Calcifying odontogenic cyst associated with compound odontoma – A rare entity

BK Akshatha; GS Manjunath; N Soundarya

doi:10.4103/jomfp.jomfp_411_22



CASE REPORT

Year : 2023 \| Volume : 27 \| Issue : 5 \| Page : 69-74

Calcifying odontogenic cyst associated with compound odontoma – A rare entity

BK Akshatha¹, GS Manjunath², N Soundarya³
¹ Assistant Professor, Oral and Maxillofacial Pathology and Microbiology, M. R. Ambedkar Dental College and Hospital, Bangalore, India
² Associate Professor, Oral and Maxillofacial Surgery, M. R. Ambedkar Dental College and Hospital, Bangalore, India
³ Professor and HOD, Oral and Maxillofacial Pathology and Microbiology, M. R. Ambedkar Dental College and Hospital, Bangalore, Karnataka, India

Date of Submission	30-Sep-2022
Date of Decision	10-Jan-2023
Date of Acceptance	11-Jan-2023
Date of Web Publication	04-Feb-2023

Correspondence Address:
B K Akshatha
M. R. Ambedkar Dental College and Hospital, 1/36, Cline Road, Cooke Town, Bangalore - 560 005, Karnataka
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jomfp.jomfp_411_22

Abstract

Calcifying odontogenic cyst (COC) or Gorlin's cyst categorized as a distinct entity by Gorlin et al. in 1962. It is a rare benign developmental cystic lesion that accounts for less than 1% of all odontogenic cysts. It can occur in association with various types of odontogenic tumors such as odontomas. COC is a hybrid lesion of the jaw presenting a manifold variety of clinical behaviors and histopathological characteristics including cystic, solid (neoplastic), and aggressive forms. COC exhibits diversity in terms of its clinical presentations, histopathologic features, and biological behavior. Normally, it presents as asymptomatic, slow developing lesion affecting the maxilla and mandible equally with strong predilection for the anterior segment. Radiographically, these lesions usually present as a unilocular, well-defined radiolucency with radiopaque structures within the lesion, either as irregular calcifications or tooth-like densities. The distinct features of COC as solid or cystic lesions presents with an ameloblastomous component admixed with varying proportions of ghost cells and spherical calcifications. Here, we report an article of calcifying odontogenic cyst associated with compound odontoma in a young patient with lesion in the anterior mandible with review of the various terminologies and classification and histopathology.

Keywords: Calcifying odontogenic cyst, compound odontoma, dentinoid, ghost cell, odontogenic cyst

How to cite this article:
Akshatha B K, Manjunath G S, Soundarya N. Calcifying odontogenic cyst associated with compound odontoma – A rare entity. J Oral Maxillofac Pathol 2023;27, Suppl S1:69-74

How to cite this URL:
Akshatha B K, Manjunath G S, Soundarya N. Calcifying odontogenic cyst associated with compound odontoma – A rare entity. J Oral Maxillofac Pathol [serial online] 2023 [cited 2023 Mar 21];27, Suppl S1:69-74. Available from: https://www.jomfp.in/text.asp?2023/27/5/69/369180

Introduction

True bone cysts are frequently encountered in facial bones due to the presence of embryonic epithelial rests in these bones. A majority of them are remnants of odontogenic apparatus.^[1] These odontogenic cysts are classified as either developmental or inflammatory in origin.^[2] Calcifying odontogenic cyst (COC) is a developmental odontogenic cyst and its occurrence constitutes about 0.3-0.8% of all odontogenic cysts.^[3] It was thoroughly described for the first time by Gorlin and co-workers in 1962 who were impressed by the significant presence of the so called “ghost cells.” Later, they suggested that this cyst may represent the oral counterpart of the dermal calcifying epithelioma of Malherbe. In 1963, Gold introduced the term keratinizing and calcifying odontogenic cyst.^[4] In 1971, COC was included by WHO in its classification of “Histological typing of odontogenic tumors, jaw cysts, and allied lesions.”^[5] It was further classified in 1992 and 2005 by WHO in odontogenic tumors. In latest classification in 2017, COC was classified among the developmental cysts.^[5] In addition, the cystic type of COC may be associated with other odontogenic tumors such as Odontoma, Adenomatoid Odontogenic Tumor, Ameloblastoma, Ameloblastic Fibro-Odontoma and Ameloblastic Fibroma COC may also be associated with impacted teeth.^[3] Clinically, it is characterized by slow growing painless swelling. It may have a central (Intraosseous) or less frequently a peripheral (Extraosseous) localization, causing lingual expansion, displacement of teeth, root resorption, and perforation of the cortical bone.^[6] Radiographic appearance shows unilocular radiolucency with possible radio opacities within the lesion. An important radiographic feature is the presence of calcification ranging from tiny flecks to large masses. The distinct feature of COC is a cystic lining demonstrating “ghost” epithelial cells with a propensity to calcify. This cyst most commonly occurs as a well-defined cystic lesion with fibrous capsule and a lining of odontogenic epithelium with ameloblastomatous appearance.^[7] Areas of eosinophilic matrix material, considered to represent dentinoid, sowing to the inductive effect may be present adjacent to the epithelial component.^[8] The simultaneous occurrence of COC with compound odontoma is uncommon. The purpose of this article is to present a rare case of COC associated with compound odontoma focusing on clinical, radiological, and histological findings with review of the literature.

Case Report

A 21-year old male patient reported to our centre with a chief complaint of a painless swelling of 2 to 3 months duration in the lower anterior tooth region. His medical and family history was unremarkable with no history of pain or trauma. On extra-oral examination a diffuse non-tender swelling was seen in the symphysis region. Intra-oral examination revealed vestibular expansion extending from 35 to 45 region. The overlying mucosa was normal in color. On aspiration straw colored fluid was obtained. Panaromic radiograph showed large well-demarcated unilocular radiolucency with multiple radiopaque locules within the lesion in mandibular anterior region extending from 35-45 region [Figure 1]. Root resorption was noted in relation to 45-32 in angular pattern. A cone beam computed tomography (CBCT) revealed large well-demarcated lytic lesion seen in mandibular anterior region extending from 35 to 45 region with multiple radiopaque locules within the lesion. Disordered tooth-like structures resembling multiple odontomas seen in 31, 33, and 34 region. Lytic areas expand bucco-lingually, superior-inferiorly from crestal region to lower border of mandible and medio-laterally from 35 to 45 region. Well-demarcated lytic lesion with homogeneous hypodense area with cortical plate expansion with thinning of lingual cortical plate seen. CBCT scan also confirmed root resorption of few teeth [Figure 2]. Radiographical differential diagnosis of CEOT, Ameloblastic Fibro-Odontoma was given. The chosen clinical conduct was surgical enucleation of the lesion. A crevicular incision was given from 35-45 teeth region in the alveolar ridge with mucoperiosteal flap detachment to facilitate access of the lesion. During surgery, the lesion was completely detached exposing mandibular bone which showed anterior bony erosion with eroded area measuring 1.5 cm × 1.5 cm in size allowing visualization of cystic lining [Figure 3]. Hence, enucleation was done along with complete removal of multiple tooth-like structures. Finally, flap was closed using 3-0 vicryl sutures. The gross findings were that of a ruptured cyst specimen measuring about 8 × 4 cm which was brownish black with an empty lumen along with multiple tooth-like structures [Figure 4]. Soft tissue specimen was sectioned into two halves with one half being processed and single tooth-like specimen was decalcified and sent for further microscopic examination. The histopathologic findings of soft tissue revealed basal cells of odontogenic cyst epithelial lining were mainly columnar similar to ameloblasts and the overlying layers were loosely arranged resembling stellate reticulum of enamel organ with presence of ghost cells within the epithelial component [Figure 5]. These eosinophilic ghost cells are altered epithelial cells that are characterized by loss of nuclei with preservation of the basic cell outline [Figure 6]. Areas of an eosinophilic matrix material that are considered dysplastic dentin (dentinoid) are present adjacent to epithelial component [Figure 7]. Based on these findings diagnosis of calcifying odontogenic cyst (COC) was made. Whereas histopathologic examination of hard tissue revealed presence of demineralized dentin surrounding the pulpal tissue suggestive of compound odontoma [Figure 8].

Figure 1: OPG shows large well-demarcated unilocular radiolucency with multiple radiopaque locules within the lesion in mandibular anterior region extending from 35-45 region

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Figure 2: A cone beam computed tomography (CBCT) revealed large well-demarcated lytic lesion seen in mandibular anterior region extending from 35 to 45 region with multiple radiopaque locules within the lesion. Disordered tooth-like structures resembling multiple odontomas seen in 31, 33, and 34 region

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Figure 3: The lesion was completely detached exposing mandibular bone which showed anterior bony erosion with eroded area measuring 1.5 cm × 1.5 cm in size allowing visualization of cystic lining

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Figure 4: The gross findings were that of a ruptured cyst specimen measuring about 8 × 4 cm which was brownish black with an empty lumen along with multiple tooth-like structures

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Figure 5: Scanner view (4X) revealed basal cells of odontogenic cyst epithelial lining were mainly columnar similar to ameloblasts and the overlying layers were loosely arranged resembling stellate reticulum of enamel organ with presence of ghost cells within the epithelial component

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Figure 6: Low power magnification (10X) demonstrates eosinophilic ghost cells which are altered epithelial cells that are characterized by loss of nuclei with preservation of the basic cell outline

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Figure 7: Areas of an eosinophilic matrix material that are considered dysplastic dentin (dentinoid) is present adjacent to epithelial component

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Figure 8: Low power magnification (10X) of hard tissue revealed presence of demineralized dentin surrounding the pulpal tissue

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Discussion

Epithelial lined cysts rarely occur in skeletal bones, as embryonic epithelial rests are normally not found in them. They do, however, occur in the jaws where the majority is lined by epithelium derived from remnants of the odontogenic apparatus. These odontogenic cysts are classified as either developmental or inflammatory in origin. The calcifying odontogenic cyst (COC) is a rare example of a developmental odontogenic cyst.^[9] The COC is a rare entity of uncertain pathogenesis. Its clinical and radiographic features are not pathognomonic, being characterized mainly by its histopathologic characteristics.^[7] Gorlin and colleagues identified COC as a distinct pathology entity in 1962 although according to Altini and Farman, a similar occurring condition had previously been mentioned in German literature in 1932 by Rykwind. It was earlier thought to be an oral presentation of dermal calcifying epithelioma of malherbe.^[10]

WHO in 1971 described calcifying ghost cell odontogenic Cyst (CGCOC) as a “non-neoplastic cystic lesion.” Nevertheless, it was decided that the lesion should be categorized as a benign odontogenic tumor. WHO classified CGCOC in 1992 as a neoplasm rather than a cyst but confirmed most of the cases are non-neoplastic. In view of this duality, many different terminologies have been applied to cystic and solid CGCOC variants, but the most preferred term is calcifying odontogenic cyst.

Different terminologies for COC are reviewed in [Table 1].^[4]

Table 1: Commonly used terminologies of COC are

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The first classification was proposed by Praetorius et al. (1981) as

Type I—(cystic type)

Type II—(neoplastic type [DGCT])

He further subdivided the cystic variant (Type I) into 3 different types which is as follows:

Simple—unicystic type.
Odontoma—producing type.
Ameloblastomatous proliferating type.

In 1992, WHO classified the cystic COC as non-neoplastic variant and DGCT as solid neoplastic variant which could show an infiltrative growth pattern.^[8]

Toida (1998) classified cystic variant of COC as calcifying ghost cell odontogenic cyst (CGCOC) and neoplastic variant of COC as calcifying ghost cell odontogenic tumor (CGCOT) as mentioned below:

Cyst: CGCOC
Neoplasm:

Benign—CGCOT

Cystic variant—Cystic CGCOT.
Solid variant—Solid CGCOT.

Malignant—Malignant CGCOT

Combined lesion:

Odontoma
Ameloblastoma
Other odontogenic lesions.

Based on histological behavior, COC was reclassified in 2005 by the WHO as CCOT for cystic type and dentinogenic ghost cell tumor (DGCT) for solid type. In the recent classification by the WHO 2017, the cystic forms were categorized under developmental cysts and solid forms were retained as mixed odontogenic neoplasms.^[19]

Praetorius et al.[20] suggested that COC develops in the dental follicle, gingival tissue or bone from remnants of either odontogenic epithelium or reduced enamel epithelium.^[3] The age of the patients may range from 5 to 92 years with peak incidence in the second and sixth decade of life with prevalence of 11.4% among Indian population.^[11],[12] In present case, it is seen in the third decade of life. Buchner found an almost equal gender distribution.^[3] COC accompanied by odontoma, the neoplastic type may occur in young patients with the mean age of 17 years.^[13] 65% of all cases of COC are reported in the anterior region of the mandible.^[7] COC clinically appears as a painless slow growing mass, equally affecting the maxilla and mandible with a predilection for the anterior tooth region. Radiographically, COC appears as a well-circumscribed unilocular or rarely, multilocular radiolucent lesion of different shape, size and opacity level.^[14] During early development of COC their development, they will appear completely radiolucent as they mature, calcifications will form that produce a well-circumscribed, mixed radiolucent-radiopaque appearance. Three general patterns of radiopacity are seen. First in form of flecks in salt and pepper pattern, second is a complete fluffy cloud-like pattern and third is a crescent—shaped pattern on one side of the radiolucency in a “new moon”-like configuration.^[15] Impacted teeth may be associated, root divergence and root resorption may be observed.^[14] In the present case, it occurred as a painless swelling in the mandibular anterior tooth region of 21-year-old-male patient in relation to 35 to 45 teeth region. Radiographically it appeared as a well demarcated unilocular radiolucency with multiple radiopaque locules within the lesion. Root resorption was noted w.r.t. 45-32 in angular pattern. According to the study by Uchiyama and al COC are unilocular with well-defined borders and margins, root resorption was encountered in seven of nine cases with divergence of teeth in eight of the nine cases, impacted teeth were reported in six of the nine cases, an odontoma was found in one case.^[5] Hirshberg et al.[21] clinically and histologically examined 52 cases of Gorlin cyst, associated with odontoma.^[13] Lida et al.[22] reported radiographic profile of 11 cases of COC and only one of them arose from edentulous mandible. Arruda et al.[23] debated that radiolucent COCs may undergo calcification and progress to a lesion of mixed radiographic appearance, thus causing swelling and cystic expansion.^[16] Microscopic features of classic calcifying odontogenic cyst is characteristic which includes a fibrous capsule with lining of odontogenic epithelium. The basal layer is made up of ameloblast-like columnar or cuboidal cells of 4-10 cells thickness overlined by loosely arranged epithelial cells similar to stellate reticulum of enamel organ. Also present are a number of epithelial cells devoid of nuclei, which are eosinophilic with their basic cell outline retained (ghost cells). Sometimes ghost cells may undergo calcification and lose their cellular outline. When this happens they form firm sheet-like area of calcified keratin.^[10] These masses of “ghost cells” may at times intrude into the fibrous capsule evoking a giant cell reaction at times seen in close proximity to or embedded within large areas of eosinophilic matrix material which many authors suggest it to be dentinoid.^[8] In our case, classic features of COC along with dentinoid adjacent to epithelial component are seen. In 1946, Thomas and Goldman introduced the term “ghost cells” which highlights the origin and nature of these lesions and describes their microscopic characteristics.^[17] Ghost cells are enlarged, ballooned, and ovoid or elongated epithelial cells with eosinophilic cytoplasm but without a nucleus and shadow appearance. Hence, these cells are also called translucent cells or shadow cells. The origin of ghost cells has been attributed to local hypoxia and degeneration, metaplastic transformation, coagulative necrosis, abortive formation of enamel matrix, abnormal terminal differentiation, or apoptosis aberrant keratinization and/or accumulation of hard keratin.^[8] Ghost cells are not unique to COC but also seen in Ameloblastoma, Odontoma, Craniopharyngioma, and other odontogenic tumors 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.^[10]

At times, COC occurs in association with other odontogenic tumors such as Odontoma/Adenomatoid Odontogenic Tumor/Ameloblastoma/Ameloblastic Fibro-Odontoma/Ameloblastic Fibroma, etc. In present case, COC is associated with compound odontoma. In the two studies by Knezevic and Buchner prevalence of Gorlin's cyst associated with odontoma was 20% and 35%, respectively.^[13] Gallana-Alverz et al.^[24] also reported a case of COC associated with odontoma in a 19-year-old boy.^[13]

The treatment of COC is that of conservative surgical enucleation of entire cyst followed by curettage. Recurrences are very uncommon as it depends on the completeness of cyst removal during surgical procedure.^[8] In our case, enucleation was done along with removal of multiple odontomas. Follow up after 6 months is done with no recurrence till date. There are reports of malignant transformation in recurrent cases of COC.^[7] However, we intend and continue to follow up the patient for further monitoring and documentation.

Conclusion

COC is a unique lesion possessing both cystic and neoplastic potential exhibiting considerable number of variants clinically, radiographically and histopathologically. COC is a rare odontogenic cyst of developmental in origin which has to be diagnosed timely with surgical intervention. Our case represents the classical features of calcifying odontogenic cyst, according to Praetorius et al. which comes under category of type 1(b) odontoma-producing type which was treated surgically by enucleation along with total removal of odontomas. The patient was on follow up for 6 months and there is no recurrence till date.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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