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CASE REPORT
Year : 2019  |  Volume : 10  |  Issue : 2  |  Page : 110-115

Calcifying odontogenic cyst: Report of a case with unique features


Department of Oral Pathology, Narayana Dental College and Hospital, Nellore, Andhra Pradesh, India

Date of Web Publication9-Jul-2019

Correspondence Address:
Dr. Vandana Raghunath
Department of Oral Pathology, Narayana Dental College and Hospital, Nellore, Andhra Pradesh
India
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DOI: 10.4103/srmjrds.srmjrds_30_19

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  Abstract 

The calcifying odontogenic cyst (COC) was first categorized as a distinct entity by Gorlin et al. in 1962. It appears as a cyst lined by an ameloblastic epithelium, containing variable amounts of ghost cells and calcifications. Being a rare developmental odontogenic cyst, it accounts for about 1% of all odontogenic cysts (Shear, 1994) and represents about <6% of all odontogenic lesions. COC mimics other odontogenic cysts clinically as well as radiologically, and a definitive diagnosis can be made only by histological means. This article describes a case of COC, which presented as an anterior mandibular swelling in a 40-year-old female patient. Histologically, the presence of innumerable ghost cells with extensive areas of the partly calcifying eosinophilic matrix (suggestive of dentinoid) abutting the masses of ghost cells and the odontogenic epithelial component, set it apart from the usual histopathological findings.

Keywords: Calcifying odontogenic cyst, dentinoid, ghost cells


How to cite this article:
Kamal F, Deepthi M, Raghunath V. Calcifying odontogenic cyst: Report of a case with unique features. SRM J Res Dent Sci 2019;10:110-5

How to cite this URL:
Kamal F, Deepthi M, Raghunath V. Calcifying odontogenic cyst: Report of a case with unique features. SRM J Res Dent Sci [serial online] 2019 [cited 2019 Oct 21];10:110-5. Available from: http://www.srmjrds.in/text.asp?2019/10/2/110/262381


  Introduction Top


Calcifying odontogenic cyst (COC) also called “Gorlin cyst” is a rare developmental odontogenic lesion, introduced by Gorlin in 1962.[1] The World Health Organization (WHO) classified (2005) COC as a neoplasm and used the term calcifying cystic odontogenic tumor (CCOT) for benign cystic type, the dentinogenic ghost cell tumor (DGCT) for the benign solid type lesions which occur centrally or peripherally, and the malignant one as ghost cell odontogenic carcinoma.[2]

In 2017 classification, this lesion was reclassified as a cystic lesion again by the WHO. An international collaborative study quoted that only fewer than 90% of these lesions were either entirely cystic or associated with odontomas. For this reason, the WHO's group believed that there was no justification for classifying these lesions as neoplastic.[3]

COCs represent a heterogeneous group of odontogenic lesions that display a variety of clinic-pathological and behavioral features. COCs are grouped into cystic and solid lesions. The solid lesions represent the neoplastic type of COC. Intraosseous COCs commonly occur with similar frequency in both gnathic bones presenting as painless slow-growing well-circumscribed lesions, with the majority of them affecting the anterior (incisor/canine region).[1],[3] Radiographically, they present as unilocular, well-defined radiolucencies with or without radiopacities in the form of irregular calcifications or tooth-like densities.[3] The peripheral/extraosseous localization in the soft tissue is rare.[1] COC is known for its histologic diversity presenting as solid or cystic lesions with an ameloblastomatous component admixed with varying proportions of “ghost cells” and spherical calcifications.[4] Areas of the eosinophilic matrix material, considered to represent dentinoid, owing to the inductive effect, also may be present adjacent to the epithelial component.[3] However, these areas always remain scarce and are not seen in abundance.

We report one such case of COC that occurred in the mandible of a 40-year-old female which not only displayed abundant dentinoid but also had few more intriguing features proving the histologic ramification of COCs.


  Case Report Top


A 40-year-old female patient reported to our outpatient department with a chief complaint of a painless, slow-growing swelling of 3 months duration in the left anterior region of the lower jaw. On extra-oral examination, the swelling was diffuse and measured approximately 3 cm × 3 cm and was located over the left mandibular parasymphyseal region. There was slight facial asymmetry due to the obliteration of the left labiomental fold of the chin [Figure 1]. Added to, the patient also had angular cheilitis. It varied from soft to firm on palpation and was nontender. Intraorally, the roughly ovoid swelling extended from tooth 33 to 41 and superoinferiorly, it extended from almost the gingiva of teeth 31 and 32 to the vestibular sulcus, causing its obliteration. The covering mucosa was of normal color except for the prominent blood vessels and an area of pigmentation. It was well-circumscribed, smooth surfaced, nontender, and firm to fluctuant in areas. There was an expansion of the buccal cortex along with a possibility of perforation owing to the presence of a soft depressible spot with eggshell crackling effect. All the lower anterior teeth showed severe attrition almost to the cervical level and the left mandibular lateral incisor and right mandibular canine were grossly decayed [Figure 2]. All the other teeth too displayed generalized attrition, with moderate deposits of calculus and stain. A panoramic radiograph taken showed a well-circumscribed unilocular radiolucency with a regular thin corticated margin extending from distal aspect of the root of 41 to the distal aspect of 34 root, with resorption of 31 and 32 roots and displacement of 33 root [Figure 3]. Based on the clinical findings of grossly carious, left mandibular lateral incisor and the radiological finding of a unilocular well corticated cystic lesion a provisional diagnosis of a radicular cyst was made. Fine-needle aspiration cytology of the lesion was performed, which yielded 1.5 ml of thin straw/yellow colored, odorless, less viscous fluid. On histological examination, many chronic inflammatory cells and red blood cells in an eosinophilic, fibrinous background was noted which was suggestive of the inflammatory cystic lesion. The lesion was treated conservatively with careful enucleation and curettage along with the extraction of 31, 32, and 33 teeth under general anesthesia [Figure 4]. Gross findings were that of a ruptured cyst specimen which was brownish-black with an empty lumen [Figure 5]. It was sectioned into halves, which showed 2–2.5-mm thick folded lining with dark brown areas on the luminal surface [Figure 5]. Both the halves were processed further for histopathological examination. Microscopically, it showed an odontogenic cyst epithelial lining with occasional palisaded basal cuboidal cells and upper few layers of stellate reticulum-like cells resembling ameloblastomatous lining [Figure 6]. Few areas of the epithelial lining exhibited ghost cells replacing both the middle and superficial stellate reticulum-like cells [Figure 7]a. The underlying connective tissue capsule was fibro-cellular and -vascular with collections of ghost cells, with few undergoing dystrophic calcifications (round) and surrounded by multinucleated giant cells (MNGCs) suggestive of foreign-body response [Figure 7]a, and [Figure 7]b. Large areas of eosinophilic hyaline matrix material suggestive of dentinoid undergoing calcification in an irregular manner with embedded ghost cells and odontogenic epithelium along with MNGC bordering were also observed [Figure 8]a and [Figure 8]b. An occasional ameloblastic follicle was noted among the dentinoid material with peripheral palisaded columnar cells and central stellate reticulum-like cells [Figure 9]. The cystic lining exhibited proliferation with many tiny odontogenic epithelial islands budding or remaining adjacent to it [Figure 10]. Based on the above histopathological findings, a final diagnosis of COC was given.
Figure 1: Extra-oral view showing a diffuse swelling in the left lower para-symphyseal region with obliteration of mento-labial fold and angular chelitis of left side

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Figure 2: Intra-oral view showing an ovoid swelling involving 33–41 region with obliteration of the labial vestibule

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Figure 3: Orthopantomograph showing an unilocular radiolucency with a well-defined thin corticated border, with resorption of 31 and 32 roots and displacement of 33 root

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Figure 4: The lesion exposed surgically during enucleation

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Figure 5: Gross appearance of the ruptured dark brown cyst specimen with empty lumen. Cyst specimen sectioned into halves displaying the dark brown luminal surface and the thin folded cyst lining

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Figure 6: Odontogenic epithelial lining with occasionalpalisaded basal cuboidal cells and upper few layers of stellate reticulum like cells with undrelying vascular and fibro-cellular connective tissue (H and E, ×10)

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Figure 7: (a) Collection of ghost cells replacing the stellate reticulum layers of the cyst lining. Focal area of ghost cells with giant cell reaction and calcification in the connective tissue (H and E, ×10). (b) Collection of ghost cells with calcifications and odontogenic epithelial cells (H and E, ×20)

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Figure 8: (a) Large areas of eosinophilic matrix (dentinoid) undergoing calcification with embedded ghost cells and odontogenic cells. Few multinucleated giant cells are also seen bordering the dentinoid material (H and E, ×5). (b) Large areas of eosinophilic matrix (dentinoid) undergoing calcification with embedded ghost cells and odontogenic cells. Few multinucleated giant cells are also seen bordering the dentinoid material (H and E, ×20)

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Figure 9: An occasional ameloblastic follicle noted amidst the dentinoid material (H and E, ×5). The peripheral palisaded columnar cells and stellate reticulum cells of the ameloblastic follicle (inset [H and E, ×20])

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Figure 10: The proliferating cyst lining of calcifying odontogenic cyst along with adjacent small islands and large areas of haemorrhage (H and E, ×5)

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  Discussion Top


COC is a rare developmental odontogenic cyst, constituting about 1% of all odontogenic cysts.[5],[6] It is considered as the oral counterpart of the cutaneous calcifying epithelioma of Malherbe.[6],[7] Further COC is also referred to as Gorlin's cyst, keratinizing ameloblastoma or melanotic ameloblastic odontoma.[8]

Praetorius et al. (1981) classified COC as Type I (cystic type) and Type II (neoplastic type [DGCT]). He further sub-divided the cystic variant (Type I) into three different types as follows:

  1. Simple unicystic type
  2. Odontome-producing type
  3. Ameloblastomatous proliferating type.[9]


In 1992 WHO classification, the cystic COC represented as the nonneoplastic variant and DGCT as the solid neoplastic variant which could show an infiltrative growth pattern.[10]

Later Toida (1998) classified the cystic variant as calcifying ghost cell odontogenic cyst (CGCOC) and neoplastic variant as calcifying ghost cell odontogenic tumor (CGCOT) as mentioned below.

1. Cyst: CGCOC

2. Neoplasm:

  1. Benign – CGCOT


    • Cystic variant – Cystic CGCOT
    • Solid variant – Solid CGCOT.


  2. Malignant-Malignant CGCOT.


3. Combined lesion:

  1. Odontoma
  2. Ameloblastoma
  3. Other odontogenic lesions.[9]


In 2005, COC was reclassified by the WHO as CCOT for cystic type and DGCT for solid type based on its histological behavior.[10],[11]

In the recent classification by the WHO 2017, the cystic forms were categorized under developmental odontogenic cysts, and the solid forms were retained as mixed odontogenic neoplasms.[10]

Thus, COC is usually a well-circumscribed, cystic, or solid lesion derived from odontogenic epithelium which develops from reduced enamel epithelium or remnants of odontogenic epithelium in the follicle, gingival tissue, or bone, but contains “ghost cells” and spherical calcifications.[2],[4]

The age of occurrence of COC ranges from 1 to 82 years, with a peak incidence in the second decade. It may also show bimodal age distribution the first peak at the second decade and the second peak at the sixth to the seventh decade.[12] The cyst shows no predilection for any particular sex and affects either maxilla or the mandible. It commonly occurs anterior to the first molar region of which 75% of cases show a predilection for the incisor-canine region.[1]

The COC mainly occurs intraosseously as an asymptomatic swelling with the bony expansion of the jaw. The extraosseous variant is rare that occurs frequently on the gingiva as a nonspecific well-circumscribed sessile or pedunculated mass with a smooth surface, which may resemble gingival fibroma, gingival cyst, or peripheral giant cell granuloma.[1]

Radiographically, most of the lesions present as unilocular or multilocular radiolucencies with or without central radiopaque areas. They are either well-defined with corticated margins or have poorly defined margins.[9]

In the present case, it occurred as a cystic swelling in the left mandibular anterior region of 40-year-old female patient in relation to teeth 41, 31, 32, 33 with 32 having a deep carious lesion. Radiographically, it appeared as a unilocular radiolucency with a thin corticated margin, associated with the roots of teeth 31–34, and was also noted displacing the canine root (33).

COC often mimics other odontogenic lesions from the clinical and radiographic point of view such as calcifying epithelial odontogenic tumor, adenomatoid odontogenic tumor, ameloblastic fibro-odontoma, and dentigerous or other odontogenic cysts.[13] On similar grounds, our case too was misinterpreted to be a radicular cyst owing to the lesion being associated with a deep carious lesion of left lateral incisor tooth (32).

The distinct feature of COC is that of an odontogenic cystic lining with a well-defined basal layer of cuboidal/columnar cells with overlying stellate reticulum cells, akin to ameloblastomatous lining, demonstrating varying numbers of “ghost” epithelial cells with a propensity to calcify and a fibrous capsule.[3],[14] These masses of “ghost cells” may at times intrude into the fibrous capsule evoking a giant cell reaction.[15] These are at times seen in close proximity to or embedded within large areas of the eosinophilic matrix material, which many authors suggest it to be dentinoid. Both the ghost cells and the dentinoid material undergo calcification forming round basophilic calcified structures in the former case and irregular basophilic calcified areas in the latter terming it as dysplastic dentine.[3] Although our case showed classical features of COC, there was foreign-body reaction toward the ghost cells and also toward the dentinoid material and large areas of eosinophilic matrix with entrapped ghost cells, individual/clusters/islands of odontogenic cells, and also areas of calcified dentinoid or dysplastic dentine were noted. An occasional ameloblastic follicle was also seen. Added to it the cyst lining epithelium showed proliferations in the form of small odontogenic islands.

Our case belongs to the proliferative cyst type based on Soussan Irani, Forough Foroughi's histological classification [Table 1].[2] The dilemma is whether our case can be considered as the ameloblastomatous type, as we also noted an occasional ameloblastic follicle. Secondly though Soussan Irani and Forough Foroughi have attempted to classify the COCs based on histological appearances, some cases like ours may pose a dilemma by presenting overlapping features.[2]
Table 1: Classification of COC

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Ghost cell is an enlarged, ballooned, ovoid or elongated, elliptoid epithelial cell with eosinophilic cytoplasm but without a nucleus and shadow appearance. Hence these cells are also called shadow cells or translucent cells.[16] In routine light microscopy with H and E staining, these cells show abundant granular cytoplasm with a pale nuclear zone. Whereas electron microscopic findings show the cytoplasm to be filled with tonofilament bundles with a variety of vesicular structures scattered among these bundles, believed to be derived from mitochondria and endoplasmic reticulum.[17]

The origin of ghost cells has been traced to local hypoxia and degeneration, coagulative necrosis, metaplastic transformation, abnormal terminal differentiation or apoptosis, abortive formation of enamel matrix, aberrant keratinization and/or accumulation of hard keratin.[9],[17],[18]

COC at times occurs in association with other odontogenic tumors, such as odontoma/adenomatoid odontogenic tumor/ameloblastoma/ameloblastic fibro-odontoma/ameloblastic fibroma, etc.[4] However, our case did not exhibit features of any of these neoplasms except for the occasional ameloblastic follicle.

The treatment of COC is that of a conservative surgical enucleation of the entire cyst followed by curettage. Recurrences are very uncommon as it depends on the completeness of cyst removal achieved intra-operatively.[1],[13] The same was followed in our case and to date, there has been no recurrences.


  Conclusion Top


COC is an uncommon benign odontogenic neoplasm which may show characteristics of both a cyst and solid neoplasm. Its clinical and radiographic features may mimic other odontogenic cysts or tumors, and a definitive diagnosis can only be arrived on histological examination. Thus, the present case was diagnosed with a radicular cyst in the given spectrum of clinical and radiological findings. Only on histological examination did the features of COC come to light. Histologically, it displayed abundant areas of calcifying eosinophilic matrix suggestive of dentinoid with embedded ghost cells and odontogenic epithelium along with proliferative cyst lining and ameloblastomatous changes, signifying the histologic diversity of these neoplasms.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]
 
 
    Tables

  [Table 1]



 

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