Primary Ameloblastoma Research Articles

Prognostic significance of MCM2high/Ki-67high in ameloblastoma

ObjectiveMinichromosome maintenance (MCM) protein 2 is critical for the beginning of DNA replication and is a notable marker for proliferating cells. The prognosis and management of ameloblastoma are based on histology and other factors. However, immunohistologic markers capable of detecting recurrence-prone ameloblastoma with a poor prognosis have not been adequately investigated. This study aimed to identify the association between MCM2 overexpression and recurrence prognosis and risk stratification. MethodsThirty-two patients who had been diagnosed with ameloblastoma at our department between January 1982 and December 2019 were included in this study. Thirty-two (fifteen follicular, ten plexiform, five unicystic, two desmoplastic) subtype cases were analyzed for immunohistochemical expressions of MCM2 and Ki-67. ResultsDisease-free survival (DFS) analysis revealed that patients with MCM2high/Ki-67high ameloblastoma had a significantly shorter median survival time (63 vs. 360 months) and lower DFS survival rate (50.0% vs. 90.0%) than those with MCM2low/Ki-67low (p = 0.003). Multivariate analysis revealed that a location (maxillary primary ameloblastoma) and MCM2high/Ki-67high were independent risk factors for DFS. ConclusionOur results identified MCM2high/Ki-67high ameloblastoma as a subgroup with poor recurrent prognosis and DFS. Ameloblastoma should be assessed using immunohistochemical staining. Our study revealed that tumors with a worse recurrent prognosis require appropriate clinical surveillance.

Identification of ferroptosis-related proteins in ameloblastoma based on proteomics analysis.

We used proteomic sequencing and experimental verification to identify the potential ferroptosis-related proteins in ameloblastoma. Samples of ameloblastoma (n = 14) and normal gingival tissues (n = 5) were collected for proteomic sequencing to identify differentially expressed proteins (DEPs) in ameloblastoma. Ferroptosis-related genes were downloaded from FerrDb V2, which were then compared with DEPs to obtain ferroptosis-related DEPs (FR-DEPs). A functional enrichment analysis was performed, and a protein-protein interaction network was built. The hub proteins were screened using the Cytoscape software, and potential drugs targeting them were retrieved from the DrugBank database. A hub protein was selected for immunohistochemical validation, and its expression was assessed in ameloblastomas, odontogenic keratocysts, dentigerous cysts, and normal gingival tissues. The primary ameloblastoma cells were cultured to explore the effect of the protein on the migratory properties of the tumour cells. A total of 58 FR-DEPs were screened, and six hub proteins were identified: mTOR, NFE2L2, PRKCA, STAT3, EGFR, and CDH1. Immunohistochemical analysis showed that mTOR expression was upregulated in ameloblastomas compared with that in odontogenic keratocysts, dentigerous cysts, and normal gingival tissues. p-mTOR was highly expressed in ameloblastomas, with a positivity rate of 83.3%. In addition, rapamycin, an inhibitor of mTOR, can inhibit the migratory capacity of primary cultured ameloblastoma cells. Our results revealed the ferroptosis-related proteins in ameloblastomas and their underlying biological processes. Additionally, mTOR was overexpressed and was found to be associated with the aggressiveness of ameloblastomas, which may be a potential target for future treatments.

Fluid aspirates of ameloblastoma

Background: Ameloblastoma is a benign cystic odontogenic tumor common in Nigeria. The cystic cavities frequently contain tumor fluids, which may be obtained by needle aspiration. The tumor fluids help in the clinical differential diagnosis. The types, prevalence, and relevance of ameloblastoma fluid aspirates have been mostly unreported. Objectives: The aim of this study was to identify the types and prevalence of fluid aspirates of ameloblastoma and evaluate its prognostic relevance. Materials and Methods: This was a 7-year retrospective study of consecutive patients with ameloblastoma at a tertiary hospital in Enugu, Nigeria. The tumor fluids obtained by needle aspiration are categorized based on visual appearance. The data retrieved from case files, biopsy forms, histopathologic reports, and other records in the departmental archives were analyzed with IBM SPSS Statistics, version 24.0. Results: Tumor fluid aspirate yield was positive in 80.4% ((n=74) of patients with ameloblastoma. There were aspirates from 82.4% (n=61) cases of primary ameloblastoma and 17.6% (n=13) cases of recurrent ameloblastoma. The aspirates obtained were dark-brown 41.9%, straw-colored 37.8%, serosanguinous 10.8%, and purulent 9.5%. The type of aspirate was influenced by the primary or recurrent status of ameloblastoma (P = 0.04). Straw-colored aspirate was obtained from 92.9% of primary ameloblastoma and in 73.1% of patients <20 years of age. Recurrent ameloblastoma typically yielded dark-brown aspirates in 76.9% of recurrences. Conclusion: The association of some tumor fluids with primary and recurrent ameloblastoma could improve the understanding of the recurrence potential of the disease and influence treatment planning.

Potential Biomarkers and Signaling Pathways Associated with the Pathogenesis of Primary Ameloblastoma: A Systems Biology Approach

Objective Ameloblastoma is a benign odontogenic tumor that may lead to ameloblastic carcinoma. This study aimed to determine potential signaling pathways and biological processes, critical genes and their regulating transcription factors (TFs), and miRNAs, as well as protein kinases involved in the etiology of primary ameloblastoma. Methods The dataset GSE132472 was obtained from the GEO database, and multivariate statistical analyses were applied to identify differentially expressed genes (DEGs) in primary ameloblastoma tissues compared to the corresponding normal gingiva samples. A protein-protein interaction (PPI) map was built using the STRING database. The Cytoscape software identified significant modules and the hub genes within the PPI network. Gene Ontology annotation and signaling pathway analyses were executed by employing the DAVID and Reactome databases, respectively. Significant TFs and miRNAs acting on the hub genes were identified using the iRegulon plugin and MiRWalk 2.0 database, respectively. A protein kinase enrichment analysis was conducted using the online Kinase Enrichment Analysis 2 (KEA2) web server. The approved drugs acting on the hub genes were also found. Results A total of 1,629 genes were differentially expressed in primary ameloblastoma (P value <0.01 and |Log2FC| > 1). HRAS, CDK1, MAPK3, ERBB2, COL1A1, CYCS, and BRCA1 demonstrated high degree and betweenness centralities in the PPI network. E2F4 was the most significant TF acting on the hub genes. BTK was the protein kinase significantly enriched by the TFs. Cholesterol biosynthesis was considerably involved in primary ameloblastoma. Conclusions This study provides an intuition into the potential mechanisms involved in the etiology of ameloblastoma.

FOSL1 promotes tumor growth and invasion in ameloblastoma.

BackgroundFOSL1, a key component of the Activating protein-1 (AP-1) transcriptional complex, plays an important role in cancer cell migration, invasion, and proliferation. However, the impact of FOSL1 in ameloblastoma (AM) has not been clarified. Herein, we aimed to assess the expression of FOSL1 and investigate its functional role in AM.MethodsThe expression of FOSL1 was examined based on an immunohistochemistry analysis of 96 AM samples. Cell proliferation, migration, invasion, and tumorigenesis were assessed using Cell Counting Kit-8 (CCK-8), colony formation, Transwell, and sphere formation assays. RNA sequencing (RNA-seq) was employed to investigate the molecular alterations of AM cells upon FOSL depletion. Microarrays of AMs were downloaded from the Gene Expression Omnibus (GEO) database for bioinformatics analysis. In addition, patient-derived AM organoids were used to evaluate the therapeutic value of the AP-1 inhibitor.ResultsFOSL1 was detected in the nuclei of AMs and upregulated in conventional AMs compared to unicystic AMs and normal oral epithelium. Compared with primary AM, FOSL1 expression was significantly increased in recurrent AM. Genetic knockdown of FOSL1 suppressed the proliferation, migration, invasion, and sphere formation of AMs. Similar results were also observed by pharmacological inhibition of AP-1 activity. Moreover, the AP-1 inhibitor T5224 impeded the growth of organoids derived from AM patients. Mechanistically, our Ingenuity Pathway Analysis (IPA) and gene set enrichment analysis (GSEA) results revealed that depletion of FOSL1 inactivated kinetochore metaphase signaling and the epithelial–mesenchymal transition pathway and then impaired the aggressiveness of AM cells accordingly.ConclusionFOSL1 promotes tumor recurrence and invasive growth in AM by modulating kinetochore metaphase signaling and the epithelial–mesenchymal transition pathway; thus, it represents a promising therapeutic target for AM treatment.

Immediate free flap reconstruction following the resection of benign jaw lesions: A 15-year perspective

ObjectivesTo report on outcomes of immediate free flap reconstruction following the resection of extensive benign jaw lesions. MethodsThis is a retrospective study on all patients who required free flap reconstruction after the ablation of benign jaw lesions and who were operated on by the Oral and Maxillofacial Surgery department in a tertiary care centre in Hong Kong from 2004 to 2019. The primary outcome assessed is flap success. The secondary outcomes assessed are recipient site, donor site and other complications, number of days on nasogastric tube and dental rehabilitation. Results45 patients were treated. Primary ameloblastoma was treated in 26 patients and recurrent ameloblastoma in five patients. 41 out of 45 cases were successful. The most common complication was local infection, experienced by 11.1 % of patients. On average, each patient spent 8.8 days on nasogastric tube feeding post-operatively. There was a significant difference in the number of days the patient was kept on nasogastric tube between the group which experienced recipient site complications and the group which did not (p = 0.0218). Dental rehabilitation with implants or dentures was possible in two-thirds of the patients. ConclusionImmediate free flap reconstruction is feasible for the reconstructing defects resulting from the resection of benign pathology, demonstrating high success and the option of dental rehabilitation. Age is not a significant factor in post-operative complications. Preventing recipient site complications may promote earlier resumption of oral feeding.

Alteration of primary cilia morphology and associated signalling in ameloblastoma

ObjectivesPrimary cilium is a cellular organelle with growing significance confirmed in tumour biology. Primary cilia have been associated with fine tuning of numerous cell signalling pathways and the role of this structure in cancer initiation and progression is recently at the forefront of attention. Here, we investigated possible alterations in the occurrence of primary cilia and changes of associated signalling in ameloblastoma, which represents the most common odontogenic tumour. MethodsWe performed immunohistochemistry to assess the number and morphology of primary cilia in ameloblastoma tissues. The gene expression of key SHH pathway members was analysed by qPCR. As a functional experiment, we treated a primary ameloblastoma cell line by a SHH pathway inhibitor Sonidegib (LDE225). ResultsWe uncovered differences in primary cilia distribution and appearance in histological subtypes of ameloblastoma with the highest number of ciliated cells in plexiform and follicular subtypes. SHH protein was located close to primary cilia in ameloblastoma epithelial cells and the expression of molecules downstream of SHH signalling was upregulated. Moreover, the inhibition of SHH pathway by Sonidegib caused downregulation of SHH effector gene GLI1 and cell cycle regulator CCND1 in ameloblastoma primary cell line. The inhibition of SHH signalling also altered the expression of molecules involved in intraflagellar transport. ConclusionsIn conclusion, our study uncovered alterations in number of ciliated cells and associated signalling in ameloblastoma, which indicate SHH inhibitors as potential therapeutic target to treat this disease.

Activation of Wnt signalling reduces the population of cancer stem cells in ameloblastoma.

ObjectivesThe treatment of ameloblastoma, an odontogenic epithelial tumour destroying jawbone, mainly depends on radical destructive resections. Other therapeutic options are limited by the characteristics of ameloblastoma, such as high recurrence rates and resistance to radiation and chemotherapy, which implies possible existence of cancer stem cells (CSCs) in ameloblastoma. Here, we identified a putative CSC population in immortalized and primary human ameloblastoma cells and examined possible therapeutic reagents to reduce the CSC population.MethodsWe investigated subpopulations of AM‐1 cell line and human ameloblastoma cells using immunocytochemistry and flow cytometry and the effects of Wnt signalling activators on the 2‐ and 3‐dimensional cultured ameloblastoma cells using molecular biological analyses.ResultAmong heterogenous ameloblastoma cells, small‐sized and round‐shaped cells were found to be proliferative and expressed a marker of dental epithelial stem cells, SRY‐box 2 (Sox2). Exogenous activation of Wnt signalling using glycogen synthase kinase 3β inhibitors, lithium chloride (LiCl) and valproic acid (VPA), increased the cell size and decreased proliferation of cells and expression of Sox2 in 2 dimensionally cultured AM‐1 and human primary ameloblastoma cells. Furthermore, the growth of 3 dimensionally cultured AM‐1 cells as suspended or embedded in gel was suppressed by treatment with Wnt signalling activators, VPA and CHIR99021, or antibodies to sclerostin, an antagonist of Wnt signalling.ConclusionWe suggest that Wnt signalling activators are potential drug candidates to suppress CSCs in ameloblastoma.

Recurrence Rate of Surgical Resection with Reconstruction of Plate Osteosynthesis in the Ameloblastoma Treatment

This study was conducted to treat patients with primary ameloblastoma and solid/multicystic ameloblastomahistopathologically. Twenty-seven patients with primary ameloblastoma were treated in the period between2008 and 2019 in the Department of Oral and Maxillofacial Surgery, and these patients ranged from 16y to 58 y old and the average age was 37 y. The number of males reached 16 individuals and the numberof females 11 individuals. Twenty-two patients with solid/multicystic ameloblastoma histopathologicallywere treated for partial jaw excision along with the restoration of bone plate osteosynthesis and 2 cm wasused to remove a surgical free margin with bone correction, and three patients with bone metastasis weretreated with excision, and the marginal jaw was removed with a 1 cm free margin with a reconstructivebone structure. Patients with unicystic ameloblastoma were treated through partial removal of the lower jawwith bone structure with titanium, and 1.5 cm was used as a free margin useful for bone health. There are3 patients out of twenty-two infected primary solid/multicystic ameloblastoma were present with cases ofrepeated visualization of radiation are sick after 7 y of surgery and during routine follow-up, one patient wasoffered during the 6 y after the operation.

Fluorescently Labeled Cetuximab-IRDye800 for Guided Surgical Excision of Ameloblastoma: A Proof of Principle Study

Fluorescently labeled epidermal growth factor receptor (EGFR) antibodies have successfully identified microscopic tumors in multiple invivo models of human cancers with limited toxicity. The present study sought to demonstrate the ability of fluorescently labeled anti-EGFR, cetuximab-IRDye800, to localize to ameloblastoma (AB) tumor cells invitro and invivo. EGFR expression in AB cells was confirmed by quantitative real-time polymerase chain reaction and immunohistochemistry. Primary AB cells were labeled invitro with cetuximab-IRDye800 or nonspecific IgG-IRDye800. An invivo patient-derived xenograft (PDX) model of AB was developed. The tumor tissue from 3 patients was implanted subcutaneously into immunocompromised mice. The mice received an intravenous injection of cetuximab-IRDye800 or IgG-IRDye800 and underwent imaging to detect infrared fluorescence using a Pearl imaging system (LI-COR Biosciences, Lincoln, NE). After resection of the overlying skin, the tumor/background ratios (TBRs) were calculated and statistically analyzed using a paired t test. EGFR expression was seen in all AB samples. Tumor-specific labeling was achieved, as evidenced by a positive fluorescence signal from cetuximab-IRDye800 binding to AB cells, with little staining seen in the negative controls treated with IgG-IRDye800. In the animal PDX model, imaging revealed that the TBRs produced by cetuximab were significantly greater than those produced by IgG on days 7 to 14 for AB-20 tumors. After skin flap removal to simulate a preresection state, the TBRs increased with cetuximab and were significantly greater than the TBRs with the IgG control for PDX tumors derived from the 3 patients with AB. The excised tissues were embedded in paraffin and examined to confirm the presence of tumor. Fluorescently labeled anti-EGFR demonstrated specificity for AB cells and PDX tumors. The present study is the first report of tumor-specific, antibody-based imaging of odontogenic tumors, of which AB is one of the most clinically aggressive. We expect this technology will ultimately assist surgeons treating AB by helping to accurately assess the tumor margins during surgery, leading to improved long-term local tumor control and less surgical morbidity.

Investigation of PTEN promoter methylation in ameloblastoma

Background Phosphatase and tensin homolog (PTEN) acts as a tumor suppressor gene. Inactivation of PTEN has been reported in various types of cancers. PTEN promoter methylation possibly underlies PTEN inactivation, which results in tumorigenesis. The aim of this study was to investigate whether PTEN promoter methylation contributes to PTEN inactivation in ameloblastoma and its associated protein expression. Material and Methods In total, 20 fresh-frozen ameloblastoma samples were evaluated for PTEN promoter methylation using methylation-specific polymerase chain reaction (MS-PCR). A subset of 10 paraffin-embedded ameloblastoma samples was examined for PTEN expression through immunohistochemistry. Four primary cultured ameloblastoma cells were investigated for PTEN promoter methylation and PTEN transcriptional expression via reverse transcription PCR. Results PTEN promoter methylation was detected in 65% (13/20) of the ameloblastoma samples. Of 10 ameloblastoma samples, 4 exhibited reduced PTEN expression. Of 5 samples with methylated PTEN, 3 (60%) were associated with loss of PTEN expression. However, PTEN expression was detected in 4 (80%) of 5 samples with unmethylated PTEN. In addition, 3 (75%) of 4 primary ameloblastoma cell cultures exhibited an inverse correlation between PTEN promoter methylation and PTEN transcription level. Conclusions PTEN promoter methylation is found in a number of ameloblastomas but not significantly correlated with loss of PTEN expression. Genetic or epigenetic mechanisms other than PTEN promoter methylation may contribute to PTEN inactivation in ameloblastoma tumor cells. Key words:PTEN, promoter methylation, ameloblastoma.

Three-dimensional radiographic features of ameloblastoma and cystic lesions in the maxilla.

To characterize the radiographic features of maxillary ameloblastoma (AM), odontogenic keratocyst (OKC) and dentigerous cyst (DC) comparatively by using spiral CT and cone beam CT (CBCT). Clinical records, histopathological reports, and nonenhanced spiral CT or CBCT images of 191 consecutive patients with primary maxillary AMs, OKCs, or DCs were retrospectively acquired, and radiographic features were analyzed. The study included 118 males and 73 females (age: 5-84 years). 72.0% of AMs and 84.3% of OKCs originated from the posterior maxilla, while 69.6% of DCs occurred in the anterior maxilla. Among 25 AMs, 44.0% were of desmoplastic type, with honey-combed appearance. 84.0% of AMs were circular or oval in shape, 84.0% expanded buccally, and 36.0% invade the nasal floor. Among 89 OKCs of 88 patients, 61.8% were circular or oval, 58.4% expanded buccally, 49.4% were dentigerous, 41.6% nearly filled the maxillary sinus, and 13.5% invaded the nasal floor. 93.7% (74/79) of DCs enveloped a single tooth, and the tooth-cyst relationship was centripetal in 35, eccentric in 30, and circumferential in 9. Moreover, 98.2% (55/56) of the cysts enveloping a supernumerary tooth were DCs, while 80.9% (38/47) of the cysts enveloping the third molar were OKCs. Maxillary AMs tend to grow with buccal expansion and invade the nasal floor, and DAs with honey-combed lobularity are common. Maxillary OKCs have variant shapes and tend to invaginate the maxillary sinus. The tooth-cyst relationship of dentigerous OKCs and DCs can be centripetal, eccentric, or circumferential.

Primary sinonasal ameloblastoma - a rare cause of unilateral nasal obstruction

Introduction. Ameloblastoma is a rare, locally invasive benign jaw tumour, originating from odontogenic epithelium, and their presence in the sinonasal tract is usually due to their spread from the gnathic region of the maxilla. Primary sinonasal ameloblastoma is extremely rare, with only a handful of reported cases so far. The objective of this article was to describe a patient with a primary ameloblastoma of the right maxillary sinus and nasal cavity. Case outline. We report a case of a 67-year-old male patient with a year-long history of progressive unilateral nasal obstruction. Clinical and computed tomography examination revealed a mass in the right maxillary sinus and right nasal cavity. After an in-office biopsy under local anesthesia, which suggested the diagnosis of ameloblastoma, the patient underwent complete removal of the mass by a medial partial maxillectomy. Histopathologic analysis confirmed the diagnosis of ameloblastoma. Conclusion. Primary sinonasal ameloblastoma is clinically and radiographically similar to the more common pathology of this particular area and should be included in the differential diagnosis of the unilateral nasal obstruction. The treatment of choice is complete surgical resection. Due to the rarity of the disease, and a small number of cases described so far in the literature, there is still no consensus regarding the optimal surgical technique.

Ameloblastoma: a retrospective single institute study of 34 subjects

Objective: This study aims to clarify demographic and clinical aspects of patients with ameloblastoma treated at a single Finnish institute during 1985–2016. Associations between predictor variables (gender and age) and outcome variables (location, tumour type, growth patterns and average tumour size) were sought.Materials and methods: A retrospective cohort study was designed and implemented including 34 patients diagnosed with primary ameloblastoma and treated at the Helsinki University Central Hospital. Patient records were investigated, and tissue samples re-evaluated. The chi-square test was used on all categorized variables and t-test for continuous ones. A p value equal to or under .05 was considered significant.Results: Males were slightly more predominant among the Finnish patients with ameloblastoma. Maxillary tumours were seen exclusively in male patients (p = .034). Additionally, these patients were older than patients with mandibular tumours (p = .007). A mixture in histological growth patterns was more common than originally anticipated. The study revealed a wide range of clinical signs and subjective symptoms, of which pain or other sensations were experienced most often.Conclusions: This study of 34 subjects shows that southern Finnish patients with ameloblastoma do not substantially differ from patients in similar study designs.

Imaging analysis of ameloblastoma, odontogenic keratocyst and dentigerous cyst in the maxilla using spiral CT and cone beam CT

Objective: To analyze the radiolographic features of ameloblastoma (AM), odontogenic keratocyst (OKC) and dentigerous cyst (DC) in the maxilla by spiral CT (SCT) and cone-beam CT (CBCT), and to provide useful information for the differential diagnosis of benign radiolucent lesions in the maxilla. Methods: Clinical records, histopathological reports and SCT or CBCT imaging of 85 patients with primary maxillary AM, OKC or DC admitted to Peking University School and Hospital of Stomatology from December 2012 to May 2017 were collected. Radiographic characteristics including site, size, shape, cortex expansion, internal structure and effects on neighboring tissue were analyzed. For OKC and DC, the relationship between cysts and enveloped teeth was classified as centripetal, eccentric and adherent. Results: The 85 patients included 56 males and 29 females, aged from 8 to 84 years old. Eighty-three patients had a single lesion, whereas 2 patients had bilateral cysts. In total, 87 lesions were analyzed, comprising 22 AM, 45 OKC and 20 DC. Among the 22 AM, 11 lesions were desmoplastic type, 16 were round-like in shape and 18 presented with buccal expansion. The shapes of the 45 OKC varied as round-like (n=26), oval (n=3), reniform (n=4), sinus-like (n=5), sinus+round (n=5) and irregular (n=2). Furthermore, 30 OKC presented with buccal expansion, 22 nearly filled the maxillary sinus and 26 were 'dentigerous'. The tooth-cyst relationship of the 'dentigerous' OKC was centripetal in 11, eccentric in 4 and adherent in 11. Among the 20 unicystic DC, 8 lesions were centripetal, 6 were eccentric and 6 were adherent type; 16 DC presented with buccal expansion. Conclusions: Demosplastic type is common in maxillary AM. Most AM are round-like in shape and expand buccally. The shape of maxillary OKC varies greatly and maxillary sinus filling is common. More than a half of OKC appear 'dentigerous'. For DC and OKC, tooth-cyst relationship can be centripetal, eccentric and adherent.

High frequency of BRAFV600E mutations in ameloblastoma

Ameloblastoma is a benign but locally infiltrative odontogenic neoplasm. Although ameloblastomas rarely metastasise, recurrences together with radical surgery often result in facial deformity and significant morbidity. Development of non-invasive therapies has been precluded by a lack of understanding of the molecular background of ameloblastoma pathogenesis. When addressing the role of ERBB receptors as potential new targets for ameloblastoma, we discovered significant EGFR over-expression in clinical samples using real-time RT–PCR, but observed variable sensitivity of novel primary ameloblastoma cells to EGFR-targeted drugs in vitro. In the quest for mutations downstream of EGFR that could explain this apparent discrepancy, Sanger sequencing revealed an oncogenic BRAF V600E mutation in the cell line resistant to EGFR inhibition. Further analysis of the clinical samples by Sanger sequencing and BRAF V600E-specific immunohistochemistry demonstrated a high frequency of BRAF V600E mutations (15 of 24 samples, 63%). These data provide novel insight into the poorly understood molecular pathogenesis of ameloblastoma and offer a rationale to test drugs targeting EGFR or mutant BRAF as novel therapies for ameloblastoma.

Epidemiology of ameloblastomas of the jaws; a report from the Netherlands.

Objectives: To provide epidemiological data of ameloblastomas of the jaws in the Netherlands over a 25-year time period (1985-2010) and to compare these data with data from other parts of the world. Material and Methods: The data of all patients diagnosed with a primary ameloblastoma of the jaws in the Netherlands in the period 1985-2010 have been retrieved from the nationwide histopathology and cytopathology network and registry in the Netherlands (PALGA). The pathology reports were screened and only those cases were included in which a distinct diagnosis of primary, histopathologically benign, intraosseous ameloblastoma was rendered. The average population in The Netherlands during this period amounted approximately 15 million people. Results: An annual incidence rate was approximately 1,5 per million population, the male-female ratio being 1.4: 1. The age at the time of diagnosis was 44.1 years. The average age in males was 46.3 years compared to an average age in females of 41.3 years, the difference being significant (p≤ 0.05). The results were compared with those available in only a small number of publications worldwide. Conclusions: There is no strong evidence for significant differences of the true incidence of ameloblastomas worldwide, neither for a gender predilection. The diagnosis is generally made at a somewhat lower age in women; this phenomenon is even much stronger in the Black population, irrespective of gender. No proper explanation for this finding can be provided. Key words:Odontogenic tumor, ameloblastoma, epidemiology.

The variability and complexity of ameloblastoma: Carcinoma ex ameloblastoma or primary ameloblastic carcinoma

Ameloblastoma is characterized by slow-growing, local invasiveness and high incidence of local recurrence. It usually presents with a benign histological appearance. However, ameloblastoma occasionally demonstrates a clinical course that is characteristic of malignant transformation. Here, we present a case of ameloblastoma with an aggressive clinical course, including multiple recurrences, a short disease-free interval, pulmonary metastasis and extensive skull-base infiltration. With a careful re-evaluation of the histology and cytology of the specimens of primary and recurrent ameloblastoma in 2006 and 2007, malignant transformation was observed and carcinoma ex ameloblastoma was ultimately diagnosed.

Malignant Ameloblastoma: Concurrent Presentation of Primary and Distant Disease and Review of the Literature

Malignant ameloblastoma is a rare tumor of odontogenic origin with a metastatic focus. Distant metastatic disease is found most commonly in the lungs. A review of the literature shows that most cases of malignant ameloblastoma involve a disease-free period from primary tumor extirpation to the discovery of metastasis. This report describes the case of a 56-year-old man presenting with ameloblastoma of the maxilla and a solitary pulmonary metastasis concurrently. This represents a rare case in which there is a simultaneous diagnosis of primary ameloblastoma and a metastatic lesion. Appropriate workup for ameloblastoma includes surveillance for metastatic disease. Surgical resection of primary and distant disease is recommended. Chemotherapy and radiation may play a role in palliation when resection of metastatic disease is not feasible.

Ameloblastoma of the Sinonasal Tract: Report of a Case with Clinicopathologic Considerations

Ameloblastomas are locally aggressive jaw tumours with a high propensity for recurrence and are believed to arise from remnants of dental lamina or odontogenic epithelium. Extragnathic ameloblastomas are unusual, and primary sinonasal tract origin is very uncommon with few cases reported in the literature. We herein report a case of primary sinonasal ameloblastoma presented in a 74-year-old male with nasal obstruction, rhinorrhoea, and sinusitis. Nasal endoscopy showed the right nasal cavity completely obstructed by a polypoid lesion attached to the lateral nasal wall. A preoperative CT scan was performed showing a solid lesion, measuring 2 cm in the maximum diameter, extending from the nasopharynx area with obstruction of the ostiomeatal unit and sphenoethmoidal recess into the lateral pharyngeal space, laterally to the parotid, without continuity with maxillary alveola and antrum. The tumour was completely excised endoscopically, and a final diagnosis of ameloblastoma was rendered. At the 12-month followup, there was no evidence of recurrence.