|Year : 2004 | Volume
| Issue : 2 | Page : 99-103
Calcifying odontogenic cyst
K Rajkumar1, K Kamal2, MR Sathish1, S Leena2
1 Department of Oral and Maxillo Facial Pathalogy, SRM Dental Colege & Hospital, Chennai, India
2 Department of Oral and Maxillo Facial Surgery, SRM Dental Colege & Hospital, Chennai, India
Department of OMFP, SRM Dental College and Hospital, Ramapuram, Chennai
Source of Support: None, Conflict of Interest: None
| Abstract|| |
The calcifying odontogenic cyst (COC) was first described as a separate entity by Gorlin in 1962. Once thought to be a cutaneous counterpart of benign calcifying epithelioma of Malherbe, described in 1980, COC is an unusual and unique lesion with characteristics of a solid neoplasm and of a cyst. It shows considerable amount of histopathological diversity, with variable clinical behaviour such as cystic, neoplastic, and infiltrating malignant behaviour. There may be variants of COC according to clinical, histopathological and radiological characteristics. Therefore a proper categorization of the cases is needed for better understanding of the pathogenesis of each variant. A case of calcifying odontogenic cyst is reported with a brief review of literature.
Keywords: COC, odontogenic cyst, odontogenic tumour
|How to cite this article:|
Rajkumar K, Kamal K, Sathish M R, Leena S. Calcifying odontogenic cyst. J Oral Maxillofac Pathol 2004;8:99-103
| Case Presentation|| |
An 11-year-old boy reported to the department of oral medicine and diagnosis. SRM Dental College with the chief complaint of an asymptomatic swelling of the left infra orbital region. The swelling has been present for two months and was slowly enlarging to a size of approximately 3 x 4 sq. cm . On evaluation an asymmetry involving the left mid - face. extending from the infraorbital rim to the angle of the mouth and anteroposteriorly from the left ala of the nose to about 3 cm in front of the tragus was present [Figure 1].
Palpation revealed a non-lender hard bony expansion of the left maxilla. Intra oral examination revealed buccal cortical expansion extending front 11 to 26 region. Obil- iterating the maxillary vestibule. The mucosa over the lesion was intact. On Palpation the Swelling was cystic and non-tender. Dental examination showed distal tipping of teeth 21, 22, retained teeth 63,65 and missing 23[Figure 2].
Radiographic examination showed a well defined multiocular radiolucency involving the periapices of I I to 25 dispersed with radiopaque structures (odontome like) within it [Figure 4]. It also revealed unerupted left maxillary permanent canine and displacement of the involved teeth. The maxillary occlusal view revealed buccal cortical expansion in relation to 6 3.24, 65 [Figure 3].
A differential diagnosis of dentigerous cyst. adenomatoid odontogenic tumour, calcifying odontogenic epithelial tumour and calcifying odontogenic cyst were considered based on clinical and radiological findings. An incisional biopsy of the cystic lesion was done whose histological evidence was consistent with that of COC. The lesion was enucleated following a complete medical examination.
The enuclealed specimen contained multiple cystic bags along with calcified dontome like structures [Figure 5].The entire specimen was sent for histopathological evaluation, which revealed a cystic lining composed of stratified squamous epithelium with ameloblastic type of basal cells containing hyperchromatic nuclei polarized away from the basement membrane [Figure 6]. Ghost cells, a consistent feature of COC were also evident within the loose spinous cell layer. Dystrophic calcification of ghost cells [Figure 7] and lining epithelium induced dentinoid matrix were found in the connective tissue wall. The decalcified sections of the hard tissue specimen showed dentin tissue made tip of dentinal tubules [Figure 8] A confirmatory diagnosis of COC was made based on the above findings. A one-year follow-up study was done in which the clinical and radiographic evaluation revealed no signs of recurrences.
| Discussion|| |
Gorlin and colleagues identified file COC as a distinct pathological entity in 1962. although according to Altini and Ferman  . The condition had previously been described in German literature in 1932 by Rywkind. It was earlier thought to be an oral presentation of cutareous calcifying epithelioma of Malherbe (1982) , . It was also termed as keratinising cyst and referred to a cyst by Chen & Miller  alt hough many solid lesion Were reported. In I963, Gold  found keratinization as a prominent feature and therefore renamed the lesion as keratinizing and calcifying odontogenic cyst (KCOC) , . Because of the Nailed histopathologic characteristics, various terminologies has been proposed which includes calcifying ghost cell odontogenic tumour (CGCOT) proposed by Fejerskov & Krogh in 1972: cystic calcifying odontogenic. tumour proposal by Freedman et al. (CCOT) in 1975.
The terms used for the solid neoplastic variant of COC were dentinogenic ghost cell tumour (DGCT) by Praetorius et al. epithelial odontogenic ghost cell tumor (EOGCT) by Ellis & Shmooklcr in 1986. odontogenic ghost cell tumour (OGCT) propsosed by Colmenero et al in 1990 and odontogenic ghost cell ameloblastoma by Shear  in 1994. The lesion accounts for 1% of all odotogenic jaw cysts  . The cystic or non neoplastic variant of COC is found to occur in 80-98%,ofcases  and associated with odontoma in 24% of cases , , The solid or neoplastic variant of COC accountcd to about 11.5% of cases  . The COC are usually intraosseous (70% of the cases)  with extraosseous presentation accounting for 16-22% , mostly seen in individuals above the age of 50 years.
The age ranges from 1 year to 82 years with peak in the 2 nd decade. In an observation of 215 lesions. Bruchner  and Praetorius et al  have drawn attention to bimodal age distribution in support of their contention that two difterent entities may be involved  with second peak in sixth / seventh decade , .
The lesion has no sex predilection and is equally distributed between maxilla and mandible  . COC are common anterior to the first molar region  in which 75% of cases are in the incisor canine region , or intercanine region usually crossing the midline in the mandible, which is a rare feature in the maxilla  .
The lesion is usually an asympiomatic swelling causing a hard bony expansion, rarely affecting the lingual surface of the law. The enlarging lesion can occasionally perforate the cortiical plate and commonly cause displacement of adjacent teeth or root tipping , with resorption of teeth adjacent to the lesion ,,, .
Central COC have been reported to be associated with an odontorma in 24% to 35% of cases , and with impacted teeth (35%). mostly canine , .
The histological featuresof a classic calcifying odontogenic cyst are characteristic and present few diagnostic problems. The microscopical feature of a classical COC includes a fibrous capsule with a lining of odonlogenic epithelium. The basal layer is made up of amelohlast-like columnar or cuboidal cells of 4-10 cell thickness ,, over lined by a loosely arranged epithelial cells hearing similarity to , stellatc recticulum of the enamel organ ,, . There exists varying number of epithelial cells devoid of nuclei. which are eosinophilic and retain their basic cell outline (ghost cells), These ghost cells may undergo calcification and lose their cellular outline to firm sheet like area, of calcified keratin ,, . Ghost cells may be due to the effect of coagulative necrosis and dystrophic calcification or it may be a form of normal or abnormal keratinization of the odontogenic epithelium. Ghost cells arc not unique to COC, but arc also seen in odontoma, meloblastoma, craniopharyngioma, and other odontogenic tumours , and can undergo calcification, which is believed to be dystrophic in nature ,, . The ability to induce dental hard tissue formation appears to be a property of epithelial cell lining of the COC ,, . In 1964. Seward & Duckworth , suggested the arrangement of areas of calcification within COC in layers parallel with the outline of the bony cavity, which provides a means of radiological differentiation from other calcifying odontogenic lesions and this type of linear calcification has been recorded in 40% of cases , . Occasionally ghost cells call evoke a foreign body reaction when they are present dose to the connective tissue. resulting due to the disintegration of the basal layer with subsequent in growth of granulation tissue and may undergo subsequent calcification.
Radiographically majority of the lesions present in an unilocular form ,, with well-defined margin , while in 5-13% of the cases they are multilocular. They have scattered irregular sized calcification producing a variable range of opacities [salt & pepper type of patterns , They may be associated with tooth like densities in 50% of the cases and one-third of the cases show association with unerupted tooth, most often a canine  .
COC in its earlier stages resembles dentigerous cyst, odontogenic keratocyst or unicystic ameloblastoma and in later phases resembles adenomatoid odontogenic tumour, partially mineralized odontonia, calcifying epithelial odontogenic tumour, ameloblastic fibroodontoma  . The extrasseous them of COC may resemble a gingival fibroma gingival cyst or peripheral giant cell granuloma ,, .
Locally aggressive lesions and even malignant degeneration have been reported ,, . These lesions appear histologically similar to benign lesion. b ut shows prominent mitotic activity. nuclear and cytoplasmic pleomorphism, necrosis and invasion of surrounding structures , .
The treatment of cystic lesion involves enucleanon with long-terns follow-up. Recurrence depend, on completeness of cyst removal. Prognosis is good for cystic COC and less certain for neoplastic COC , . The COC may be associated with other odontogenic tumours such as adenomatoid odontogenic tumour ameloblastic fibroodontoma amelobtastic fibroma and ameloblasloina ,, where the treatment and prognosis in such cases is based on the associated tumours , .
Recent reevaluation of cases was done by Piaetorious, Hjorting, Hansen. Gorlin, and Vteker  for classification of the COC by its range, variation and neoplastic potential  . They suggested that the lesion consists of 2 entities, a cystic form and a neoplastic form the review includes the classification of lesion into 3 cystic variants type I A (Simple unicyslic). type 1B (odontoma producing), type I C (aneloblastomatous prolilcratng) and a singly neoplastic type (type II) designated as dentinogenic ghost cell tumour.TheWorld Health Organization (WHO) recognized COC as a separate entity in 1971 ,[ 21] and currently classifies COC and all of its variants as odontogenic tumours rather than as odontogenic cysts  .
In 1991, a review of 92 cases of COC resulted in an alternative subclassification based on the histological and immunohistochemical features. The cystic lesion were classified , as:
1) Non proliferative COC
2) Proliferativc COC
4) COC associated with odontoma
The neoplastic lesion were classified as:
1) Ameloblastoma ex COC
2) Peripheral epithelial odontogenic ghost cell tumour , .
It 1994 according to studies by Wirshberg, Kaplan and Buchner, it was suggested that COC associated with an odortoma should be considered as a separate entity and classificd as benign mixed odontogenic tumour and termed as odontocalcifying odontogenic cyst  .
| Conclusion|| |
COC is a unique lesion possessing both cystic and neoplastic potential and showing considerable number of variants clinically radiographically, and histopathologically. Whether these variants represent unrelated lesions developing simultaneously or single lesion with ghost cell change is an open question and awaits further study. Separation of cases of dilicrcnt variants of COC may lead to a better understanding of each variant and may aid in its classification.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]