|Year : 2015 | Volume
| Issue : 1 | Page : 123-126
Ameloblastomatous calcifying odontogenic cyst: A rare histologic variant
Basavaraj N Kallalli, Kamala Rawson, Vikalp Patel, Shruthi Patil
Department of Oral Medicine and Radiology, Narsinhbhai Patel Dental College and Hospital, Visnagar, Gujarat, India
|Date of Submission||02-Dec-2014|
|Date of Acceptance||13-Sep-2015|
|Date of Web Publication||12-Oct-2015|
Basavaraj N Kallalli
Department of Oral Medicine and Radiology, Narsinhbhai Patel Dental College and Hospital, Visnagar, Gujarat
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Ameloblastoma is a well-known odontogenic tumor that can be associated with calcifying odontogenic cysts (COCs), but only a few reports give its clinical and radiographic features. Calcifying odontogenic cyst was first categorized as a distinct entity by Gorlin et al., and has been named after him since then. Calcifying odontogenic cyst is an uncommon developmental odontogenic lesion that demonstrates histopathologic diversity. It is well known that this lesion can occur in association with odontogenic tumors such as complex odontoma and ameloblastoma. The term COC was not included by the World Health Organization (WHO) in its report of 2005 and is called calcifying cystic odontogenic tumor (CCOT). Histopathologic examination of ameloblastomatous CCOT reveals ameloblastic islands containing ghost cells. Although association of ameloblastoma with this lesion is important, only a few cases have been reported in literature. The present case report is of ameloblastomatous calcifying cystic odontogenic tumor, a rare histologic variant, in a 20-year-old male patient in the left mandibular posterior region.
Keywords: Ameloblastomatous COC, calcifying cystic odontogenic tumor, calcifying epithelial odontogenic cyst, ghost cells
|How to cite this article:|
Kallalli BN, Rawson K, Patel V, Patil S. Ameloblastomatous calcifying odontogenic cyst: A rare histologic variant. J Indian Acad Oral Med Radiol 2015;27:123-6
|How to cite this URL:|
Kallalli BN, Rawson K, Patel V, Patil S. Ameloblastomatous calcifying odontogenic cyst: A rare histologic variant. J Indian Acad Oral Med Radiol [serial online] 2015 [cited 2020 Mar 29];27:123-6. Available from: http://www.jiaomr.in/text.asp?2015/27/1/123/167131
| Introduction|| |
Calcifying odontogenic cyst (COC) is an uncommon developmental odontogenic cyst, first described by Gorlin in 1962.  Calcifying odontogenic cyst is a well-circumscribed, solid, or cystic 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. It has no sex predilection and shows equal distribution in the maxilla and mandible.  About 65% of cases are found in the incisor and canine areas. 
Radiographically, COC may appear as unilocular or multilocular radiolucencies with discrete, well-demarcated margin. The most characteristic histologic features are the presence of variable number of ghost cells within the epithelial components. Prognosis of patient with COC is good and only a few recurrences have been reported.  They may also show ameloblastomatous proliferative activity intraluminally or intramurally. The neoplastic variant of COC shows a solid growth pattern consisting of ameloblastoma-like strands and islands of odontogenic epithelium infiltrating into mature fibrous connective tissue. Herein, we report a case of ameloblastomatous COC. 
| Case Report|| |
A 20-year-old male patient presented to the Department of Oral Medicine and Radiology with the chief complaint of swelling in the lower left back tooth region of jaw since 2 years. The swelling started gradually and increased to attain the present size. No history of pain and other associated signs and symptoms were present. His past medical history and dental history were non-contributory. Extraoral examination revealed a solitary swelling present on the lower left angle of mandible, measuring 3 × 2 cm in diameter, which was non-tender and bony hard in consistency [Figure 1]. Intraorally, swelling was present in the left buccal sulcus with obliteration, extending from mesial aspect of 35 to distal aspect of 37, with grade one mobility of 36 and 37. Mucosa over the swelling was normal. Vitality test revealed 36 and 37 were non-vital. Aspiration was performed which was negative. On the basis of history and clinical examination, provisional diagnosis was given as benign odontogenic tumor of the jaw [Figure 2].
|Figure 1: Extraoral photograph showing swelling of the lower left angle and body region|
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|Figure 2: Intraoral photograph reveals obliteration of left buccal vestibule|
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Panoramic radiography revealed a well-defined radiolucency involving the left body and ramus of the mandible from tooth 36 to the coronoid process. The lesion measured about 3 cm × 6 cm in size and was oval in shape. The lesion was surrounded by a corticated margin, which was showing scalloping. The lesion had enclosed tooth 38 from its root and showed multiple thin septae. The lesion had caused expansion of bone in the region of inferior border of the mandible and anterior border of the ramus, displaced tooth 38 inferiorly, and caused resorption of the roots of teeth 36 and 37 [Figure 3]. Axial section in computed tomography (CT) revealed presence of a large unilocular radiolucency with the expansion of well-corticated buccal and lingual cortical plates [Figure 4]a and b. Differential diagnosis included ameloblastoma, calcifying epithelial odontogenic tumor, odontogenic myxoma, and central giant cell granuloma.
|Figure 3: Panoramic radiograph reveals a multilocular radiolucent lesion extending from the mesial aspect of 36 to ramus, coronoid process, and neck of condyle|
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|Figure 4: (a) Axial CT showing expansion of buccal and lingual cortical plate. (b) 3-Dimensional CT showing bony expansion at the left mandibular body and angle region|
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Patient was treated surgically. Under general anesthesia, left hemimandibulectomy with reconstruction was done [Figure 5]. Photomicrograph revealed a cystic lesion lined by odontogenic epithelium. The lesion showed cystic lining containing basal tall columnar cells with reverse polarity of the nucleus. Few areas showed ghost cell on the luminal side and juxtaepithelial hyalinization. Connective tissue stroma was hyalinized in most of the areas. Stroma showed ameloblastic islands and few areas showed loosely arranged collagenous stroma with intense infiltration of inflammatory cells comprising lymphocytes and plasma cell. On the basis of the histopathological report, the final diagnosis was given as ameloblastomatous COC [Figure 6]a and b.
|Figure 5: Postoperative panoramic radiograph showing hemimandibulectomy on the left side with reconstruction|
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|Figure 6: (a and b) Photomicrographs showing odontogenic epithelium with presence of ghost cells and ameloblastic islands|
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| Discussion|| |
The COC is an uncommon lesion that demonstrates considerable histologic diversity and presents variable clinical behavior. Although it is widely considered to represent a cyst, some investigators prefer to classify it as a neoplasm.  Since the first description by Gorlin et al., many cases of COCs have been reported in the literature; but, in general, only a few cases have been reported at a time.  Calcifying odontogenic cyst represents about 1% of all cysts of the jaws. The majority of the COCs arise centrally in bone, but several peripheral (extraosseous) examples have been reported.  The age of occurrence of the cyst has been reported to vary from 3 to 80 years, with a definite peaking found in the second decade. The cyst is usually asymptomatic unless secondarily infected. Some cases have been reported where the cyst concomitantly occurred with other odontogenic lesions.  Radiographically, the lesion appears as a well-defined, unilocular or multilocular, often quite large radiolucency that may or may not contain varying amounts of radiopaque material with unerupted tooth. Root resorption or root divergence may also be observed. The present case showed multilocular radiolucency extending in the left body and ramus, and extending up to the neck region with impacted 38. 
Ameloblastomatous COC microscopically resembles unicystic ameloblastoma, except for the ghost cells and calcification within the proliferative epithelium. Ameloblastoma ex COC designates an ameloblastoma arising from the cyst lining epithelium of COC.  The present case had similar microscopic findings. It is well known that the epithelial lining of the COC has the ability to induce the formation of dental tissue in the adjacent connective tissue wall. Some reports showed that COC often coexists with other odontogenic tumors such as ameloblastoma, ameloblastic fibroma, ameloblastic fibro-odontoma, etc. 
Praetous et al., Hong et al., and Buchner ,, have attempted to classify the COC based on the dualistic concept in contrast to the earlier monistic concept. However, it seems the question concerning the nature of COC has been solved more recently by Toida who classified COC into a cyst and a neoplasm.  The classification advocated by Hong et al.  has two categories for COC associated with ameloblastoma: The ameloblatomatous cystic variant and the neoplastic variant associated with ameloblastoma. The former is characterized by a unicystic structure in which the lining epithelium shows unifocal or multifocal intraluminal proliferative activity that resembles ameloblastoma, although it also contains isolated or clustered ghost cells and calcifications. The latter is called ameloblastoma arising from COC (ameloblastoma ex COC). It is characterized histopathologically by few or no ghost cells with calcification observed in the transformed ameloblastomatous epithelial portion, while the cyst lining of the epithelium contains considerable number of ghost cells and calcifications.
| Conclusion|| |
Ameloblastomatous COC is a rare histologic variant. There are very few cases reported with this variety of COC in the literature. Several authors have suggested that if COC is associated with an ameloblastoma, its behavior and prognosis will be that of an ameloblastoma, not of COC. Careful postoperative observations are necessary for COCs which are associated with ameloblastoma. COC has been found to be of extensive diversity in its clinical and histological features as well as in its biologic behavior.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]