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Year : 2014  |  Volume : 6  |  Issue : 2  |  Page : 131-136

A confocal view of the calcifying odontogenic cyst: Report of two cases

Department of Oral Pathology, Krishnadevaraya College of Dental Sciences, Bengaluru, Karnataka, India

Date of Web Publication16-Oct-2014

Correspondence Address:
Madhura Bhat
Department of Oral Pathology, Krishnadevaraya College of Dental Sciences, Via Yelahanka, Sir MVIT Campus, Bengaluru - 562 157, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0975-8844.143061

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The calcifying odontogenic cyst (COC) is a rare odontogenic lesion representing about 1% of all jaw cysts. There is a wide age range from 1 to 82 years with a first peak in the second decade and the second in the sixth/seventh decade. This lesion is characterized by the presence of "ghost" cells. The pathogenesis of the lesion is from the reduced enamel epithelium or the remnants of odontogenic epithelium. Here, we report two cases, both in 18-year-old male patients; previously diagnosed as dentigerous cyst and residual cyst respectively. But histologically, both the cases turned out to be COCs. Confocal laser scanning microscopy (CLSM) has become an invaluable tool for a wide range of investigations in the medical sciences for imaging thin optical sections of tissues. The COCs were evaluated using CLSM to analyze the properties of the cystic lining and the ghost cells.

Keywords: Calcifying odontogenic cyst, confocal laser scanning microscopy, confocal microscopy, ghost cells, keratin

How to cite this article:
Makarla S, Bhat M, Bavle RM, Kristam P. A confocal view of the calcifying odontogenic cyst: Report of two cases . J Orofac Sci 2014;6:131-6

How to cite this URL:
Makarla S, Bhat M, Bavle RM, Kristam P. A confocal view of the calcifying odontogenic cyst: Report of two cases . J Orofac Sci [serial online] 2014 [cited 2023 Feb 1];6:131-6. Available from:

  Introduction Top

Odontogenic cysts comprise of 7-13% of the lesions diagnosed in the oral cavity. [1] They are true cysts with a well delineated epithelial lining which originates from odontogenic epithelium. [2] The term calcifying odontogenic cyst (COC) was first introduced by Gorlin and his colleagues in 1962. [3] The presence of "ghost cells" in COC is its most characteristic feature. The lesion is reported and is well recognized, though rare. There has been a constant and considerable discussion on its origins, pathogenesis and histopathological variations since its first discovery. [3] Because of this diversity, it has attained various names. This includes COC, Gorlin cyst, keratinizing COC, atypical ameloblastoma, calcifying ghost cell odontogenic tumor, cystic calcifying odontogenic tumor, dentinogenic ghost cell tumor, calcifying odontogenic lesion, epithelial odontogenic ghost cell tumor, and ghost cell cyst. [4] It has recently bee renamed as 'Calcifying cystic odontogenic tumor'.

Calcifying odontogenic cyst is a rare odontogenic lesion representing about 1% of all jaw cysts. [5] There is a wide age range from 1 to 82 years with a first peak in the second decade and the second in the sixth/seventh decade. [3] There is almost an equal gender predilection, and no race predilection has been observed. [3] The lesion can occur intraosseously or extraosseously, though the intraosseous form is more frequent representing about 70-80% of the reported cases than the extraosseous form which comprises of 12-20% of the total cases. [5]

Other variants include, a pigmented variant with dendritic cells and melanin pigment in the epithelial layer along with ghost cells [6] and a clear cell variant with histomorphological similarities to calcifying epithelial odontogenic tumor. [7]

Both the intraosseous and extraosseous forms occur with about the same frequency in the maxilla and the mandible. The most common site of occurrence is the anterior part of the jaws in the canine - premolar region. Most of the peripheral lesions are located in the maxillary or mandibular gingiva or alveolar mucosa, anterior to the first molar. Clinically, most of the lesions present as asymptomatic swellings, with intraoral lesions sometimes causing bony hard expansion of the jaw. Pain is a rare feature. [3]

Confocal laser scanning microscopy (CLSM) has recently become an invaluable tool in the biological and medical sciences. This technique allows the collection of thin optical sections, without the need for physical sectioning of the tissue. Confocal microscopes can usually produce images with greater sensitivity, contrast and resolution than those produced with normal light microscopes. [8]

We report two cases of COC that occurred in young male patients along with a confocal microscopic study of the histologic sections of the cysts.

  Case reports Top

0Case 1

An 18-year-old male patient reported to the outpatient department of Krishnadevaraya College of Dental Sciences and Hospital, Bengaluru, India with a complaint of an asymptomatic swelling in the lower right jaw region present since 1½ months. The swelling had increased in size gradually over time. Extraoral examination revealed a diffuse ill defined, and nontender swelling measuring 2.5 cm × 2.0 cm in size in the right mandibular region. Intraorally, an ovoid swelling was seen in the right lower vestibule, extending from the mesial aspect of 44 to the distal aspect of 46 regions, coral pink in color with diffuse margins and stretched but intact overlying mucosa [Figure 1]. It was firm on palpation. There was a retained 85 in the region. Pulp vitality tests showed 46 was nonvital, and 44 was vital.
Figure 1: Intraoral examination reveals a firm and nontender ovoid swelling obliterating the right lower vestibule measuring about 2 × 2.5 cm in size with a stretched but intact overlying mucosa

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Intraoral periapical radiograph and orthopantomograph taken showed a well-defined unilocular radiolucency extending from the distal aspect of 44 to the mesial root of 46 involving the crown of an impacted 45. Radio-opaque flecks were visible in relation to the mesial root of 46 [Figure 2].
Figure 2: Orthopantomograph showing a well-defined radiolucency extending from mesial of 44 to distal of 46 involving impacted 45. Retained 85 present along with radio-opaque flecks in relation to mesial root of 46

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On aspiration, 2.5 ml of clear yellow fluid with tiny white colored flecks was obtained, suggesting that it was a noninfected cystic lesion, and a provisional diagnosis of dentigerous cyst was given. Following this, an incisional biopsy of the lesion was done after making a small window in the bone [Figure 3].
Figure 3: (a, b) Clear yellow fluid obtained on aspiration followed by an incisional biopsy creating a small window in the bone

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Macroscopic findings

A soft tissue specimen of 1.0 × 0.9 cm in size, roughly oval in shape, creamish brown in color, and firm in consistency was received within which creamish brown flecks were evident in some areas on grossing. The specimen was routinely processed and stained with hematoxylin and eosin.

Microscopic findings

The tissue sections showed cystic epithelium made up of prominent odontogenic epithelial cells. The basal cells were low columnar with hyperchromatic nuclei, and the overlying cells resembled stellate reticulum like cells. Numerous ghost cells could be appreciated within the epithelium. These cells had an eosinophilic cytoplasm devoid of nuclei but retained their cellular outlines. Some of them were under the process of calcification. The odontogenic epithelium was arranged in solid nests, islands, and follicles. The epithelium was proliferative and with follicles projecting into the connective tissue. The connective tissue capsule in some areas appeared immature with myxoid stroma and plump cells. The rest of the connective tissue was relatively well formed and mature [Figure 4]. Reactive bone formation was seen in the periphery of the lesion [Figure 5].
Figure 4: (a) Cystic lumen lined by prominent odontogenic epithelium with peripheral reactive bone (H and E, ×40). (b) Proliferating odontogenic epithelium forming follicles projecting into the fibrous connective tissue stroma (H and E, ×100). (c) Areas of "ghost" epithelial cells projecting into the lumen (H and E, ×200). (d) Ghost cells undergoing calcification (H and E, ×400)

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Figure 5: Photomicrograph showing reactive bone formation at the periphery of the lesion (H and E, ×40)

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Case 2

The second case is of an 18-year-old male patient who came with a chief complaint of swelling in the right upper front region of the jaw since 1 year. The swelling had gradually increased to the present size. On clinical examination, a solitary, oval shaped swelling measuring up to 5.0 × 5.0 cm was present in the anterior maxillary region extending anteroposteriorly from the zygomatic buttress to the right central incisor region, and superoinferiorly it extended from the right infraorbital margin to the upper alveolar region. On palpation, the swelling was bony hard in consistency and nontender.

A paranasal sinus view extraoral radiograph (Water's view) showed haziness and a lesion with ill-defined borders over the right maxillary antrum.

Aspiration revealed a straw colored fluid. A provisional diagnosis of a developmental odontogenic cyst was given, and the lesion was excised and sent for histopathological examination.


Macroscopic findings

A soft tissue specimen measuring 4.5 × 4.0 cm in size, creamish brown in color and irregular shape and surface and soft in consistency was obtained. The specimen was cut and routinely processed [Figure 6].
Figure 6: A 4.5 × 4.0 cm cystic lesion excised in Toto showing lumen supported by connective tissue wall

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Microscopic findings

The hematoxylin and eosin stained sections showed a cystic lumen lined by odontogenic epithelium wherein the basal cells were cuboidal to columnar in shape with nucleus polarized away from the basement membrane. Suprabasal stellate reticulum-like cells were evident. Ghost cells were present in the form of large epithelial cells with eosinophilic cytoplasm without visible nuclei. Aggregates of ghost cells were abundantly seen dispersed throughout the connective tissue capsule with few undergoing calcification. Connective tissue capsule was moderately dense with mild chronic inflammatory cell infiltrate, numerous giant cells, myxoid areas, odontogenic rests, and cholesterol clefts [Figure 7].
Figure 7: (a) Cystic lumen lined by odontogenic epithelium and stellate reticulum like cells with odontogenic rests in the connective tissue wall (H and E, ×40). (b) Presence of ghost cells adjacent to forming a cell ball in the cystic lining (H and E, ×100). (c) Ghost cell aggregates within cystic epithelium (H and E, ×100). (d) Ghost cell undergoing calcification (H and E, ×400)

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Confocal microscopic findings

Confocal microscopy

The CLSM technique consists of illuminating the sample with a bichromatic laser source. The resulting emission energy is detected by a spatially filtered optical system, the pinhole, which eliminates light signals arising from out-of-focus planes.

When analyzed by CLSM, the ghost cells in our cases appeared as brightly autofluorescent cells and this autofluorescence exhibited a characteristic pattern by forming globular spots in the cytoplasm. Higher magnification showed brightly fluorescent areas and not so bright spots in confluent masses of this kind within the ghost cells [Figure 8] and [Figure 9].
Figure 8: (a-d) Confocal laser scanning microscopy images of H and E stained sections of ghost cell aggregates. Ghost cells autofluorescence. Brighter fluorescence indicates higher amounts of keratin like material (×100)

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Figure 9: Confocal image of confluent masses of ghost cells (CLSM, ×400)

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  Discussion Top

Calcifying odontogenic cyst is a rare odontogenic cyst with both central and peripheral variants occurring in the jaw region. All centrally located COCs are said to arise from the reduced enamel epithelium or from the remnants of odontogenic epithelium. Two major sources of pathology are considered for the histogenesis of the peripheral neoplastic variant. Those lesions located entirely within the connective tissue of the gingiva and were separated from the surface epithelium by a band of connective tissue; very likely arise from the remnants of the dental lamina whereas other lesions appear to arise from the oral surface epithelium. [4]

The central COC presents as an asymptomatic swelling of the jaws, with pain being a rare feature and mostly associated with secondary infection. These lesions may produce a hard buccal bony expansion. Lingual cortical plate expansion may sometimes be observed. Occasionally this lesion can perforate the cortical plate and extend in to the soft tissues. [3] Both the cases which reported to our hospital were asymptomatic swellings of the jaws, the mandible in the first-case and the maxilla in the second case, presenting as hard bony swellings with buccal cortical plate expansion. These features are in accordance with the classical clinical findings of COC seen in our cases.

Radiographically, COCs appear as unilocular or as multilocular radiolucencies. It commences with a radiolucency and matures into the mixed radiolucent - radio-opaque stage as seen in our first case. Three general patterns of radio opacity are seen. A salt and pepper pattern of flecks, a fluffy cloudlike pattern throughout, and a crescent-shaped pattern on one side of the radiolucency in a "new moon" like configuration. [9] Resorption of the adjacent tooth roots and root divergence has been reported. One-third of the cases are associated with one or more unerupted teeth as in our first case. [3]

Extraosseous lesions show localized superficial bone resorption, or saucer shaped radiolucencies and sometimes displacement of the adjacent teeth [3] as was observed in our second case.

Histopathologically, a classic COC presents as a cystic lesion with the lining epithelium showing a well-defined basal layer of palisaded columnar or cuboidal cells with hyperchromatic nuclei with reverse polarity and an overlying epithelial cell layer of varying thickness resembling stellate reticulum. Epithelial budding into the adjacent connective tissue and epithelial proliferations projecting into the lumen are also frequent findings. Apart from these, sometimes melanin deposits are also found in the epithelial linings. Masses of ghost cells that may be confined to the epithelial lining or may be extending in to the connective tissue are characteristic features of COC. These ghost cells may sometimes be calcified. The cyst is occasionally associated with dysplastic dentin deposition or an area of hard tissue deposition resembling an odontoma. [3]

Ghost cells in COCs have been compared to those found in the calcifying epithelioma of Malherbe in the skin. Under the light microscopex, ghost cells appear as swollen, pale, eosinophilic cells. They are seen either singly or in sheets with clear conservation of basic cellular outline (if not fully coalesced), generally with apparent clear areas or with some remnants indicative of the site previously occupied by the nucleus. [10]

The ghost cells represent an abnormal type of keratinization and have an affinity for calcification. These ghost cells may undergo calcification and lose their cellular outline to form a sheet like-area. Many hypotheses have been advanced for the nature of ghost cells; few include:

  1. They are considered as abnormal keratinized bodies.
  2. They might represent simple cell degeneration or a form of enamel matrix.
  3. They might arise from the process of apoptosis of the poorly differentiated odontogenic cells, [11],[12] and
  4. They may represent the product of coagulative necrosis of the odontogenic epithelium. [3]

Ghost cells may be in contact with the connective tissue wall of the cyst where they may evoke a foreign body reaction with the formation of multinucleated giant cells. [3]

They have the same histological reactions as keratin, giving a yellow fluorescence with rhodamine B. They also give a yellow stain with Van Gieson. Immunohistochemically, ghost cells do not give a positive response for cytokeratin, involucrin and filaggrin suggesting that the ghost cells might be undergoing keratinization. Bax, an apoptotic protein, is expressed in ghost cells whereas Bcl-X an anti-apoptotic protein is not expressed. In contrast, the nucleated cells adjacent to ghost cells exhibited both Bax and Bax L. This suggests that ghost cells are formed during terminal differentiation as an apoptotic process. [12]

Confocal laser scanning microscopy has established itself as a major advance in biological imaging and now is a well-recognized technique in many fields of medicine. [8] This type of microscopy can be considered midway between optical and electronic microscopy. Not only does it allow high-resolution, thin, optical sections of biological tissues, but also three-dimensional configurations of the cellular components along with slice options. The samples of interest do not require any particular dye like rhodamine or any other fluorescent stains. Simple hematoxylin and eosin-stained sections give excellent results.

The CLSM analysis shows different fluorescence of different tissues. [11] Here, we used CLSM as an adjuvant to already available techniques for analyzing ghost cells in COCs wherein we were able to find areas showing greater keratinization by the degree of their autofluorescence. Thus, CLSM may add further value in analyzing and defining the nature and extent of keratinization processes in calcifying cystic odontogenic tumor ghost cells.

We were able to observe clear autofluorescence of ghost cells. This autofluorescence could be attributed to the presence of hard keratins in the ghost cells. [11] Although their nature is still unclear, the majority of authors consider these cells a form of true or aberrant keratinization. The fluorescence may be ascribed to keratin presence, in agreement with a number of studies reporting high autofluorescence intensity of keratin. [13]

Ultrastructure of ghost cells has suggested that these cells contained many haphazardly arranged bundles of tonofilaments of 60-240 nm in diameter. No intact intracellular organelles were observed in their cytoplasm. They were attached to neighboring ghost cells with scanty desmosomes, and their cell membranes were discontinuous in parts. Vesicles resembling matrix vesicles, 90-450 nm in diameter, were scattered among the tonofilaments, and some contained needle-like crystals that were thought to be the initial calcification sites in ghost cells. Thickening of the cell membrane in keratinized cells results from the accumulation of involucrin proteins on the inner aspect of the cell membrane. This thickened cell membrane acts as a permeability barrier. The aberrant calcification of the ghost cells occurs in the absence of thickened cell membrane produced by involucrin. Lack of such a barrier in degenerating keratinized cells would allow influx of calcium ions and water to cause cellular swelling. [14]

Ultrastructural studies have also shown mitochondrial and endoplasmic reticulum residues scattered among keratin filaments in ghost cells. Degeneration of these membranous structures liberates free fatty acids that attract calcium ions. It seems likely that ghost cells become calcified by this process, truly a dystrophic calcification. [14]

The COC can be treated by conservative surgical enucleation with a good follow up unless it is associated with another odontogenic tumor, in which case wider excision may be required. In the presence of a complex odontome, conservative treatment has been found to be adequate. An ameloblastoma or one of its variants with foci of ghost cells must be treated as would be an ameloblastoma without ghost cells. Reported recurrences of COCs are rare. The cases discussed here were treated by conservative surgery and follow-up revealed no evidence of any recurrence or complications.

  Conclusion Top

Calcifying odontogenic cyst may mimic numerous odontogenic and nonodontogenic lesions, making diagnosis difficult. Therefore, careful understanding of specific clinical and histological features is crucial. Our cases represent classical findings of COC and the use of CLSM has enhanced our understanding of ghost cells.

  References Top

Prockt AP, Schebela CR, Maito FD, Sant'Ana-Filho M, Rados PV. Odontogenic cysts: Analysis of 680 cases in Brazil. Head Neck Pathol 2008;2:150-6.  Back to cited text no. 1
Eshghyar N, Jalayer-Nadery N, Ashery R. Calcifying odontogenic cyst: An analysis of thirty six cases: Acta Med Iran 2006;44:59-62.  Back to cited text no. 2
Shear M, Spheight P. Cysts of the Oral and Maxillofacial Regions. 4 th ed. Singapore: Blackwell Munksgaard Publication; 2007. p. 100-7.  Back to cited text no. 3
Riechart PA, Phillipsen HP. Odontogenic Tumors and Allied Lesions. 9 th ed. London: Quintessence Publishing Co. Ltd.; 2004. p. 155-70.  Back to cited text no. 4
Seyedmajidi M, Feizabadi M. Peripheral calcifying odontogenic cyst. Arch Iran Med 2009;12:309-12.  Back to cited text no. 5
Takeda Y, Kuroda M, Suzuki A, Fujioka Y. Pigmented variant of calcifying odontogenic cyst. Report of an additional case and review of the literature. Acta Pathol Jpn 1985;35:1023-7.  Back to cited text no. 6
Ng KH, Siar CH. Clear cell change in a calcifying odontogenic cyst. Oral Surg Oral Med Oral Pathol 1985;60:417-9.  Back to cited text no. 7
Claxton NS, Fellers JT, Davidson MW. Laser scanning confocal microscopy. Available from: [Last accessed on 2012 Oct 11].  Back to cited text no. 8
Marx RE, Stern D. Oral and Maxillofacial Pathology - A Rationale for Diagnosis and Treatment. India: Quintessence Books; 2003. p. 607.  Back to cited text no. 9
Mehendiratta M, Bishen KA, Boaz K, Mathias Y. Ghost cells: A journey in the dark. Dent Res J (Isfahan) 2012;9:S1-8.  Back to cited text no. 10
Lucchese A, Scivetti M, Pilolli GP, Favia G. Analysis of ghost cells in calcifying cystic odontogenic tumors by confocal laser scanning microscopy. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;104:391-4.  Back to cited text no. 11
Kim J, Lee EH, Yook JI, Han JY, Yoon JH, Ellis GL. Odontogenic ghost cell carcinoma: A case report with reference to the relation between apoptosis and ghost cells. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;90:630-5.  Back to cited text no. 12
Lucchese A, Petruzzi M, Scivetti M, Pilolli GP, Di Bisceglie MB, Crincoli V, et al. Calcifying odontogenic cysts associated with odontomas: Confocal laser scanning microscopy analysis of 13 cases. Ultrastruct Pathol 2011;35:146-50.  Back to cited text no. 13
Johnson A 3 rd , Fletcher M, Gold L, Chen SY. Calcifying odontogenic cyst: A clinicopathologic study of 57 cases with immunohistochemical evaluation for cytokeratin. J Oral Maxillofac Surg 1997;55:679-83.  Back to cited text no. 14


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


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