Different manifestations of calcifying cystic odontogenic tumor

Received on: Feb 3, 2012 – Accepted on: Aug 3, 2012 ABSTRACT The calcifying cystic odontogenic tumor normally presents as a painless, slow-growing mass, involving both maxilla and mandible, primarily the anterior segment (incisor/canine area). It generally affects young adults in the third to fourth decades, with no gender predilection. Computerized tomography images revealed important characteristics that were not detected by panoramic radiography, such as fenestration, calcification and tooth-like structures. The typical microscopic feature of this lesion is the presence of variable amounts of aberrant epithelial cells, without nuclei, which are named “ghost cells”. In addition, dysplastic dentine can be found and occasionally the cyst can be associated with an area of dental hard tissue formation resembling an odontoma. The treatment for calcifying cystic odontogenic tumor involves simple enucleation and curettage. The purpose of this article is to present two different manifestation of calcifying cystic odontogenic tumor in which computerized tomography, associated to clinical features, served as an important tool for diagnosis, adequate surgical planning and follow-up of patients.


INTRODUCTION
The calcifying cystic odontogenic tumor (CCOT) is a new designation of calcifying odontogenic cyst (COC) recommended by the 2005 classification of the World Health Organization (WHO).A variety of clinical and histopathologic features was previously described, and several classifications have been proposed (1)(2)(3)(4) .
Histologically, CCOT is usually composed of a cystic cavity with fibrotic capsule lined by an odontogenic epithelium.The typical microscopic feature of this lesion is the presence of variable amount of aberrant epithelial cells, without nuclei, which are named "ghost cells".In addition, dysplastic dentine can be found and occasionally the cyst is associated with an area of dental hard tissue formation resembling an odontoma (4,7,10) .
The treatment of CCOT involves simple enucleation with vigorous curettage of the lesion and long term follow-up (6,11) .
The purpose of this article is to report two different manifestations of CCOT, in which computerized tomography (CT) served as an important tool for an adequate planning of surgical removal of the lesion.

CASE 1
A 36 year-old white female was referred to the Oral and Maxillofacial Surgery Department of Hospital das Clínicas, São Paulo, Brazil, by her dentist, due to a swollen area in the upper left canine area for 8 months.The patient was asymptomatic, and her medical history was uneventful.The intraoral inspection showed a small vestibular tumefaction at the caninae fossae, as well as the absence of the permanent canine and the first biscupid teeth.The mucosa aspect was normal (Figure 1).
Periapical radiography showed impacted canine in apparent association with a radiopaque mass and an osteolytic lesion (Figure 2).Panoramic radiography showed displacement of two teeth (canine and first bicuspid) and a radiolucent unilocular lesion partially occupied by a radiopaque mass, resembling an odontoma and involving the left first bicuspid and the canine (Figure 3).
CT was performed for a more complete evaluation.CT images revealed a well-defined circumscribed isodense expanding lesion with thin cortical plate in the left posterior area.Complete opacification of the left sinus was also observed (Figure 4A).Two fragments of radiopaque masses at the distal margin were detected (Figure 4B).The clinical and radiological diagnoses included calcifying odontogenic tumor and odontoma.Aspiration of the lesion presented a brown serous liquid.Surgical enucleation was performed under general anesthesia.An intraoral approach was performed and the lesion was exposed.A thick wall cyst was completely removed, with a dentin-like material and enamel compatible with a compound odontoma inside the cyst.The impacted canine and bicuspid teeth were extracted (Figures 5A  and 5B).
Microscopical examination showed a cystic cavity lined by a prominent and well-defined basal layer of cuboidal and luminar cells that focally resembled ameloblastic epithelium with numerous ghost cells and calcified particles.Multiple tooth-like structures were found in the cystic lumen (Figures 6A to 6C).The histopathologic diagnosis was calcifying odontogenic cyst associated with odontoma.
right facial swelling and the facial skin was not affected.The intraoral examination showed an expansion in the lower gingivolabial sulcus of right incisors, canine and molars extending to posterior area.The patient was asymptomatic and a normal mucosa was observed in the examination (Figure 7).
Radiographic exams showed a radiolucent, unilocular lesion with well-defined margins and diffuse radiopaque calcifications.No relation with uneruputed tooth could be seen (Figure 8).CT images showed a wellcircumscribed isodense mass with anteroposterior and lateromedial expansion of the cortices, containing irregular star-shaped opacities in the anterior portion of the mandible (Figure 9).We reported a normal clinical recovery of the patient after surgery and, after 2 years of follow-up, no recurrence of the lesion was observed.

CASE 2
A 17 year-old male with no relevant medical history was referred to Oral and Maxillofacial Surgery Department of Hospital das Clínicas, for an asymptomatic swelling in the mandible.The extraoral examination showed a All teeth associated with the lesion showed positive response to vitality tests.
Aspiration of the lesion showed a brown serous liquid content.Incisional biopsy was made under local anesthesia.The histopathologic findings showed a CCOT.Similar findings were seen as in case 1, but no tooth-like components were found.
Total enucleation of the lesion was performed under general anesthesia.Postoperative evolution was satisfactory without complications after 18 months of follow-up.No signs of recurrence were seen.

DISCUSSION
Some authors classified CCOT within the groups of neoplasms and tumors that originate form odontogenic tissues but confirmed that most of the cases were nonneoplastic (4,12) .
CCOTs are usually painless and slow growing tumors (13,14) .When located in the maxilla, patients may sometimes complain of nasal stiffness, epistaxis and headache.Despite of paranasal sinus involvement, the patient described in case 1 did not present any of these symptoms.In case 2, despite the involvement of anterior mandible, the patient was asymptomatic.
The CCOT is rarely associated with other odontogenic tumors, such as ameloblastic fibroma, ameloblastic fibro-odontoma, odontoameloblastoma, or odontogenic myxofibroma (4,7,15) .In the case 1, a rare situation of calcifying odontogenic cyst associated with odontoma was demonstrated.No associated tumors were found in the case 2.
Most cases are intraosseous and radiographically appears as well-defined, unilocular or multilocular radiolucencies with occasional radiopaque deposits of varying sizes and opacities (8,13,16) .In case 2, an unilocular intraosseus lesion with well-defined margins and diffuse radiopaque calcifications was seen.
When calcified material is detected, the possibility of adematoid tumor, ossifying fibroma, calcifying epithelial odontogenic tumor, and odontoma should be considered (11,17) .In case 1 the lesion revealed an unilocular well-demarcated radiolucency with radiopaque calcified mass involving the left first bicuspid and the canine teeth.The clinical, histological and radiological diagnosis was CCOT with odontoma.
CT is an important tool for visualization of the internal structure of the lesion and the involvement of neighboring structures, with high reproducibility of measurements for all dimensions.It has been considered very helpful for clinical diagnosis and treatment planning (18) .CCOT generally appear as an unilocular lesion with well-defined margin.Tooth divergence and root resorption were common (19) .In both cases reported, CT images revealed important characteristics that were not detected by panoramic radiography, such as fenestration, calcification, and tooth-like structures.Both cases showed a well-defined margin.
We considered CT indispensable for surgical planning.In our cases, CT examination was used to confirm the presence of calcifications along the cyst wall and of tiny flecks that could not be detected by simple radiographic images.
As to histology, both cases were characterized by a well-defined basal layer of cuboidal and luminar cells that focally resembled ameloblastic epithelium with numerous ghost cells and calcified particles.Case 1 was also associated with tooth-like materials (odontoma).Case 2 presented numerous ghost cells and calcified elements but no tooth-like components were found.
CCOT treatment depends on the lesion site and histological pattern (22) , and includes simple enucleation and curettage, which means enucleation followed by removal of a 1-to 2-mm layer of bone around the periphery of the cystic cavity with a sharp curette or a bone bur.The objective of this procedure is to remove epithelial debris that could originate a recurrent lesion (11,17) .Souza et al. (11) reported that marsupialization could be indicated as preliminary treatment to CCOT to minimizing damages in anatomical structures.
Buchner (6) highlighted the importance of the long term of follow-up.Recurrence is infrequent and malignant behavior is rare (4) .
We emphasize that the choice of treatment should be individualized for each lesion since radiological and histological features may differ from one lesion to another.It could be possible to correlate some characteristics of the macroscopic examination of the surgical specimen and the CT images.
CCOT is a benign odontogenic neoplasm that may manifest occasionally as an aggressive and recurrent tumor (11,17) .In both cases, a conservative treatment was chosen with complete enucleation of the tumor.No recurrence and complications were observed during the follow-up period.
In conclusion, CT scan served an important tool in making an appropriate surgical planning of the lesions in both cases.Definitive diagnosis required pathological examination.Long-term follow-up visits are recommended especially if adjacent structures are also affected.

Figure 1 .
Figure 1.Preoperative intraoral condition showing a vestibular tumefaction at the canine fossae and absence of the permanent canine and first bicuspid

Figure 2 .Figure 3 .Figure 4 .
Figure 2. Panoramic radiograph showing displacement of two teeth and a radiopaque mass related to the cystic lesion

Figure 5 .Figure 6 .
Figure 5. (A) Intraoral surgical aspect showing a calcified lesion as hard as the maxillary bone.(B) Macroscopic view of the surgical resection and extracted impacted canine and first bicuspid teeth

Figure 7 .Figure 8 .Figure 9 .
Figure 7. Preoperative intraoral condition showing expansive tumefaction in the anterior region of the mandible causing deviation of the midline