Introduction
Gorlin in 1962 first introduced the clinic pathological entity calcifying odontogenic cyst.1 It accounts for 0.3-0.8% of all odontogenic cysts.2 Extreme diversity is shown in its clinical, histopathological as well as in its biological characteristics. This cystic lesion arises from odontogenic epithelial remnants confined within maxilla and mandible or gingival tissues. It mostly arises intraosseously, but it may also occur extraosseously. Both jaws are affected with equal frequency, no gender predilection with peak incidence in the second and sixth decade of life.3 Roentographically cysts commonly occur in the mandible and appear as unilocular or multilocular radiolucencies. Cystic lining demonstrating characteristic "Ghost" epithelial cells with a disposition to calcifation is a noteworthy histopathological feature of these entity.4 On the contrary dentigerous cysts arises as a result of cystic change in the remains of the enamel organ after the process of enamel formation is complete.5 They entrench an unerupted tooth crown as fluid collects between layers of epithelium or between the epithelium and enamel and are attached to the cemento enamel junction. Dentigerous cysts are mostly considered developmental cysts. Their size varies and cysts have ample potential to grow large enough to cause consequential expansion of the jaw, displacement of adjacent teeth and anatomical structures, pathological fractures; however resorption of the root apex is rare.6
Case Report
A 36 year old male reported to department of Oral Medicine, Diagnosis and Radiology, Institute of Dental Education and Advance Studies, Gwalior, Madhya Pradesh with a chief complaint of pus discharge in lower left back jaw region for the past 2.5-months duration. The patient did not have any symptoms such as pain or paresthesia. Medical and family histories were noncontributory. This was patient first dental visit. On extra oral examination, no facial asymmetry was evident. On intraoral examination hard tissue findings revealed.
Teeth present 18 17 16 15 14 13 11 21 22 23 24 25 26 27
48 47 46 45 44 43 42 41 51 52 53 54 55 56 57
Figure 1
Panoramic radiograph depicting well defined homogenous unilocular radiolucency present in 37 38 region. It also reveals inverted impacted 38.
Generalized extrinsic stains were present. Soft tissue findings revealed no intra swelling or sinus evident and no tenderness was present in left molar region. The mucosa around the lesion area had normal color. Radiographic investigations were evident. A panoramic radiograph revealed a unilocular radiolucent lesion with well-defined sclerotic margins involving apices of 37 and extending posteriorly till inverted impacted 38. The third molar was dislocated distally. Other findings were congenitally missing 12 and 28. Radiographic investigations also revealed generalized interdental bone loss (Figure 1). Provisional diagnosis of dentigerous cyst was given. Ameloblastoma was considered as differential diagnosis. Patient was sent to department of Oral and Maxillofacial Surgery for surgical intervention. Prior to surgical intervention cone beam computed radiography was advised for a more complete evaluation. It revealed a well-defined circumscribed hypodense expanding lesion involving 37 38 region with thin underlying inferior border of mandible. (Figure 2). Surgical enucleation of lesion, bone curettage along with extraction of 37 38 is carried out under local anesthesia (Figure 3, Figure 4, Figure 5). The surgical specimen was fixed in formalin and was sent to department of Oral Pathology. Tissue sections were routinely processed and were embedded in paraffin. Haematoxylin and eosin staining was carried out. Histological findings revealed 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 (Figure 6). Final diagnosis was given as calcifying odontogenic cyst.
Discussion
Calcifying odontogenic cyst is an uncommon odontogenic lesion. It is arduous to diagnose this entity as it exhibits various clinical and roentographic presentations.7 It emerges within the follicle of impacted teeth and this stresses the importance of histopathological examination of all dental follicles.8 Both calcifying and dentigerous cysts can arise at any site in the oral cavity with former cases occurring mostly prevalent in anterior maxilla, followed by the posterior mandible whereas later mainly prevalent in posterior mandible.9 Our case report illustrates calcifying odontogenic cyst in posterior mandible. Cystic lesions that arise within the mandible can cause bony remodelling that can enfeeble the bone, leading to altered functional characteristics and making patient susceptible to superimposed infection and pathologic fracture.10 This applies to both calcifying and dentigerous cysts making them as strong differential diagnosis. One of common presentation of both calcifying odontogenic cysts and dentigerous cysts is asymptomatic swelling. This clinical feature is associated with lesions occurring in both extra osseous and intra osseous sites with an expansion of buccal and/or lingual cortical plates frequently appearing with the latter.11 Most of calcifying odontogenic cysts and dentigerous cysts are asymptomatic, often an incidental finding revealed on radiographic examination. Roentographic features of calcifying odontogenic cysts includes well circumscribed unilocular radiolucency with calcifications of varying density and in some cases it may present as multilocular lesion. 12 The present case exhibits unilocular variant without opacification. Dentigerous cyst mainly exhibits unilocular pattern but multilocular variant is also found in few cases. Multiplanar imaging is an essential tool for precise visualization of the internal structure of the lesion and the involvement of contiguous structures, with high reproducibility of measurements for all dimensions. It has been considered very helpful for clinical diagnosis and treatment planning.13 Incidence of root divergence and root resorption are high in calcifying odontogenic cysts as they are frequently situated in the periapical or lateral periodontal area of the dentition whereas in dentigerous cysts root resorption is rare. But in present case root resorption is not evident.14 Microscopic features of calcifying odontogenic cyst includes amorphous structures with well-defined borders without nucleus known as ghost cells, and the eosinophilic dentinoid like material and basophilic round to irregular calcified masses where about histopathological findings of dentigerous cyst includes fibrous connective tissue, hyperplastic non-keratinized epithelium, elongated interconnecting rete ridges, chronic inflammatory cells, cholesterol clefts, possibly formation of cholesterol granuloma, Rushton bodies, scattered mucous, or ciliated or sebaceous cells, small, inactive appearing odontogenic epithelial rests and dystrophic calcifications occasionally.14 In our case report ghost cells were main histopathological finding.
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