In 2005, calcifying odontogenic cyst was classified as a tumor and designated as a calcifying cystic odontogenic tumor (CCOT) by the World Health Organization. Calcifying odontogenic cyst develops from the reduced enamel epithelium or remnants of odontogenic epithelium. Calcifying odontogenic cysts can occur at any age starting from first decade to seventh decade of life. It occurs more commonly in the second decade of life. It occurs almost equally in both sexes with slight male predilection. The most common sites of occurrence are anterior maxilla 41.2%, posterior mandible 35.3%, anterior mandible (17.6%), and posterior maxilla (5.9%) [1] [2][3][4][5].

A 55-year-old male reported with pain in the lower right molar region since one month. Pain was insidious in onset, continuous, throbbing type and localized. Intraoral examination revealed missing 38, 48. On palpation, there was tenderness over right mandibular ramus region. Orthopantomogram revealed a well circumscribed unilocular radiolucency in the right mandibular body and angle region, extending from mesial aspect of 46 to 48 which is impacted (Figure 1). Root resorption of 46 and 47 was seen. Endodontically treated 14, 16, 17, 24, 25, 36 and impacted 48. Aspiration has shown serosanguineous fluid. Based on these clinical and radiographic findings a tentative diagnosis of unicystic ameloblastoma or Keratocystic odontogenic tumor was attained.

Surgical enucleation and curettage of the lesion was planned under general anesthesia. Crevicular incision was placed from 45 to 47 and extended onto the ascending ramus of the mandible. Full thickness mucoperiosteal flap was reflected, extraction of 46 and 47 was performed. There was thinning of buccal cortical bone. De-roofing of the cyst was done to expose the cystic cavity. Careful enucleation and curettage of the lesion was performed (Figure 2). Impacted 48 were removed and the entire bony cavity was thoroughly irrigated with hydrogen peroxide and saline. Enucleated tissue specimen was sent for histopathological examination. Postoperatively wound healing was satisfactory and orthopantomogram at sixth month follow-up visit revealed new bone formation with no recurrence (Figure 4), still the case is under follow-up.

Calcifying odontogenic cysts are usually non neoplastic with cystic features but, sometimes they appear as solid mass with neoplastic features. The solid lesions are named dentinogenic ghost cell tumor (DGCT), epithelial odontogenic ghost cell tumor (EOGCT). There has been confusion in classification and nomenclature of the lesion [6], because of its diversified histopathological features.

Praetorius in 1981 classified calcifying odontogenic cysts into a cyst entity and a neoplastic entity. The cystic entity was classified into three types [7].

Type 1: A simple monocsytic type of typical Gorlin cyst, with or without dentinoid calcified tissue

Type 2: Monocystic odontoma creative type, presence of ameloblastic fibroma tissue in the cystic wall extending into the surrounding tissue with all the characteristics of the previous type, except that the hard tissue was complex or compound odontoma

Type 3: Monocystic ameloblastomatous proliferating type with ameloblastomatous proliferation both in the walls and in the lumen, and dentinoid formation.

Calcifying odontogenic cyst presents as central lesion occurring intraosseously or as peripheral lesion occurring in the soft tissue. The more common are the central lesions [7] [8]. Clinically, Calcifying odontogenic cyst appears as a completely asymptomatic swelling with expansion of cortical plates [5]. In our case, the lesion is central with expansion of buccal cortical plate and the cyst was asymptomatic. Radiographically calcifying odontogenic cysts are seen as a unilocular or multilocular radiolucencies with well circumscribed borders. Unilocular appearance is more common than multilocular appearance. Multilocular appearance accounts for 5% to 13% of all lesions [7][8]. Calcifications may appear as small opacities giving 'salt and pepper type of pattern' or may even show large solid amorphous masses [5].

In a case series of 11 cases published by Seiji lida et al. ten cases were associated with an unerupted tooth. Adjacent tooth displacement was observed in five cases and root resorption of adjacent teeth was observed in four cases [6]. In the present case the lesion appeared unilocular with well circumscribed borders. It was associated with unerupted 48 and there was resorption of roots in relation to 46,47.

Management of calcifying odontogenic cyst is usually surgical enucleation and curettage [7] [5].

Neoplastic variants of calcifying odontogenic cyst may require an aggressive surgical approach as they have the malignant transformation potential. However, the specific diagnosis is obtained only after histopathological examination.

Recurrence rate of calcifying odontogenic cyst is very rare, only eight cases of recurrence were noted in literature [7].

Ghost cell odontogenic carcinoma is malignant counterpart of calcifying odontogenic cyst, which is rare to occur. Utaroh Motosugi et al. noted ghost cell odontogenic carcinoma arising from calcifying odontogenic cyst in three cases out of 122 cases of calcifying odontogenic cyst [9]. So far 30 cases of ghost cell odontogenic carcinoma have been reported in literature [9]. We opted for enucleation of lesion and thorough curettage of bone cavity.

Even though the recurrence rate of calcifying odontogenic cyst is very rare, there are few case reports of development of ghost cell odontogenic carcinomas from calcifying odontogenic cyst. Our follow-up radiograph did not show any signs of recurrence. However, a clinical study with larger number of cases and long-term follow-up is required.

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2. Lin CC, Chen CH, Lin LM, et al. Calcifying odontogenic cyst with ameloblastic fibroma: report of three cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004 Oct;98(4):451–60.   [CrossRef]   [Pubmed]    
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9. Motosugi U, Ogawa I, Yoda T, et al. Ghost cell odontogenic carcinoma arising in calcifying odontogenic cyst. Ann Diagn Pathol 2009 Dec;13(6):394–7.   [CrossRef]   [Pubmed]