined up in a Palisade fashion with re- versed polarity (Fig. 2b). The central cells were sometimes loosely arranged and resembled the stellate reticulum of the enamel organ, which fulfilled the ameloblastic histolog- ical criteria. Variably sized solid nodules of cuboidal or columnar cells of odontogenic epithelia in the form of ro- settes and duct-like structures were also observed in the connective tissue capsule of the cyst (Fig. 2c). In addition to forming ducts, the cuboidal or columnar cells formed con- voluted cords in a complicated pattern that often exhibited invaginations. Based on its diverse histopathological fea- tures, the pathological diagnosis of a hybrid odontogenic tumour composed of CCOT, A-S/M and AOT was made.

Discussion

Calcifying odontogenic cyst (COC) is an uncommon odonto- genic lesion, which was first described by Gorlin et al in

Figure 2 (a) Ghost cells of CCOT: pale, eosinophilic, and swollen ghost cells lost their nuclei but they showed a faint outline of the cellular and the nuclear membrane. (b) Follicular islands of odontogenic epithelium within a fibrous stroma, the central cells were sometimes loosely arranged and resembled the satellite reticulum of the enamel organ, basal cell is Figure 1 Panoramic radiograph revealing a large intraosseous hyperchromatism, vacuolisation and nuclear polarisation.- cystic lesion with multiple radiopaque clusters and an un- component of A-S/M. (c) Variable sizes of solid modules of erupted left lateral incisor in the anterior of the mandible. The cuboidal or columnar cells of odontogenic epithelia in the form cyst extended from the left first molar region to the right of rosettes and duct-like structures in the connective tissue second premolar region. The roots of the teeth covered by this capsule of the cyst - component of AOT (HE stain, original lesion were partially resorbed. magnification 200·). A case report of a hybrid odontogenic tumour 289

Organization (WHO).1 The microscopic feature of CCOT is China College of Stomatology, Sichuan University) and Dr characterised by the lining of a well-defined ameloblasto- Weihua Zhang (Department of civil engineering, Hongkong matous epithelium with variable amounts of ghost cells. University of science and technology) for their valuable ad- Several arguments have been proposed regarding the nature vice on the article writing. of ghost cells. Some studies18,19 suggested that the ghost cells might present the product of abortive enamel matrix References in odontogenic epithelium because enamel proteins were immunohistochemically expressed in the ghost cells. How- 3,15 1. Kleihues P, Sobin LH. Odontogenic tumours. In: Barnes L, ever, other studies indicated that the ghost cells repre- Eveson J, Reichart P, Siransky D, editors. World health sented different stages of normal and aberrant keratin organization classification of tumours. 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