Calcifying Odontogenic Cyst Demonstrates Recurrent WNT Pathway Mutations and So-Called Adenoid Ameloblastoma-Like Histology: Evidence Supporting Its Classification as a Neoplasm.

Calcifying odontogenic cyst (COC), once called calcifying cystic odontogenic tumor, is classified under the category of odontogenic cysts. However, the proliferative capacity of the lesional epithelium and consistent nuclear ß-catenin expression raise questions about its current classification. This study aimed to determine whether COC would be better classified as a neoplasm in the histologic and molecular context. Eleven odontogenic lesions diagnosed as COC or calcifying cystic odontogenic tumor were included in this study. The growth patterns of the lesional epithelium were analyzed histologically in all cases. ß-catenin immunohistochemistry and molecular profiling using Sanger sequencing and whole-exome sequencing were performed in 10 cases. Of the 11 cases studied, histologic features reminiscent of so-called adenoid ameloblastoma were observed in 72.7% (8/11), and small islands of clear cells extended into the wall in 36.4% (4/11). Intraluminal and/or mural epithelial proliferation was found in 72.7% of the cases (8/11). Nuclear ß-catenin expression was observed focally in all 10 cases studied, mainly highlighting epithelial cells forming morules and adjacent to dentinoid. CTNNB1 hotspot mutations were detected in 60.0% of the cases (6/10). All the remaining cases had frameshift mutations in tumor-suppressor genes involved in the WNT pathway, including APC and NEDD4L. Recurrent WNT pathway mutations leading to nuclear translocation of ß-catenin and distinct epithelial growth patterns found in COC are the neoplastic features shared by its solid counterpart, dentinogenic ghost cell tumor, supporting its classification as a tumor rather than a cyst.

[Three-dimensional radiographic features of calcifying odontogenic cyst and calcifying epithelial odontogenic tumor].

OBJECTIVE: To analyze the three-dimensional radiographic characteristics of calcifying odontogenic cyst and calcifying epithelial odontogenic tumor using spiral computed tomography (CT) and cone-beam computed tomography (CBCT). METHODS: Clinical records, histopathological reports, and CBCT or non-enhanced spiral CT images of 19 consecutive patients with calcifying odontogenic cyst (COC) and 16 consecutive patients with calcifying epithelial odontogenic tumor (CEOT) were retrospectively acquired, and radiographic features, including location, size, expansion, internal structure and calcification, were analyzed. RESULTS: Among the 19 COC cases (12 males and 7 females, with an average age of 27 years), 89.5% (17/19) of the lesions originated from the anterior and premolar areas, 100.0% of them exhibited cortex expansion, and 78.9% had discontinued cortex. Among the 16 CEOT cases (3 males and 13 females, with an average age of 36 years), 81.3% (13/16) of the lesions were in the premolar and molar areas, 56.3% of them exhibited cortex expansion, and 96.8% had discontinued cortex. According to the distribution of internal calcifications, these lesions were divided into: Ⅰ (non-calcification type): absence of calcification; Ⅱ (eccentric marginal type): multiple calcifications scattered along one side of the lesion; Ⅲ (diffused type): numerous calcifications diffusely distributed into the lesion; Ⅳ (plaque type): with a ≥ 5 mm calcified patch; Ⅴ (peri-coronal type): multiple calcifications clustered around impacted teeth. Calcifications were present in 73.7% of COC lesions, including 9 type Ⅱ, 3 type Ⅲ and 2 type Ⅳ lesions, and 42.8% of CEOT lesions had calcification images, including 2 type Ⅲ and 5 type Ⅴ lesions. Six COC lesions had odontoma-like images. Moreover, 8 of 9 type Ⅰ CEOTs were histologically Langerhans cell-rich subtype, which had a smaller size (with an average mesiodistal diameter of 17.8 mm) and were not associated with impacted teeth. CONCLUSION: COC lesions tended to originate from the anterior part of the jaw and exhibit cortex expansion, and were sometimes associated with odontoma. CEOT commonly occurred in the posterior jaw and had discontinued cortex. Two lesions had significantly different calcification map. Over 70% of COC lesions had calcification images, which were mostly scattered along one side of the cysts, far from the impacted teeth. Approximately 60% of CEOT lesions exhibited smaller size and non-calcification, and the remaining CEOT cases often had calcification images clustered around the impacted teeth.

Primordial odontogenic tumor occurred in the maxilla with unique calcifications and its crucial points for differential diagnosis.

Primordial odontogenic tumor (POT) is a newly classified, mixed epithelial and mesenchymal odontogenic tumor, with only 17 reported cases to date. Herein, we report a case of POT that occurred in the right maxilla of a 10-year-old boy and reveal unique features in comparison with those previously reported. Radiologically, the lesion presented as a well-defined, unilocular radiolucency with notable radiopaque foci on the periphery. Microscopically, the tumor was mainly composed of dental papilla-like myxoid fibrous connective tissue, largely surrounded by non-keratinized squamous epithelium with numerous calcified particles, and partly enclosed by inner enamel epithelium-like columnar cells and enamel organ-like structures accompanied with cuboidal and/or stellate reticulum-like cells. Immunohistochemically, the epithelium tested positive for cytokeratin 14 and 19. Moreover, amelogenin and ameloblastin, matrix proteins relating to enamel formation, were positive in the covering epithelium. The tumor was enucleated as a whole, and no recurrence was recorded thereafter. Although the presence of numerous calcified particles was unique, we diagnosed this lesion as POT based on the above-described features. Furthermore, we emphasize the importance of the differential diagnosis of POT and other odontogenic tumors that resemble corresponding tooth germ components.

A lesion categorized between ghost cell odontogenic carcinoma and dentinogenic ghost cell tumor with CTNNB1 mutation.

Ghost cell odontogenic carcinoma (GCOC) is a rare malignant neoplasm characterized by the presence of ghost cells. It is considered to arise either de novo or from a preexisting benign precursor, calcifying odontogenic cyst (COC), or dentinogenic ghost cell tumor (DGCT). We report a case of a 44-year-old Japanese male with a left maxillary tumor. The patient received treatment to resect the left maxillary cyst 25 years prior; however, the details were uncertain. The tumor was resected with clear margins. Taken together with the results of histological and immunohistochemical examinations, the tumor was categorized between GCOC and DGCT, and we diagnosed the tumor as GCOC suggesting similarity to DGCT. Further, we focused on CTNNB1, which encodes ß-catenin and is frequently mutated in COCs. In this tumor, we identified CTNNB1 Ser33Cys, one of the mutations typically found in COCs. This finding suggests that CTNNB1 is a common target for the pathogenesis of tumors accompanied by ghost cells.

A multicentre study of 268 cases of calcifying odontogenic cysts and a literature review.

OBJECTIVES: To investigate the frequency of calcifying odontogenic cysts (COCs) that have been submitted for microscopic examination from representative geographic regions of Brazil and to compare it with literature data. MATERIALS AND METHODS: A retrospective study was conducted on biopsies obtained from 1953 to 2016 at 10 Brazilian oral and maxillofacial pathology centres. A total of 198,350 biopsy specimens were analysed. Demographic data and histopathological diagnosis were evaluated descriptively and statistically. In addition, a literature review of case series was carried out in four electronic databases. RESULTS: A total of 268 cases of COC were surveyed, representing 0.1% of the oral lesions at the centres studied. Female patients in their second decade of life and the maxilla were more affected. The mean lesion size of symptomatic individuals was larger than that of cases without symptoms (p = 0.026). The literature review showed a higher frequency in Asia and Europe, mainly affecting men in the third decade of life. CONCLUSIONS: COC is a rare lesion. Novel data on the clinicopathological features of 268 cases have been added to the literature. Data regarding gender and age of the Brazilian patients reported herein contrast with findings of case series and retrospective studies reported elsewhere.

Calcifying epithelial odontogenic cyst.

OBJECTIVE: The Calcifying Odontogenic Cyst was first described as a distinct clinicopathologic entity by Gorlin and his colleagues in 1962. Gold (1963) chose a similar, but not identical term for the lesion, namely 'keratinizing and calcifying odontogenic cyst'. 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). The calcifying odontogenic cyst is not a common lesion; the dentinogenic ghost cell tumor is even less common and should be considered rare. The lesions have in common the peculiar abnormal keratinization of odontogenic and metrical (hair) epithelial cells that is termed 'ghost cell' or 'shadow cell' keratinization. A rare, well-circumscribed, solid or cystic lesion derived from odontogenic epithelium that resembles follicular ameloblastoma but contains 'ghost cells' and spherical calcifications. The so-called calcifying odontogenic cyst (COC) represents a heterogeneous group of lesions that exhibit a variety of clinicopathologic and behavioural features. Because of this diversity, there has been confusion and disagreement on the terminology and classification of these lesions. Here we present a classic case of Calcifying Odontogenic Cyst (COC) or Calcifying Cystic Odontogenic Tumor in a 37 years old male patient. which is provisionally diagnosed by means of clinical & radiographical findings and later on confirmed by histological examination.

Ghost Cell Tumors.

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.

Histologic Variants of Calcifying Odontogenic Cyst: A Study of 52 Cases.

AIM: This study aimed at evaluating histological features of 52 cases of calcifying odontogenic cyst (COC), which is an uncommon benign odontogenic lesion. The World Health Organization (WHO) classified COC as a neoplasm and used the term calcifying cystic odontogenic tumor (CCOT) for benign cystic type and the dentinogenic ghost cell tumor (DGCT) for the benign solid-type lesions. There is no agreement regarding COC classification. MATERIALS AND METHODS: A total of 52 cases of COC were selected and reviewed from the archive of the Pathology Department of Taleghani Educational Hospital, Tehran, Iran. To better understand the pathogenesis of COC, the cases were classified. RESULTS: There were 52 cases (31 males and 21 females). The lesion was found in all age groups, and patients' age from 8 to 61 years. Nineteen cases affected the maxilla, and 33 cases affected the mandible. Except two cases, all were intraosseous lesions. Radiographically, 30 cases showed a unilocular radiolucent area, and 22 cases showed a mixed radiolucent/ radiopaque region. Histopathologically, 43 cases were cystic type and 9 cases were neoplastic. CONCLUSION: There are two different histopathological entities. In view of these findings, it is very difficult to determine every lesion that has a cystic architecture is truly cystic or is a neoplastic one in nature. It is believed that the solid variants may be neoplastic. CLINICAL SIGNIFICANCE: A better understanding of the histological type of the lesion can provide a classification across patients. This can help in treatment planning to improve patient outcomes.

Peripheral calcifying cystic odontogenic tumour and peripheral dentinogenic ghost cell tumour: an updated systematic review of 117 cases reported in the literature.

PURPOSE: To integrate the available data published on peripheral calcifying cystic odontogenic tumour (CCOT) and peripheral dentinogenic ghost cell tumour (DGCT) into a comprehensive analysis of its clinical and radiologic features. METHODS: An electronic search was undertaken in May, 2016. Eligibility criteria included publications reporting cases of peripheral CCOTs/DGCTs having enough clinical, radiological and histological information to confirm a definite diagnosis. Demographic data, lesion site and size, treatment approach and recurrence were analyzed. RESULTS: Hundred and thirty-eight lesions were found (65 publications), and 117 lesions (63 publications) with enough information were analyzed (55 CCOTs, 50 DGCTs, 12 unknown). Mean age of patients was 51.3 ± 23.4 (min-max, 1-92), with higher mean age for the DGCTs variant. The lesions were more prevalent in the mandible, anterior region of the jaws, and in the second, sixth and eighth decades, with an equal sexual distribution. About 20% of all lesions showed signs of erosion of the underlying bone, with a higher rate for DGCTs. The mean lesion size was 1.3 ± 0.8 (min-max, 0.4-3.0). Time of follow-up was informed for 37 lesions, with a mean ± SD of 30.2 ± 21.0 months (min-max, 6-84). Almost all lesions were treated by conservative surgery; only three recurrences were reported. CONCLUSIONS: Peripheral CCOTs/DGCTs are rare lesions. Most of the lesions were treated by simple excision with or without curettage of the underlying bone. As the recurrence rate is very low, a conservative approach seems to be enough for the great majority of cases.

Ghost cells in pilomatrixoma, craniopharyngioma, and calcifying cystic odontogenic tumor: histological, immunohistochemical, and ultrastructural study.

BACKGROUND: Pilomatrixoma, craniopharyngioma, and calcifying cystic odontogenic tumor are the main entities presenting ghost cells as an important histological feature, in spite their quite different clinical presentation; it seems that they share a common pathway in the formation of these cells. The aim of this study is to examine and compare the characteristics of ghost and other cells that form these lesions. METHODS: Forty-three cases including 21 pilomatrixomas, 14 craniopharyngiomas, and eight calcifying cystic odontogenic tumors were evaluated by immunohistochemistry for cytokeratins, CD138, ß-catenin, D2-40, Glut-1, FAS, CD10 and also by scanning electron microscopy. RESULTS: The CKs, CD138, ß-catenin, Glut-1, FAS, and CD10 were more often expressed by transitional cells of craniopharyngioma and calcifying cystic odontogenic tumor, compared with pilomatrixoma. Basaloid cells of pilomatrixoma showed strong positivity for CD138 and CD10. Differences on expression pattern were identified in transitional and basal cells, as ghost cells were negative for most antibodies used, except by low expression for cytokeratins. By scanning electron microscopy, the morphology of ghost cells were similar in their fibrillar cytoplasm, but their pattern varied from sheets in pilomatrixoma to small clusters in craniopharyngioma and calcifying cystic odontogenic tumor. CONCLUSIONS: Mechanisms involved in formation of ghost cells are unknown, but probably they follow different pathways as protein expression in the basal/transitional cells was not uniform in the three tumors studied.

Calcifying cystic odontogenic tumor associated with ameloblastic fibro-odontoma of the anterior mandible.

Calcifying cystic odontogenic tumor, which was formerly named calcifying odontogenic cyst, is a benign odontogenic tumor containing clusters of ghost cells within ameloblastic epithelium. Calcifying cystic odontogenic tumors have been associated with other odontogenic tumors, a finding that is a rare event in other types of odontogenic cysts or tumors. This report describes a case of hybrid odontogenic tumor composed of calcifying cystic odontogenic tumor and ameloblastic fibroma-odontoma of the anterior mandible that occurred in a 4-year-old Korean girl.

Calcifying odontogenic cyst: dilemma in classification.

Calcifying odontogenic cyst (COC) shows extreme diversity in its clinical and histopathological features, as well as in its biological behavior. Because of this diversity, there has been confusion and disagreement on the terminology and classification of this lesion. Attempts to classify COC can be divided into two concepts: monistic and dualistic. We present a case of COC with coexisting histopathologic features of a cyst and a neoplasm, thus posing a dilemma in the terminology used to categorize and classify it.

Calcifying Odontogenic Cyst Presenting Odontogenic Keratocyst-Like Areas: A Rare Case Report.

An 81-year-old male patient presented with a well-demarcated, unilocular radiolucent lesion in the right mandibular body, identified during a routine radiographic examination. Based on the clinical hypothesis of a residual cyst, enucleation with curettage was performed, and the specimen was submitted for histopathological analysis. Microscopically, the cystic lesion was predominantly lined by ameloblastomatous epithelium with numerous ghost cells and dentinoid. Additionally, other cystic cavities lined by stratified squamous epithelium with corrugated parakeratin were observed in the fibrous capsule. Based on these features, a final diagnosis of a calcifying odontogenic cyst with odontogenic keratocyst-like areas was established. No recurrence was observed over a 9-year follow-up period. The association of a calcifying odontogenic cyst with odontogenic keratocyst or odontogenic keratocyst-like areas is very rare. To date, this is the second case report in the literature presenting these findings.

Epidemiology of odontogenic tumours and selected cysts diagnosed at a single New Zealand oral pathology centre- A 15-year retrospective study.

PURPOSE: This research aimed to investigate the relative frequency of odontogenic tumours (OT) and selected odontogenic cysts in a single oral pathology center in New Zealand from 2008 to 2023. METHODS: Histopathological records from the Oral Pathology Centre, University of Otago (2008-2023) were examined to identify OT. Odontogenic keratocyst (OKC) and calcifying odontogenic cyst (COC), previously classified as OT were also included. Patient demographics, clinical details and histopathologic diagnoses were recorded. Data were analyzed using SPSS. RESULTS: Of the 34,225 biopsies over the 15-year period, 1.8% were identified as OTs, COC and OKCs and accounted for 47%, 1.5% and 51.5% respectively. The most prevalent OT types were odontoma (43.7%), ameloblastoma (27%) and cemento-ossifying fibroma (7.5%). Malignant OT, ameloblastic carcinoma, constituted 1.4% of OT. The average age at diagnosis for OKC, COC and OT patients were 48.2 ± 20.9, 33.7 ± 23.3 and 28.9 ± 19.3 years. Overall, male and mandibular site predilections were observed. Recurrence of OKC and ameloblastoma occurred in 15.2% and 13.7% of patients. The time for recurrence for OKC and Ameloblastoma were 61.7 ± 56.5 months and 122 ± 152 months respectively. CONCLUSION: The demographic features and range of OT, COC and OKC in New Zealand align with those of other western countries. The study also confirms need for long term follow up for patient with OKC and ameloblastoma.

CD1a-positive Langerhans cells and their relationship with E-cadherin in ameloblastomas and keratocystic odontogenic tumors.

BACKGROUND: Ameloblastomas and keratocystic odontogenic tumors (KOTs) are lesions that are characterized by locally invasive growth and cause extensive bone destruction. In addition, it is known that E-cadherin influences the adhesion of Langerhans cells (LCs) to keratinocytes. OBJECTIVE AND METHODS: The aim of this study was to investigate, using immunohistochemistry, the distribution of CD1a-positive cells in ameloblastomas and KOTs and their relationship with E-cadherin, in comparison to calcifying cystic odontogenic tumor (CCOT). RESULTS: The CD1a-positive LCs were observed in 11 ameloblastomas and KOTs. All of the cases of CCOT showed CD1a-positive LCs and a significant difference was found when this tumor was compared with ameloblastomas (P < 0.05, Mann-Whitney test). A statistically significant difference was also noted when comparing CD1a-positive LCs between CCOTs and KOTs (P < 0.05, Mann-Whitney test). Lower expression of E-cadherin in ameloblastomas (AMs) in relation to KOTs and CCOTs (P < 0.05, Fisher test) was observed. There was no correlation between E-cadherin and CD1a-positive LCs between all odontogenic tumors that were studied (P > 0.05, Spearman test). CONCLUSION: A quantitative difference of CD1a-positive cells between AMs and KOTs in comparison to CCOTs was observed. This permits to speculate that a depletion of CD1a-positive LCs might influence the local invasiveness of ameloblastomas and KOTs. Furthermore, it is suggested that E-cadherin mediates cell adhesion in these tumors.

TGF-ß1, Smad-2/-3, Smad-1/-5/-8, and Smad-4 signaling factors are expressed in ameloblastomas, adenomatoid odontogenic tumors, and calcifying cystic odontogenic tumors: an immunohistochemical study.

OBJECTIVES: The TGF-ß/Smad signaling pathway regulates diverse cellular functions, including tooth development, and is involved in numerous pathological processes such as tumorigenesis. The aim of this study was to investigate the immunoexpression of the TGF-ß/Smad signaling pathway members in ameloblastoma (AM), calcifying cystic odontogenic tumor (CCOT), and adenomatoid odontogenic tumor (AOT). MATERIALS AND METHODS: This retrospective cross-sectional study included 65 tissue specimens: 34 AMs, 13 CCOTs, and 18 AOTs. Serial sections were immunohistochemically stained with TGF-ß1, Smad-4, Smad-1/-5/-8, and Smad-2/-3 antibodies, and a semiquantitative measurement of the positive cells was carried out by two oral pathologists using a 0-3 scale (0: no immunoreactivity, 1: <20% positive cells, 2: 20-50% positive cells, 3: >50% positive cells). RESULTS: All biomarkers studied were found significantly decreased in AM compared to CCOT and AOT. AOT and CCOT expressed Smad-1/-5/-8 more strongly compared to AM (OR = 11.66, P < 0.001 and OR = 5.34, P = 0.013, respectively), and Smad-2/-3 immunostaining was found significantly increased in CCOT (OR = 10.42, P = 0.001) and AOT (OR = 5.16, P < 0.004) compared to AM. Similarly, Smad-4 was expressed more strongly in AOT and CCOT compared to AM (P = 0.001), while AOT demonstrated a fivefold higher chance to express TGF-ß1 compared to AM (P = 0.011). CONCLUSION: TGF-ß/Smad signaling pathway is activated in AM, AOT, and CCOT. The statistically significant reduced TGF-ß1/Smad immunoexpression in AM compared to AOT/CCOT could be associated with the more aggressive biological behavior of AM including increased cell proliferation and reduced apoptosis and differentiation. Thus, the biomarkers TGF-ß, Smad-4, Smad-1/-5/-8, and Smad-2/-3 could serve as supplementary diagnostic indices between odontogenic tumors of high and low neoplastic dynamics.

Detection of cytokeratins in ghost cells of calcifying cystic odontogenic tumor indicates an altered keratinization and hair follicle differentiation for their development.

Calcifying cystic odontogenic tumors (CCOTs) are benign cystic lesions of odontogenic origin characterized by an ameloblastoma-like epithelium and the presence of a group of cells named ghost cells. The pattern of cytokeratin (Ck) expression on these lesions remains unclear and needs to be clarified. To this end, the expression of Ck6, Ck13, Ck14, Ck18, and Ck19 in the epithelium lining of 7 cases of CCOTs was evaluated by immunohistochemistry. For this, the epithelium lining was divided into 3 distinct regions: basal layer, suprabasal layer, and the compartment composed of ghost cells. In this study, 6 cases (85.7%) were classified as type 1 and 1 (14.3%) as type 4. All cases were negative for Ck13 and Ck18, despite the epithelial layer, as well as in the ghost cells. Ck6 was only positive in the ghost cells. Positivity for Ck14 and Ck19 was found in the basal and suprabasal layers, including the ghost cells. The results showing positivity for Ck14 and Ck19 in all of the analyzed cases reinforce CCOT as being of odontogenic origin, and the restricted expression of Ck6 in the ghost cells may be indicative that these cells suffer an altered differentiation into hair follicles in CCOTs.

Calcifying cystic odontogenic tumor radiographically mimicking a sinus mucocele.

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.

A rare case of recurring calcifying epithelial odontogenic cyst in the maxillary sinus: a case report and literature review.

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.

Calcifying odontogenic cyst: a rare report of a nonneoplastic variant associated with cholesterol granuloma.

AIM: To report a case of a non-neoplastic variant of calcifying odontogenic cyst (COC) with the lining epithelium showing ameloblastomatous proliferation and capsule exhibiting features of a cholesterol granuloma. The importance of delineating this histologic variant from unicystic ameloblastoma and the formation of cholesterol granuloma in this variant is discussed. BACKGROUND: Calcifying odontogenic cyst is a developmental jaw cyst, which presents itself as both the neoplastic and the non-neoplastic forms. The ameloblastomatous variant of COC is often mistaken for unicystic ameloblastoma and treated aggressively. CASE REPORT: A 68-year-old female who presented with a cystic enlargement of the posterior mandible on the right side was suggestive of unicystic ameloblastoma based on radiography and initial biopsy report. Microscopic examination of the excision specimen, however, was fitting in favor of calcifying odontogenic cyst with ameloblastomatous proliferation. CONCLUSION: Identifying the non-neoplastic ameloblastomatous variant of COC from a cystic ameloblastoma is crucial as the treatment of the two lesions vary considerably. CLINICAL SIGNIFICANCE: This case emphasizes the need for thorough examination of the entire surgical specimen before arriving at an appropriate diagnosis.