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Dentinogenic ghost cell tumor (DGCT) is an uncommon odontogenic tumor considered to be the solid, tumorous variant of calcifying odontogenic cyst. DGCT is characterized by islands of ameloblastoma-like epithelial cells that resemble the enamel organ, the presence of ghost cells, and dentinoid material. This article reports a rare case of dentinogenic ghost cell tumor associated with an odontoma in an adult patient, with a review of the literature. To the best of the authors' knowledge, there have only been four case reports of DGCT associated with odontoma, all of which occurred in children and adults younger than 30 years old.

The purpose of this report is to highlight the presentation and review the clinical and histopathological features of DGCT. There have been 130 DCGT diagnoses reported in the literature. DGCT is part of the odontogenic ghost cell tumor family which also includes the calcifying odontogenic cyst (COC) and the ghost cell odontogenic carcinoma (GCOC). In June of 2018, a 48-year-old female presented with a painless, soft tissue growth overlying the right mandibular alveolar ridge. Further workup of the lesion included a panoramic radiograph and maxillofacial computed tomography (CT) which revealed a well-defined, multilocular lytic expansile radiolucency occupying the right mandibular body. An incisional biopsy of the right mandibular gingival mass was performed which revealed an unusual odontogenic neoplasm with mineralization and ghost cells. The patient was subsequently treated with excisional biopsy of the right mandibular lesion via enucleation and curettage. The specimen was sent to pathology and the tumor was found to have an epithelial neoplastic proliferation resembling that of ameloblastoma, accompanied by foci of ghost cells. Since mandibular bone was involved, a diagnosis of a benign central DGCT with extension into the overlying gingiva was rendered. She was successfully treated with excisional biopsy via enucleation and curettage and has no evidence of recurrence at three years post-operatively. DGCT can exhibit locally aggressive behavior and is characterized by ameloblastoma-like epithelial cells and the presence of dentinoid material and ghost cells., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

BACKGROUND Dentinogenic ghost cell tumor (DGCT) is a rare, locally invasive odontogenic neoplasm, considered as a solid variant of the calcifying odontogenic cyst (COC). DGCT accounts for only 2% to 14% of all COCs and less than 0.5% of all odontogenic tumors. It is characterized by an ameloblastomatous odontogenic epithelium and the presence of ghost cells and dentinoid material. CASE REPORT A 42-year-old male patient presented to the clinic with recurrent pain and swelling in the left maxilla. The patient had a similar presentation 3 years before, which had been managed by excisional biopsy and was misdiagnosed as unicystic ameloblastoma. Examination revealed a mild swelling in the left cheek with boney expansion on the posterior area of the left maxilla, with mobility in adjacent teeth. Radiographic evaluation revealed a large, well-demarcated radiolucent lesion with a sclerotic border involving the left maxilla and associated with root resorption in the adjacent teeth. An incisional biopsy was performed, and a diagnosis of DGCT was made. Segmental maxillectomy with safe margins was conducted, considering the aggressiveness of this pathological entity. The defect was reconstructed using the buccal fat pad. Histopathology examination confirmed the diagnosis of DGCT, which was characterized by ameloblastomatous odontogenic epithelium, dentinoid material, and ghost cells. One month follow-up revealed good healing of the surgical site. The patient was scheduled for regular follow-up. CONCLUSIONS This case reports the aggressiveness and high recurrence rates of DGCT. It is recommended to treat DGCT aggressively with safe margins and a long-term follow-up.

This case series describes the clinical appearance, radiographic appearance and histopathologic features of 4 patients (3 cats and 1 dog) with unique cystic oral lesions that are consistent with a diagnosis of calcifying odontogenic cyst (COC). COC is a rare odontogenic lesion in humans that has not been previously reported in companion animals. Historically, COC in humans has been classified as a benign cystic neoplasm and as a non-neoplastic odontogenic cyst. Current classification favors the latter. The cases in this series also have ambiguous features regarding classification of the lesion as an odontogenic cyst versus benign neoplasia.

The objectives of the present study were to comprehensively evaluate all the published cases on compound odontoma associated with calcifying odontogenic cyst (COaCOC) in the English literature and to describe the clinical, imaging and therapeutic variables for this condition. In August 2020, an electronic search of the PubMed / MEDLINE, Web of Science, ScienceDirect, Springer, and Scopus databases was carried out. The eligibility criteria included publications with enough information to confirm the diagnosis. Furthermore, we present a clinical case of a 16-year-old male patient with OCCaC, who was treated with enucleation, obtaining favorable and functional results. A total of 32 cases reported in the literature that met the inclusion and exclusion criteria, including ours, were analyzed and discussed. The mayority of the patients were women (n = 17) with an average age of 14.4 years, the maxilla was the most affected bone (n = 22) and the maxillary anterior region was the area with the highest number of cases (n = 18), the main clinical presentations were the volume increase (n = 14) and asymptomatic (n = 14). The choice treatment was enucleation (n = 26) and, in most cases, no recurrence was reported (n = 20). This study allows to update the characteristics of the OCCaC, giving an effective vision of how to treat this rare pathological association made up of two conditions that are completely different from each other., Competing Interests: Conflict of interests The authors inform that they have no conflict of interest., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Ghost cell odontogenic carcinoma (GCOC) is a rare malignant neoplasm, representing 3% of all ghost cell lesions of the jaws. They can arise de novo or from a pre-existing calcifying odontogenic cyst (COC) or dentinogenic ghost cell tumour (DGCT). A systematic review of the literature reported only 12 cases of a GCOC arising from a pre-existing COC. This report highlights an additional case of a GCOC arising from a pre-existing COC after 3 years in an adolescent male. The patient initially presented with a painless swelling of the right mandibular corpus. Panoramic radiographic examination showed an expansive unilocular radiolucent lesion. After 3 years, the radiographic features appeared more aggressive with increased expansion and cortical perforation. A wide surgical resection was performed, whereby the lesion was diagnosed as a GCOC. Due to the rarity of these malignant neoplasms, limited information is available regarding their biological behaviour. One-year follow-up revealed no clinical signs of recurrence.

The calcifying odontogenic cyst is as a benign, rare developmental odontogenic cyst with a wide range of histologic characteristics. It may present along with other odontogenic pathologies such as odontoma, ameloblastoma, adenomatoid odontogenic tumor, ameloblastic fibroma, and ameloblastic fibro-odontoma. Clinically, it can be an either intra- or extraosseous painless swelling that can produce cortical expansion. It affects mostly the anterior area of the mandible. Radiographically, it appears as a well-circumscribed unilocular radiolucency containing flecks of indistinct radiopacities. In about one third of cases, an impacted tooth is associated. In this paper, we employ a patient with an enormous calcifying odontogenic cyst to review both the pathology and active decompression and distraction sugosteogenesis, a novel technique employed to treat odontogenic entities. This dual approach usually results in an accelerated bone healing (sugosteogenesis), partial removal of the cystic epithelium, thickening of the wall, and migration of chronic inflammatory cells which triggered epithelial modulation, ultimately causing a realignment in the biologic behavior of the lesion.

Calcifying odontogenic cyst (COC) is a rare odontogenic cyst with ameloblastic epithelial lining containing clusters of ghost cells. COCs have been described in association with several odontogenic tumors, more commonly odontomas and rarely with dentigerous cyst (DC). In this article, we describe a case of COC associated with DC in a 15-year-old girl, who presented with a swelling on the right middle third of the face, producing facial asymmetry. Panoramic radiography showed a well-circumscribed, corticated, and unilocular radiolucency at the level of the right maxillary sinus, involving 2 unerupted premolars. The lesion was enucleated and histologically revealed a COC associated with DC, which presented mucous metaplasia. Immunohistochemical reactions were performed to better illustrate this rare synchronous occurrence of COC and DC, showing positivity for CK5, CK14, CK19, and p63 in both lesions. CK18 was negative in COC, and Bcl-2 was negative in DC. Periodic acid Schiff highlighted the mucous cells in the DC lining.

Background: The aim of this study was to integrate the available data published on calcifying odontogenic cyst (COC), dentinogenic ghost cell tumor (DGCT), and ghost cell odontogenic carcinomas (GCOCs) into a comprehensive analysis of their clinicoradiological features, treatment, and recurrence., Materials and Methods: An electronic search with no publication date restriction was undertaken in October 2017 in the following databases: PubMed, Medline Ovid, Web of Science, and Scopus. Eligibility criteria included publications containing enough clinical, radiological, and histopathological information to confirm a definite diagnosis of these lesions. Data were evaluated descriptively., Results: The literature review indicated a total of 234 publications reporting 367 COCs, 55 DGCTs and 44 GCOCs. These lesions have a predilection for Asian males. COCs mainly affect the mandible and patients in the second decade of life, DGCTs mostly affect the mandible and patients in the fourth decade of life, and GCOCs mostly affect the maxilla and patients in the fifth decade of life., Conclusion: Conservative surgery was the most common therapy for COCs and DGCTs, while radical surgery was most common for GCOCs. This study provides important and interesting data that could help clinicians and surgeons as well as oral and maxillofacial pathologists with the diagnosis and management of these lesions., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The calcifying odontogenic cyst is a rare developmental odontogenic lesion with a distinguishing cystic lining containing "ghost" epithelial cells. The variation in clinical, radiographic, and histologic findings makes the treatment decision difficult for these lesions. There are very few reports on treatment, with enucleation and curettage being the standard surgical method of choice for the cystic type and excision of the tumor for the solid type. A 2-stage surgical approach consisting of initial decompression with tube placement followed by a secondary procedure of enucleation and curettage is common for other large odontogenic cysts, such as dentigerous and odontogenic keratocysts. To the authors' knowledge, this is the first case managed with an intended 2-stage approach in the form of decompression followed by enucleation and curettage., (Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Ghost cell tumors are a family of lesions that range in presentation from cyst to solid neoplasm and in behavior from benign to locally aggressive or metastatic. All are characterized by the presence of ameloblastic epithelium, ghost cells, and calcifications. This report presents the cases of a 14-year-old girl with a calcifying cystic odontogenic tumor (CCOT) and a 65-year-old woman with a peripheral dentinogenic ghost cell tumor (DGCT) with dysplastic changes, a rare locally invasive tumor of odontogenic epithelium. The first patient presented with a 1-year history of slowly progressing pain and swelling at the left body of the mandible. Initial panoramic radiograph displayed a mixed radiolucent and radiopaque lesion. An incisional biopsy yielded a diagnosis of CCOT. Decompression of the mass was completed; after 3 months, it was enucleated and immediately grafted with bone harvested from the anterior iliac crest. The second patient presented with a 3-month history of slowly progressing pain and swelling at the left body of the mandible. Initial panoramic radiograph depicted a mixed radiolucent and radiopaque lesion with saucerization of the buccal mandibular cortex. An incisional biopsy examination suggested a diagnosis of DGCT because of the presence of ghost cells, dentinoid, and islands of ameloblastic epithelium. Excision of the mass with peripheral ostectomy was completed. At 6 and 12 months of follow-up, no evidence of recurrence was noted., (Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Introduction: Calcifying odontogenic cysts (COC) represent 0.3-0.8% of all odontogenic cysts. We describe the finding and the treatment of a COC in a 67-year-old female., Observation: An asymptomatic well-limited radioluscent mandibular lesion was fortuitously discovered on the panoramic X-ray in the periapical region of teeth No. 33 and 34. Treatment consisted in enucleation and curettage. Histologic examination was in favour of a COC. At 6 years follow-up, X-ray control showed new bone formation and the patient was free of symptoms. Pulp vitality was maintained in all teeth in the operated area., Discussion: Total enucleation is the preferred treatment of COC. Absence of recurrence is attested by X-ray controls and pulp vitality tests., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

An 18-year-old female reported painful swelling in the left maxillary region 4 months after the extraction of tooth #15. Because incisional biopsy suggested ameloblastoma with clear-cell changes, segmental resection was performed. The microscopic examination of the excised tissue revealed histomorphologic diversity, with features of typical calcifying ghost cell odontogenic tumor (CGCOT) and a significant clear-cell component constituting more than 50% of the tumor mass without any features of malignancy. Clear cells were periodic acid-Schiff (PAS) positive and mucicarmine negative. CK19 was strongly positive in the solid tumor islands and variably positive in clear cells. A definitive diagnosis of CGCOT with predominance of clear cells was confirmed. Because both squamous metaplasia and clear-cell components were present in the ameloblastic follicles independent of each other, the presence of abundant calcifications favored the diagnosis of CGCOT with a clear-cell component over that of an ameloblastoma with clear-cell changes. The importance of identifying the histomorphologic features of the 2 entities, ameloblastoma and CGCOT, is highlighted. This appears to be the second case reported in the literature, to the best of our knowledge., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Calcifying odontogenic cyst is a rare entity which was first described by Gorlin, and also accounts for 1% of the jaw cysts according to Shear. Due to its diverse histopathology and variable clinical features, there has been a doubt regarding its nature as a cyst or a neoplasm. In this report we present a case of calcifying odontogenic cyst with mural ameloblastomatous presentation in the left body of the mandible in a 19-year-old male patient. This is the 15th case of ameloblastomatous COC being documented in literature.

The calcifying epithelial odontogenic tumor (CEOT) is a benign tumor entity, usually localized in the molar region of the lower jaw. CEOT is not known for a destructive growth pattern, nevertheless it grows expansive. To properly diagnose a CEOT, histological verification is necessary. Due to its rare appearance and low incidence (approximately 4 cases per year worldwide), it is usually not diagnosed or thought of at once. Usually it happens to be the "surprising" diagnosis after histological verification. Hereby, we represent a case report of a CEOT - also known as "pindborg" tumor, and discuss the most likely differential diagnoses.

A calcifying cystic odontogenic tumor (CCOT) is an uncommon odontogenic tumor with a predilection for the anterior part of the jaws. We report on 2 cases of CCOT in the posterior maxilla involving the maxillary sinus. In the first case, conventional radiography found a well-defined unilocular lesion. Internal calcification was identified on cone beam computed tomography (CBCT) images. Radiographically, the second case showed 2 large locules with a large complex odontoma and an embedded third molar. By revealing the internal calcification of the lesion, CBCT was helpful in the differential diagnosis of the first case. In both cases, CBCT illustrated the tumor extension and the relationship of the tumor to the maxillary sinus. Therefore, CBCT was an important tool for developing effective treatment plans for lesions in the posterior maxillary region., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Introduction: Radiographic images may lead to misinterpretations of lesions of endodontic and nonendodontic origin. This report describes a case of a 10-year follow-up of a calcifying odontogenic cyst (COC) in the periapical region of a vital maxillary central incisor in a 9-year-old boy., Methods: The patient revealed a history of a swelling in the periapical area of tooth #9. The patient denied any dental trauma or history of pain. Clinical examination revealed no mobility, but there was discrete discomfort when horizontal pressure was applied. Pulp vitality was present in all maxillary anterior teeth. Radiographs revealed an oval radiolucent lesion in the periapical region of maxillary central incisor. The therapeutic option was enucleation of the periapical lesion and histologic examination of the specimen. Microscopic findings suggested the diagnosis of a COC., Results: At a follow-up visit 10 years after surgery, panoramic and periapical radiographs showed new bone formation; the patient did not have any pain, and pulp vitality was maintained in all teeth in this area., Conclusions: A COC should be part of the differential diagnosis of other jaw lesions, such as apical periodontitis. The definitive diagnosis of a COC can only be made after microscopic evaluation of the specimen. The follow-up is a helpful reference because it confirms the survival of pulp tissue and no recurrence of the COC., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Calcifying cystic odontogenic tumor (CCOT) is a rare histologic subtype of odontogenic tumor. Treatment requires complete enucleation. We report what we believe is the first case of CCOT to be removed via a transnasal endoscopic approach. A 16-year-old boy was referred to our department by his dentist for evaluation of an expansile mass of the left maxillary sinus. The dentist had noted an area of hyperlucency of the left palate during a routine examination. Computed tomography confirmed the presence of a large tumor. Complete resection of the tumor was achieved via a transnasal endoscopic surgical approach. Resection of odontogenic tumors is necessary because of their tendency to expand and produce a mass effect on surrounding structures. We believe resection via an entirely transnasal endoscopic approach is a valuable and important technique in the treatment of odontogenic tumors that leaves the patient with a more cosmetically acceptable postoperative appearance.

In this short communication, the very rare glandular odontogenic cyst (GOC) is presented as an independent entity. The GOC is a jawbone cyst of the maxilla and mandible. The typical radiological and histopathological characteristics of the GOC are described. Furthermore, differential diagnoses, current treatment options and the recurrence rates of this of entity are discussed.

Orthokeratinised odontogenic cyst (OOC) denotes the odontogenic cyst that microscopically has an orthokeratinised epithelial lining. OOC is characterised by a less-aggressive behaviour and a low rate of recurrence. This report describes a case of OOC involving posterior part of the mandible that mimicked periapical cyst in a 14-year-old boy. The initial clinical diagnosis was given as periapical cyst based on the clinical and radiographical features. Enucleation of the cyst was performed and the specimen was sent for histopathological examination. A definite diagnosis of OOC was made by histopathological examination of the biopsy specimen. This case emphases on including OOC in the differential diagnosis of radiolucencies occurring in the periapical region of non-vital tooth.

Calcifying epithelial odontogenic cyst (CEOC) is an odontogenic cyst with epithelial lining. CEOC is a rare entity that occurs in a wide age range, does not show any gender predilection, and accounts for only 1% of all jaw cysts. The lesion generally occurs in the region anterior to maxillary and mandibular molars and either intraosseously or extraosseusly. This entity might present as a cystic or solid lesion. Enucleation is the recommended treatment for a simple, unicystic CEOC. A case of recurring CEOC in the right maxilla antrum is presented here. The patient presented to the authors after postsurgical recurrence. The case was evaluated thoroughly, and the cyst was resolved.

Introduction: Keratocystic odontogenic tumor (KCOT) is defined as a benign cystic neoplasm of the jaws of odontogenic origin with a high rate of recurrence. The most lesions occur in the posterior part of the mandible. Treatment of KCOT remains controversial, but the goals of treatment should involve eliminating the potential for recurrence while minimizing surgical morbidity. However, another significant therapeutic problem related to the management of KCOT is an adequate and early reconstruction of the existing jaw defect, as well as appropriate aesthetic and functional rehabilitation of a patient, especially in cases of a very large destruction of the jaws bone., Case Report: We presented a 65-year-old female patient with very large KCOT of the mandible. Orthopantomographic radiography showed a very large elliptical multilocular radiolucency, located on the right side of the mandible body and the ascending ramus of the mandible, with radiographic evidence of cortical perforation at the anterior border of the mandibular ramus and the superior border of the alveolar part of the mandible. The surgical treatment included two phases. In the first phase, the tumor was removed by enucleation and additional use of Carnoy solution, performing peripheral ostectomy and excision of the affected overlying mucosa, while in the second phase, restorative surgery of the existing mandibular defect was performed 6 months later. Postoperatively, we did not register any of postoperative complications, nor recurrence within 2 years of the follow-up., Conclusion: Adequate and early reconstruction of the existing jaw defect and appropriate aesthetic and functional rehabilitation of the patient should be the primary goal in the treatment of KCOT, having in mind the need for a long-term post-surgical follow-up.

The calcifying cystic odontogenic tumor or Gorlin cyst is an uncommon lesion with a variable clinical behavior and considerable histopathologic diversity. The authors report a case of calcifying cystic odontogenic tumor that was being treated as a maxillary sinus mucocele. The possibility of mimicking numerous odontogenic and nonodontogenic lesions makes the calcifying cystic odontogenic tumor difficult for a clinical diagnosis. The present case demonstrates that a specific knowledge in oral pathology is required to differentiate odontogenic lesions.

Background: Initially described by Gorlin et al. in 1962, the calcifying cystic odontogenic tumor (CCOT) may be associated with unerupted teeth, ameloblastomas, adenomatoid odontogenic tumors, and, in many cases, with odontomas. It is rare in patients in the first decade of life, particularly involving deciduous teeth. Surgery is the treatment of choice, with low recurrence rates., Case Report: We present a clinical case of CCOT associated with odontoma and a missing deciduous tooth in a 3-year-old female patient. The lesion was removed under general anesthesia. The patient has been followed up for 1 year, and no recurrence was found. This appears to be the first report in such a young age.

Calcifying epithelial odontogenic tumor is a rare lesion. We report the imaging features of a calcifying epithelial odontogenic tumor. The imaging including conventional radiograph, CT and MR imaging revealed a well-defined lesion in the alveolar bone of the left maxilla, which contained an impacted tooth and some small radiopacities. CT and MR imaging demonstrated a contrast enhancement mainly at the central portion of the lesion.

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.

The aim of this study was to describe the clinicopathologic features of 177 keratocystic odontogenic tumors (KCOTs) diagnosed in a Brazilian population. A total of 177 KCOTs were reviewed and affected 158 patients with ages ranging from 5 to 79 years (mean age = 32 years) with a slight female predominance. Mandible was the most common affected site (69.3%), and a unilocular radiolucency was the most common radiographic image. Microscopically, all cases showed at least focal areas of classic KCOT, but several histological aspects were also observed, including diffuse and focal epithelial lining hyperplasia (48.6%), epithelial budding (12.4%), reactive cytological alterations (11.3%), dystrophic calcification (7.9%), daughter cysts (7.8%), odontogenic epithelial remnants (4.5%), focal areas of orthokeratinization (2.8%), and ameloblastomatous epithelium (1.7%). These variations may make KCOT diagnosis challenging in some cases, so careful full-sample analysis and knowledge of these uncommon histological features associated with KCOT are essential for correct diagnosis.

BACKGROUND. Peripheral (extraosseous) odontogenic tumors are rare. CASE REPORT. This report describes a case which illustrates the clinical and histopathological features of a lesion in an 8-year-old, healthy Caucasian girl that on purely morphological grounds would seem to be an ameloblastic fibro-odontoma, but may represent a case of a peripheral developing complex odontoma. CONCLUSION. Conservative surgical enucleation of the lesion was followed by unbcomplicated healing and no recurrence was seen., (© 2011 The Authors. International Journal of Paediatric Dentistry © 2011 BSPD, IAPD and Blackwell Publishing Ltd.)

Hybrid odontogenic tumors are rare conditions that can affect the oral maxillofacial region and usually occur in adults as an asymptomatic swelling. Hybrid odontogenic tumors exclusively involving adenomatoid odontogenic tumor (AOT) and calcifying cystic odontogenic tumor (CCOT) are rare, with only 4 reported cases. In addition, there are only few studies describing the presence of abortive enamel in AOT and, to our knowledge, CCOT was not present in any of them. We described a rare case of AOT associated with CCOT and abortive enamel formation in a 2-year-old child, a condition not well described in the international literature. Secretory cell activity was assessed by periodic acid-Schiff and Congo red stains.

A 38-year-old male presented with a slowly growing mass of the right mandible. The lesion displaced the mandibular canine and premolar teeth on the same side.

Calcifying odontogenic cyst is a rare lesion representing about 1% of jaw cysts. It may occur in a central (intraosseous) or peripheral (extraosseous) location. A case of peripheral calcifying odontogenic cyst located on the gingiva, appearing as a painless, circumscribed, sessile, and pink to red nodule has been reported.Peripheral, in contrast to central, calcifying odontogenic cyst tends to affect older patients. Peripheral calcifying odontogenic cyst is a less aggressive lesion than the central counterpart, and a simple excision biopsy is curative. The histologic findings of an epithelium rich in ghost cells has helped in making the diagnosis.

Odontogenic tumors composed of two or more distinct types of lesions are unusual. In this paper, a case of an odontogenic lesion characterized by simultaneous occurrence of areas of calcifying odontogenic cyst (COC) and orthokeratinized odontogenic cyst (OOC) is described. The lesion was asymptomatic and presented at the radiographic examination as a unilocular well-delimited radiolucency extending from left incisor to right premolar area in the mandible. To date, this is the first report of COC associated with an OOC.

The calcifying cystic odontogenic tumor is a rare benign odontogenic lesion. This report documents a case of this lesion associated with odontoma arising from the anterior maxilla in a 14-year-old boy. The diagnosis was confirmed based on computerized tomography findings, which clearly depicted the internal structures obscured in conventional images.

We describe a case of CEOT of the mandible, which underwent malignant transformation and developed metastatic tumors of the lung after repeated local recurrence. The primary tumor revealed typical histological features of benign CEOT showing sheets of polyhedral epithelial cells associated with abundant eosinophilic amyloid-like materials. On the other hand, the locally recurrent tumors had malignant features, such as increased nuclear pleomorphism with frequent mitotic figures and vascular invasion of tumor cells, as well as increased proliferative activity assessed by immunostaining for Ki-67. Chemotherapy was carried out against the pulmonary metastatic lesions, which showed a drastic response after 3 courses of intravenous administration of cisplatin (CDDP). To date, a total of 6 courses of CDDP and 6 courses of nedaplatin (CDGP) have been done, and the remaining pulmonary tumors have been dormant. This suggests that platinum derivatives could be a chemotherapeutic agent of choice against this rare tumor.