Ameloblastoma: current etiopathological concepts and management

THE MANAGEMENT OF TEETH IN ODONTOGENIC KERATOCYST AND AMELOBLASTOMA AND ITS PROGNOSTIC ROLE IN RECURRENCE: A SYSTEMATIC REVIEW AND META-ANALYSIS WITH TRIAL SEQUENTIAL ANALYSIS

INTRODUCTION

Odontogenic Keratocystic (OKC) and Ameloblastoma (AB) are pathological entities characterized by aggressive behavior, slow growth, local invasiveness, and high recurrence rates. The aim of this systematic review with meta-analysis and trial sequential analysis (TSA) is to assess the prognostic role of extracting involved teeth during the surgical enucleation of OKCs and ABs in terms of recurrence risk.

MATERIALS AND METHODS

A search was conducted in PubMed/Medline, Scopus, and Web of Science databases for studies reporting data on teeth extraction and recurrence rates. This systematic review was performed according to guidelines in the Cochrane Handbook and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. Meta-analysis was performed using the Mantel-Haenszel method with a random-effects model due to heterogeneity. The TSA was conducted to control and reduce for type I and II errors of statistical analysis.

RESULTS

Six studies were identified and analyzed qualitatively and quantitatively. A total of 737 lesions (674 OKCs and 64 ABs) were included, of which 508 had involved teeth. The meta-analysis included 451 OKCs; 367 lesions were treated with teeth extraction, and in 141 cases, the teeth were preserved. The overall Risk Ratio was 0.17 (95% CI: [0.04, 0.74]; P < .0001) for OKCs. Quantitative analysis could not be performed for ABs.

CONCLUSION

The analysis revealed that tooth extraction contextually to the enucleation of the lesion reduces the risk of recurrence by approximately 83% in the OKCs; this appears to have the same trend for ABs, but more evidence is needed.

Gross histopathological features and treatment outcomes of ameloblastoma at Khartoum teaching dental hospital: A retrospective cross-sectional study

AIM

The aim of this study is to interrogate the gross histopathological patterns, correlation between histological type with tumor location, treatment, and complications of patients with ameloblastomas seen at Khartoum Teaching Dental Hospital.

METHOD

This was a cross-sectional retrospective laboratory-based study using 390 patients identified histologically with ameloblastoma between the years 2010-2017. Information regarding age, gender, histopathologic type, anatomical site, tumour size, clinical and radiographic data as well as biological features of the types of ameloblastoma was obtained from laboratory demand outlines. Categorical and continuous variables were summarized in percentage and mean ± standard deviation, respectively. Continuous and categorical variables were summarized using mean ± standard deviation (SD) and percentages, respectively. Sociodemographic characteristics and healthcare-related variables were compared using the chi-square test, while economic status was analyzed using Duncan's multiple range test.

RESULTS

A total of 390 patients of ameloblastoma were included with a mean patient age of 30.74 ± 5.21 years (range: 9-68 years), male to female ratio of patients was 1.3:1. Maximum of approximately 68.46% (n = 267) patients presented with a painless swelling involving the mandible. Follicular pattern was the most predominant histopathological pattern 44.87% (n = 175) followed by plexiform pattern, accounted for 32.82% (n = 128) but in the recurrent cases, there was a relatively higher number of plexiform patterns 11.54% (n = 45), unlike other histopathological patterns. Patients that had recurrence, only 1.28% (n = 5) were treated by radical surgery compared to 23.32% (n = 91) who underwent conservative surgery.

CONCLUSION

This investigation reports a reasonably significant rate of recurrence in approximately a quarter 24.62% (n = 96) of the study patients. This is the largest histopathological study regarding ameloblastoma management from Sudan, and our results recommending radical surgery for the treatment of tumours.

Risk Factors and Nomogram for Predicting the Recurrence of Conventional Ameloblastoma

OBJECTIVE

To identify risk factors for the recurrence of conventional ameloblastoma (AM) and develop a predictive nomogram model for postoperative recurrence.

METHODS

Clinical, pathological, and radiographic data from 235 patients treated at the Hospital of Stomatology, Sun Yat-sen University (2005-2022) were retrospectively analyzed. Logistic regression identified independent prognostic factors, and a nomogram model was constructed using R software.

RESULTS

Multilocularity, cortical bone perforation, and inferior alveolar nerve involvement significantly increased recurrence risk in conventional AM (p < 0.05). Logistic regression analysis revealed that multilocular tumors (OR = 3.68, p = 0.002), honeycomb patterns (OR = 10.80, p < 0.001), and cortical bone perforation (OR = 2.62, p = 0.011) were significantly associated with increased recurrence risk. Surgical approaches significantly impacted recurrence rates, with curative resection surgery (CRS) resulting in the lowest recurrence risk as compared with fenestration decompression (FD) and local curettage (LC). CRS and curettage and fenestration decompression (CFD) were identified as effective protective factors against recurrence (p < 0.001). A nomogram model with high predictive accuracy (AUC = 0.867) was developed.

CONCLUSION

Multilocularity, cortical bone perforation, and inferior alveolar nerve involvement significantly increased the risk of recurrence. The nomogram model provided effective risk assessment for clinical decision-making.

Programmed death-ligand 1 regulates ameloblastoma growth and recurrence

Tumor cell-intrinsic programmed death-ligand 1 (PD-L1) signals mediate tumor initiation, progression and metastasis, but their effects in ameloblastoma (AM) have not been reported. In this comprehensive study, we observed marked upregulation of PD-L1 in AM tissues and revealed the robust correlation between elevated PD-L1 expression and increased tumor growth and recurrence rates. Notably, we found that PD-L1 overexpression markedly increased self-renewal capacity and promoted tumorigenic processes and invasion in hTERT+-AM cells, whereas genetic ablation of PD-L1 exerted opposing inhibitory effects. By performing high-resolution single-cell profiling and thorough immunohistochemical analyses in AM patients, we delineated the intricate cellular landscape and elucidated the mechanisms underlying the aggressive phenotype and unfavorable prognosis of these tumors. Our findings revealed that hTERT+-AM cells with upregulated PD-L1 expression exhibit increased proliferative potential and stem-like attributes and undergo partial epithelial‒mesenchymal transition. This phenotypic shift is induced by the activation of the PI3K-AKT-mTOR signaling axis; thus, this study revealed a crucial regulatory mechanism that fuels tumor growth and recurrence. Importantly, targeted inhibition of the PD-L1-PI3K-AKT-mTOR signaling axis significantly suppressed the growth of AM patient-derived tumor organoids, highlighting the potential of PD-L1 blockade as a promising therapeutic approach for AM.

Ameloblastoma Diagnosis From Serum Metabolic Profiling

INTRODUCTION

Ameloblastoma (ABM) is an aggressive, localized, infiltrating epithelial odontogenic neoplasm. The molecular pathogenesis of ABM is unknown, and studying its metabolic profile may allow the identification of biomarkers relevant to the diagnosis and prediction of pathology.

METHODS

Metabolomic analysis of 41 serum samples from 21 ABM patients and 20 healthy controls (HCs) was performed using gas chromatography-mass spectrometry (GC-MS). Using LASSO regression and receiver operating characteristic analysis, biomarker metabolites were screened and validated, and a diagnostic model was established. Tissue samples from ABM patients were analyzed using BRAF V600E-specific immunohistochemistry to investigate the impact of the BRAF V600E mutation on metabolic reprogramming in ABM.

RESULTS

A total of 73 metabolites were identified in the samples. The ABM had a total of 32 dysregulated metabolites, of which 30 were downregulated. A diagnostic panel of 10 metabolites was then generated. The panel accurately identified ABM with 100% sensitivity, 100% specificity, and an AUC of 1.00. In addition, the presence of the BRAF-V600E mutation in ABM is associated with increased serum glutamine levels.

CONCLUSION

This study identified distinct metabolic characteristics of ABM and established a diagnostic model. Our research also shows that BRAF-V600E may contribute to metabolic alterations in ABM.

Time to Recurrence of Ameloblastoma and Associated Factors in a Multi-institutional Black Patient Cohort

Ameloblastoma is a highly recurrent odontogenic neoplasm with variable global distribution. However, impact of race and ethnicity on ameloblastoma recurrence are still unclear. The primary aim of this study was to assess duration of time between primary and recurrent ameloblastomas in a predominantly Black multi-institutional patient cohort and secondarily to determine whether recurrent ameloblastomas are more readily discovered when clinically-symptomatic rather than by radiographic surveillance. A retrospective cross-sectional design was used to evaluate demographic, clinical, and pathological information on recurrent ameloblastomas patients. Outcome variable was time to recurrence, determined as period between the diagnosis of primary and recurrent ameloblastomas. We assessed associations between outcome variable and race, time lapse between primary and recurrent ameloblastomas and clinical symptoms of recurrent ameloblastomas at time of diagnosis. Among 115 recurrent ameloblastomas identified, 90.5% occurred in adults, 91.3% in Blacks, and similarly, 91.3% were conventional ameloblastomas. About 41% affected the posterior mandible. 93.9% were clinically symptomatic at time of presentation while 6.1% non-symptomatic lesions were discovered by routine diagnostic radiology. Median time to presentation of recurrent tumor was significantly longer in females (90 months, p = 0.016) and clinically symptomatic group of ameloblastoma patients (75 months, p = 0.023). Ameloblastoma recurrence was distinctively high in Black patients, occurred faster in males than females and was located mostly in the posterior mandible. Concomitant with delayed access to healthcare of Black individuals, routine post-surgical follow-up is essential because time lag between primary and recurrence tumors was longer in clinically symptomatic ameloblastomas at the time of diagnosis.

Plexiform ameloblastoma: a potential diagnostic challenge

OBJECTIVE

Ameloblastoma is a benign, locally aggressive neoplasm of the jaws. Accurate diagnosis is important for providing timely treatment and reducing the risk of recurrence and local destruction. The criteria for diagnosing ameloblastoma are well-defined, however, rare cases have been observed with a multicystic/unicystic plexiform pattern that lacks pathognomonic histologic features, causing difficulties in differentiating them from less aggressive jaw lesions. Our main objective was to review these plexiform ameloblastomas that could prove challenging for pathologists on incisional biopsies.

STUDY DESIGN

We reviewed cases of ameloblastoma in the University of Toronto diagnostic biopsy service from 2004 to 2024, n = 200. Cases with a microscopic description of cystic plexiform epithelial proliferation were retrieved for analysis of histopathologic features, clinical and radiographic information.

RESULTS

A rare subset of ameloblastoma (4%, 8 of 200) presented a distinctive histologic appearance of cystic plexiform proliferation lacking ameloblast-like cells, but clinical and radiographic features characteristic of ameloblastoma. Immunohistochemical staining for the BRAF p.V600E mutation was positive in 7 of 8 cases, demonstrating the importance of BRAF testing to aid in diagnosis.

CONCLUSIONS

Our study highlights an uncommon and potentially challenging histologic pattern of ameloblastoma for which a coordinated approach using clinical, radiographic, histologic, and molecular studies are needed for timely and accurate diagnosis.

Clinicopathological and Immunohistochemical Risk Predictors for Ameloblastoma Recurrence

PURPOSE

Measure associations between clinicopathological and immunohistochemical human Mut-L homologue 1 (hMLH1) gene, and human Mut-L homologue 2 (hMSH2) genes, variables in recurrent AMBs.

METHODS

This study consisted of a research retrospective, observational case-control study consisting of 22 cases of recurrent AMB and 22 non-recurrent cases. Cases of AMB with more than one year of follow-up were included in the study. Quantitative immunohistochemical analysis was performed considering the cellular location (nuclear) of the proteins studied. The McNemar test was used to compare variables between primary and recurrent AMBs. Recurrence-free survival was analyzed by the Kaplan-Meier method and survival functions were compared according to the variables using the log-rank test.

RESULTS

The posterior mandible was the most affected site in the recurrent (n = 18, 81.8%) and non-recurrent groups (n = 16, 72.8%). Recurrence-free survival was 50.0 (34.5-63.6) months. The following factors were significantly associated with AMB recurrence: presence of cortical bone expansion (p = 0.01), absence of bone reconstruction (p = 0.02), conservative treatment (p = 0.02), loss of hMSH2 (p = 0.01) and hMLH1 (p = 0.04) immunoexpression, and strong Ki-67 immunoexpression (p = 0.03). The risk factors for AMB recurrence were anatomical location (OR = 3.31), locularity (OR = 1.07), cortical expansion (OR = 6.17), cortical perforation (OR = 2.10), bone resorption (OR = 1.52), tooth impaction (OR = 1.86), jaw reconstruction (OR = 6.92), and immunoexpression of hMSH2 (OR = 10.0) and hMLH1 (OR = 4.50).

CONCLUSION

Radiographic appearance, treatment modality, and immunoexpression of mismatch repair proteins can be used as predictors of AMB recurrence.

Deciphering the secret codes in N7-methylguanosine modification: Context-dependent function of methyltransferase-like 1 in human diseases

N7-methylguanosine (m7G) is one of the most prevalent post-transcriptional modifications of RNA and plays a critical role in RNA translation and stability. As a pivotal m7G regulator, methyltransferase-like 1 (METTL1) is responsible for methyl group transfer during the progression of m7G modification and contributes to the structure and functional regulation of RNA. Accumulating evidence in recent years has revealed that METTL1 plays key roles in various diseases depending on its m7G RNA methyltransferase activity. Elevated levels of METTL1 are typically associated with disease development and adverse consequences. In contrast, METTL1 may act as a disease suppressor in several disorders. While the roles of m7G modifications in disease have been extensively reviewed, the critical functions of METTL1 in various types of disease and the potential targeting of METTL1 for disease treatment have not yet been highlighted. This review describes the various biological functions of METTL1, summarises recent advances in understanding its pathogenic and disease-suppressive functions and discusses the underlying molecular mechanisms. Given that METTL1 can promote or inhibit disease processes, the possibility of applying METTL1 inhibitors and agonists is further discussed, with the goal of providing novel insights for future disease diagnosis and potential intervention targets. KEY POINTS: METTL1-mediated m7G modification is crucial for various biological processes, including RNA stability, maturation and translation. METTL1 has emerged as a critical epigenetic modulator in human illnesses, with its dysregulated expression correlating with multiple diseases progression and presenting opportunities for both diagnostic biomarker development and molecular-targeted therapy. Enormous knowledge gaps persist regarding context-dependent regulatory networks of METTL1 and dynamic m7G modification patterns, necessitating mechanistic interrogation to bridge basic research with clinical translation in precision medicine.

Immunohistochemical Evaluation of p300, H2AacK5 and H3AcK27 in Odontogenic Cysts and Tumors

The acetylation of histones H2A on lysine 5 (H2AacK5) and H3 on lysine 27 (H3AcK27) modulate several cellular mechanisms through the p300 enzyme in pathological lesions; however, their role in odontogenic lesions has not been addressed. This study aims to evaluate the immunoexpression of p300, H2AacK5, and H3AcK27 in samples of ameloblastoma (AMB) (n = 30), odontogenic keratocyst (OK) (n = 15), adenomatoid odontogenic tumor (AOT) (n = 10), odontogenic fibroma (OF) (n = 8), calcifying odontogenic cyst (COC) (n = 8), odontogenic myxoma (MIX) (n = 10), and ameloblastic fibroma (AF) (n = 06). The percentage of p300-positive cells was higher in AOT and decreased in COC, OK, AMB, AF, OF, and MIX. H2AacK5-positive cells were higher in AF and decreased in AOT, COC, OK, OF, AMB, and MIX, whereas H3acK27-positive cells were higher in AOT and decreased in COC, OK, AF, OF, AMB, and MIX. The expression of these proteins was higher in nonaggressive lesions in comparison to aggressive lesions. There was a positive correlation between p300 and H2AacK5, and H3acK27 in AMB, MIX, and OF, whereas there was a positive correlation between p300 and H2AacK5 in AOT and COC. The histone acetylation may be involved in the biological behavior of these lesions, which could be used to improve their diagnosis and treatment.

Classification and prognostic evaluation of ameloblastoma using multiplanar CT imaging: a retrospective analysis

BACKGROUND

Ameloblastoma is the most prevalent odontogenic tumor of the jaw, with a significant recurrence rate. It was conventionally classified radiographically as unilocular or multilocular. As 3D images become more common, there is a need to reassess this classification. This study aimed to conduct a multi-planar assessment of ameloblastoma using CT images, reclassify the lesions based on locularity, and correlate the locularity with imaging characteristics and recurrence.

METHODS

Panoramic radiographs and CT images of histopathologically confirmed 255 ameloblastoma patients were included. The analysis encompassed imaging features including locularity, expansion, thinning, cortical perforation, and root resorption. Image characteristics associated with recurrence rate were examined, and image features were assessed based on locularity.

RESULTS

On panoramic radiographs, most ameloblastomas (68.6%) were classified as multilocular, while 31.4% were unilocular. The CT scan demonstrated that 46.3% of the ameloblastomas were pseudo-multilocular, 29.4% were unilocular, and 24.3% were multilocular. Multilocular cases on panoramic radiographs often appeared as pseudo-multilocular on CT. Cortical perforation, root resorption, and size were significantly correlated with CT locularity types (p < 0.05). The recurrence rate was 14.11%, and the risk of recurrence was substantially reduced by mandibulectomy and a larger tumor size. No other variables were significantly related to recurrence.

CONCLUSION

An accurate diagnosis of ameloblastoma and surgical planning to reduce the recurrence rate are contingent upon the use of three-dimensional imaging modalities, such as CT.

Unraveling the Mysteries of Ameloblastoma in African Population: A Comprehensive Analysis of 371 Cases from Clinical, Radiological, and Histopathological Perspectives

OBJECTIVE

To analyze the frequency, clinical, histopathological, and radiological characteristics of ameloblastoma in Nigeria over the course of two decades.

STUDY DESIGN

A retrospective analysis was conducted on 371 cases at a Nigerian university hospital between 2000 and 2023. Age, gender, site, histological variants, tumor size and duration were analyzed. Statistical analyses included the Shapiro-Wilk test, Mann-Whitney U test, Chi-square test, and Spearman rank correlation analysis.

RESULTS

The median patient age was 30 years (mean age 32.2), with a male-to-female ratio of 1.12:1. 54.7% of cases occurred in young adults (age range 20-39 years). Among the lesions, 11.3% were in the maxilla and 88.7% in the mandible. Patients with mandibular lesions had a median age of 29 years, while those with maxillary lesions had a statistically significantly higher median age of 37.5 years p-value = 0.001. Median tumor size was 36 cm2 for the mandible and 24 cm2 for the maxilla (significant p-value of 0.002). There was no correlation between tumor size, age, or gender. However, there was a significant correlation between tumor size and the duration of the condition.

CONCLUSION

The study concludes that ameloblastoma is more frequent among younger individuals in Nigeria and often presents with larger tumor sizes, emphasizing the need for early detection and intervention.

Exploring the Rarity: Clinical insights and histopathological diversity of hybrid desmoplastic-plexiform ameloblastoma

Ameloblastoma represents a rare and locally aggressive odontogenic neoplasm, notable for its histopathological diversity. Among its subtypes, the desmoplastic and plexiform variants are relatively rare, with the hybrid form, encompassing both architectural patterns, representing an even more exceptional entity. This article delineates the clinical, radiological, and histopathological profile of a 45-year-old male presenting with pain persisting over the past month in the right posterior maxillary region. Radiographic imaging displayed a mixed radiolucent-radiopaque lesion with poorly demarcated margins, indicative of an aggressive pathology. Histopathological examination revealed a hybrid ameloblastoma, juxtaposing desmoplastic zones with densely fibrotic stroma and classic plexiform sections with epithelial strands in a reticular configuration. This unique hybrid variant underscores the complexity of ameloblastomas and necessitates comprehensive histopathological assessment, as radiological interpretations may prove insufficient for accurate diagnosis. Such detailed analysis contributes to understanding the biological behavior of this rare form, underscoring the need for heightened clinical awareness and continued investigative focus.

Factors related to risk of recurrence and recurrence free survival in ameloblastoma of the Jaws: A single centre retrospective analysis

PURPOSE

Ameloblastoma is a benign tumor originating from odontogenic epithelium with a global incidence of about 0.5 cases per million persons per year. The overall recurrence rate of ameloblastomas range from 55% -90%. In this retrospective study we have analyzed the factors associated with recurrence and recurrence free survival in ameloblastoma of the jaws.

METHODS

Retrospective chart review of 10 years was done from records directory. All demographic data, data on diagnostic modalities, clinical presentations, radiology, management and histology were taken into consideration. Kaplan Meir estimator was used to evaluate recurrence rate and Cox regression analysis (univariate and multivariate) was used to evaluate the odds ratio to find out the possible factors influencing risk of recurrence and influence recurrence free survival. ROC curve (Receiver Operating Characteristic) was used to find out the optimal cut off point for size of the lesion in predicting recurrence. A p value of < 0.05 was considered statistically significant at 95% confidence interval.

RESULTS

A total of 75 patients had recurrence with a median follow up of 65 months. The overall 5 year RFS was 19.5%. Conventional ameloblastomas, cortical/ soft tissue invasion, conservative treatment and tumor size ≥ 4 cm were independent predictors of recurrence.

CONCLUSION

Aggressive treatment is preferred for conventional ameloblastomas ≥ 4 cm with cortical/ soft tissue invasion.

Image-based multi-omics analysis for oral science: Recent progress and perspectives

OBJECTIVES

The diagnosis and treatment of oral and dental diseases rely heavily on various types of medical imaging. Deep learning-mediated multi-omics analysis can extract more representative features than those identified through traditional diagnostic methods. This review aims to discuss the applications and recent advances in image-based multi-omics analysis in oral science and to highlight its potential to enhance traditional diagnostic approaches for oral diseases.

STUDY SELECTION, DATA, AND SOURCES

A systematic search was conducted in the PubMed, Web of Science, and Google Scholar databases, covering all available records. This search thoroughly examined and summarized advances in image-based multi-omics analysis in oral and maxillofacial medicine.

CONCLUSIONS

This review comprehensively summarizes recent advancements in image-based multi-omics analysis for oral science, including radiomics, pathomics, and photographic-based omics analysis. It also discusses the ongoing challenges and future perspectives that could provide new insights into exploiting the potential of image-based omics analysis in the field of oral science.

CLINICAL SIGNIFICANCE

This review article presents the state of image-based multi-omics analysis in stomatology, aiming to help oral clinicians recognize the utility of combining omics analyses with imaging during diagnosis and treatment, which can improve diagnostic accuracy, shorten times to diagnosis, save medical resources, and reduce disparity in professional knowledge among clinicians.

Network pharmacology and in vitro experiments reveal the potential therapeutic effects of Scrophularia ningpoensis Hemsl in the treatment of ameloblastoma

PURPOSE

This study aimed to explore active ingredients in Scrophularia ningpoensis Hemsl (SNH) with potential effects on ameloblastoma (AM) using network pharmacological approach, bioinformatic gene analysis and in vitro cell experiments.

METHODS

The active ingredients and their corresponding targets of SNH were identified from the Traditional Chinese Medicine Systems Pharmacology (TCMSP), as well as SwissTargetPrediction. Disease targets of AM were selected from GeneCards and DisGeNET databases. Differentially expressed genes (DEGs) of AM were identified, and Gene Ontology enrichment analysis were performed using the Gene Expression Omnibus (GEO) dataset GSE38494 through bioinformatic analysis. The STRING database platform was utilized to generate a protein-protein interaction network diagram, followed by hub gene analysis using Cytoscape software. AutoDock Vina software was used to perform molecular docking verification of the effects of the active ingredients on potential core targets. Additionally, in vitro experiments including quantitative reverse transcription polymerase chain reaction (RT-qPCR), EdU assay and CCK-8 cell proliferation assay were conducted using AM cell line AM-1 after SNH extract treatment.

RESULT

The study revealed that SNH contains eight active ingredients and a total of 388 drug targets, including 10 potential core targets in AM. Hub genes identified in the analysis were CCNA2, HRAS, PTGS2, PIK3CB, FGFR1, CASP3, MMP1, SLC2A1, MMP14, and MME. Molecular docking analysis demonstrated strong binding activity between key active ingredients (β-sitosterol, scropolioside A_qt, scropolioside D, scropolioside D_qt, and sugiol) and target genes (CASP3, FGFR1, HRAS, PTGS2, and SLC2A1). Gene Ontology enrichment analysis indicated that SNH exerts its effects on AM through pathways related to cellular response to abiotic stimulus, cellular response to hypoxia, and exopeptidase activity. Immunohistochemical analysis using tissue microarray showed higher expression of MMP14 and PTGS2 in AM compared to dentigerous cyst. Using AM-1 cell line, RT-qPCR results confirmed that SNH suppressed the expression of MMP14 and PTGS2 at mRNA level. Additionally, the EdUassay and CCK-8 assay indicated the inhibitory effect of SNH on the proliferation of AM-1 cells.

CONCLUSION

These findings showed that SNH could suppress expression of MMP14 and PTGS2 and restrain the proliferation of AM. Our study highlights the potential of SNH as a promising therapeutic candidate for AM, which may provide more options for clinical treatment.

Histone H3K9 Methylation Is Differentially Modified in Odontogenic Cyst and Tumors

OBJECTIVES

 Histone modification in odontogenic lesions is mostly unexplored. Trimethylation of histone H3 at lysine residue 9 (H3K9Me3) has been studied in various pathologic conditions and showed biological significance promising for future therapeutic application. This study aimed to investigate the level and clinical relevance of the H3K9Me3 histone modification in odontogenic cysts and tumors.

MATERIALS AND METHODS

 A total of 105 cases of odontogenic lesions, comprising 30 odontogenic keratocysts (OKCs), 30 adenomatoid odontogenic tumors (AOTs), 30 ameloblastomas, and 15 dental follicles, were included in the study. The paraffin-embedded tissues were immunohistochemically stained for H3K9Me3. Both the intensity and the distribution of staining were evaluated and calculated as H-score. The correlation between the H3K9Me3 expression and the clinical characteristics of each lesion was evaluated.

STATISTICAL ANALYSIS

 The Kruskal-Wallis test followed by Bonferroni's correction was performed to assess the differences in H-score among groups. In addition, Pearson's chi-squared test or Mann-Whitney U test was used to analyze potential factors that could affect protein expression.

RESULTS

 The reduced enamel epithelium of the dental follicle showed uniformly strong H3K9Me3 expression. All odontogenic cysts and tumors examined demonstrated a significantly reduced H3K9Me3 level compared with dental follicles. The AOT showed the lowest H3K9Me3 level, followed by OKC and ameloblastoma. Its immunoreactivity was mainly localized in the basal and parabasal cells of OKC and the whorled/duct-like structures of AOT. Ameloblastoma exhibited marked variation in the H3K9Me3 level among cases. Notably, the upregulated H3K9Me3 was related to multilocularity of OKC and ameloblastoma.

CONCLUSIONS

 Histone H3K9 methylation is differentially expressed in odontogenic cysts and tumors. This epigenetic modification may contribute to the pathogenesis and aggressive behavior of odontogenic lesions.

Surgical management of conventional ameloblastoma: a retrospective cohort study over the past 21 years

Conventional ameloblastoma presents infiltrative behavior and its treatment ranges from enucleation combined with adjuvant therapies to marginal/segmental resection. The purpose of this study is to present a cohort of twenty-four patients with ameloblastoma treated in the same institution after marginal/segmental resection for the past 21 years. All cases had diagnosis confirmation by incisional biopsy. Patients with an unconfirmed diagnosis and missing follow-up information were excluded. Data were categorized into clinicopathological, surgical and recurrence aspects. Thirteen patients were females (54%). The mean age was 40.2 years. Mandible was the most affected site (91%). The mean length of the lesions was 4.10 cm (± 2.06) and the multilocular aspect was predominant (83%). Root resorption (37.5%), tooth displacement (45.8%) and cortical perforation (45.8%) were noticed. Histologically, most of the cases were follicular (n = 19,79%). Microscopic analysis showed positive margins in four cases. Patients were treated by marginal (n = 19) and segmental (n = 5) resections. Recurrence occurred in two cases (8.33%). Both primary and recurrent ameloblastomas were treated through marginal resections and no recurrence was observed during the past 9 and 5 years after the last intervention, respectively. The overall mean follow-up was 79.25 months and patients are still monitored over these years. Marginal/segmental resection of conventional ameloblastoma is associated with a low recurrence rate.

Decompression, an Unusual Treatment Option for Multicystic Ameloblastoma: Concepts and Controversies

Background: The most common odontogenic tumor is the solid ameloblastoma. This is concerning due to the progressive bone destruction in its intraosseous variant; this type of pathology often gets a delayed diagnosis due to the asymptomatic characteristic it has. Objective: The aim of the article is to propose a conservative treatment for multicystic ameloblastoma, reviewing the latest concepts, controversies, and treatment options described in the literature. Case Report: A patient arrives to our department with a diagnosis of unicystic ameloblastoma, so decompression and subsequent enucleation were decided as treatment. However, the new histopathological result was a multicystic ameloblastoma; with this result, we decided to continue with the initial treatment, which in fact had an adequate response. A 5-month radiographic follow-up was performed in which a decrease in size was evident and enucleation was decided. The postoperative results were favorable after a 2.5-year follow-up. Conclusion: The solid ameloblastoma may have a cystic component, in which there is the possibility of diagnostic errors when studying an incisional biopsy; for this reason, the definitive diagnosis should be established until complete enucleation of the lesion is performed. This characteristic in a solid ameloblastoma makes possible a positive response to decompression, making it easier to perform the enucleation subsequently, avoiding other aggressive treatments that can dramatically affect the patient's quality of life and also avoiding costly reconstruction bills.

The 'D-M-C' strategy for conventional ameloblastoma of the mandible: a retrospective study

The purpose of this multicentre study was to evaluate the efficacy of the 'dredging-marsupialization-curettage' (D-M-C) strategy in the treatment of conventional intraosseous ameloblastoma of the mandible. A total of 31 patients from three institutions, who had a pathological diagnosis of conventional ameloblastoma of the mandible, were treated with the D-M-C strategy. The surgical protocol comprised a dredging and marsupialization (D-M) step, with additional D-M steps as required. The patients then underwent curettage (C) once an obvious effect of the D-M step had been achieved during follow-up. Eight patients were followed up for ≥36 months but <60 months, while 23 were followed up for ≥60 months. Nineteen of the 23 patients followed up for ≥60 months were disease-free at the last follow-up, with no evidence of recurrence. The D-M step is effective for reducing the tumour size and preserving vital structures. The D-M-C surgical strategy may be a feasible treatment option for conventional ameloblastoma of the mandible.

BRAF V600E mutation mediates invasive and growth features in ameloblastoma

OBJECTIVES

Ameloblastoma (AM), a locally aggressive tumor with extensive growth capacity, causes significant damage to the jaw and affects facial appearance. Although the high prevalence of BRAF V600E mutation in AM is known, its specific impacts on patients with AM remain unclear. Thus, the present study investigated the role of BRAF V600E mutation, thereby focusing on its impact on AM invasion and growth.

MATERIALS AND METHODS

Immunohistochemical analysis was used to compare BRAF V600E, MMP2, MMP9, and Ki-67 expressions in AM (n = 49), normal oral mucosa (NOM) (n = 10), and odontogenic keratocyst (OKC) (n = 15) tissues. AM was further classified according to the presence or absence of BRAF V600E. The relationship between BRAF V600E and invasion as well as growth was evaluated. In addition, correlation analysis was performed using immunohistochemistry and confirmed via double-labeling immunofluorescence. Finally, comparative analyses using mass spectrometry, immunohistochemistry, and immunofluorescence were performed to explore and identify underlying mechanisms.

RESULTS

AM exhibited a higher incidence of BRAF V600E mutation than NOM and OKC. BRAF V600E expression was positively correlated with the invasion-associated proteins MMP2 and MMP9 and the growth-related protein Ki-67. Proteomic data revealed that BRAF V600E primarily activates the MAPK signaling pathway in AM, particularly driving the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2).

CONCLUSIONS

In summary, the findings suggested that the BRAF V600E mutation enhances the invasion and growth abilities of AM via the MAPK/ERK signaling pathway. Thus, targeting BRAF V600E or the MAPK/ERK pathway may be a potential AM therapy.

Differentially expressed extracellular matrix genes functionally separate ameloblastoma from odontogenic keratocyst

BACKGROUND

Ameloblastoma and odontogenic keratocyst (OKC) are odontogenic tumors that develop from remnants of odontogenic epithelium. Both display locally invasive growth characteristics and high predilection for recurrence after surgical removal. Most ameloblastomas harbor BRAFV600E mutation while OKCs are associated with PATCH1 gene mutation but distinctive indicators of ameloblastoma growth characteristics relative to OKC are still unclear. The aim of this study was to assess hub genes that underlie ameloblastoma growth characteristics using bioinformatic analysis, ameloblastoma samples and mouse xenografts of human epithelial-derived ameloblastoma cells.

METHODS

RNA expression profiles were extracted from GSE186489 gene expression dataset acquired from Gene Expression Ominibus (GEO) database. Galaxy and iDEP online analysis tools were used to identify differentially expressed genes that were further characterized by gene ontology (GO) and pathway analysis using ShineyGO. The protein-protein interaction (PPI) network was constructed for significantly upregulated differentially expressed genes using online database STRING. The PPI network visualization was performed using Cytoscape and hub gene identification with cytoHubba. Top ten nodes were selected using maximum neighborhood component, degree and closeness algorithms and analysis of overlap was performed to confirm the hub genes. Epithelial-derived ameloblastoma cells from conventional ameloblastoma were transplanted into immunocompromised mice to recreate ameloblastoma in vivo based on the mouse xenograft model. The top 3 hub genes FN1, COL I and IGF-1 were validated by immunostaining and quantitative analysis of staining intensities to ameloblastoma, OKC samples and mouse ameloblastoma xenografts tissues.

RESULTS

Seven hub genes were identified among which FN1, COL1A1/COL1A2 and IGF-1 are associated with extracellular matrix organization, collagen binding, cell adhesion and cell surface interaction. These were further validated by positive immunoreactivity within the stroma of ameloblastoma samples but both ameloblastoma xenograft and OKC displayed only FN1 and IGF-1 immunoreactivity while COL 1 was unreactive. The expression levels of both FN1 and IGF-1 were much lower in OKC relative to ameloblastoma.

CONCLUSION

This study further validates a differentially upregulated expression of matrix proteins FN1, COL I and IGF-1 in ameloblastoma relative to OKC. It suggests that differential stromal architecture and growth characteristics of ameloblastoma relative to OKC could be an interplay of differentially upregulated genes in ameloblastoma.

The Effect of Conservative vs. Radical Treatment of Ameloblastoma on Recurrence Rate and Quality of Life: An Umbrella Review

Ameloblastoma is a rare, benign, but locally aggressive odontogenic tumor that originates from the epithelial cells involved in tooth development. The surgical approach to treating an ameloblastoma depends on the type, size, location, and extent of the tumor, as well as the patient's age and overall health. This umbrella review's aim is to summarize the findings from systematic reviews (SRs) and meta-analyses on the effect of radical or conservative treatment of ameloblastoma on the recurrence rate and quality of life, to evaluate the methodological quality of the included SRs and discuss the clinical management. Three electronic databases (PubMed, Scopus, The Cochrane Library) were checked. The primary outcome was the recurrence rate after surgical treatment, while the secondary outcomes were the post-operative complications, quality of life, esthetic, and functional impairment. The methodological quality of the included SRs was assessed using the updated version of "A Measurement Tool to Assess Systematic Review" (AMSTAR-2). Eighteen SRs were included. The quality of the included reviews ranged from critically low (three studies) to high (eight studies). Four studies were included in meta-analysis, and they revealed that the recurrence rate is about three-times more likely in the conservative treatment group compared to the radical treatment group, and this result is statistically significant. Despite the high recurrence rate, the latter was more appropriate in the case of smaller lesions and younger patients, due to better post-operative quality of life and reduced functional and esthetic impairments. Based on the results of this overview, conservative treatment may be recommended as the first-line approach for intraosseous ameloblastoma not involving soft tissue. However, given the expectation of a higher recurrence rate, it is advisable to reduce the interval between follow-up visits. However, further prospective studies are needed to establish the best treatment choice and follow-up period.

Treatment of benign maxillomandibular osteolytic lesions larger than 4 cm: A systematic review

OBJECTIVE

This systematic review aimed to assess the different treatments of benign maxillo-mandibular radiolucent bone lesions over 4 cm to propose a management algorithm.

STUDY DESIGN

A literature search was conducted using MEDLINE/PubMed, Scopus, Google Scholar, Virtual Health Library databases, and gray literature. Randomized or non-randomized clinical trials and case series with 10 or more patients with a minimum follow up of 1 year, published in French or English until August 2023, were included. The risk of bias was assessed for all papers included.

RESULTS

Of 1433 records identified, 22 were included in this review, reporting data from 1364 lesions. Ameloblastoma was the most common lesion (51.22%) and mandible was the most common site (81.21%). Initial conservative treatment was prevalent (71.04%). Recurrence was higher after conservative (13.8%) than after radical treatments (6.5%). Multilocularity, cortical perforation, dental element preservation were linked to a higher recurrence risk.

CONCLUSION

This study has shown importance of understanding specific characteristics and recurrence risk in benign maxillomandibular osteolytic lesions. Multidisciplinary team approval, personalized approach based on lesion type and patient are crucial. The presence of at least one risk factor could lead to therapeutic decision. Despite limitations, the study informed lesion management and provided precise recommendations.

Diagnostic capability of artificial intelligence tools for detecting and classifying odontogenic cysts and tumors: a systematic review and meta-analysis

OBJECTIVE

To evaluate the diagnostic capability of artificial intelligence (AI) for detecting and classifying odontogenic cysts and tumors, with special emphasis on odontogenic keratocyst (OKC) and ameloblastoma.

STUDY DESIGN

Nine electronic databases and the gray literature were examined. Human-based studies using AI algorithms to detect or classify odontogenic cysts and tumors by using panoramic radiographs or CBCT were included. Diagnostic tests were evaluated, and a meta-analysis was performed for classifying OKCs and ameloblastomas. Heterogeneity, risk of bias, and certainty of evidence were evaluated.

RESULTS

Twelve studies concluded that AI is a promising tool for the detection and/or classification of lesions, producing high diagnostic test values. Three articles assessed the sensitivity of convolutional neural networks in classifying similar lesions using panoramic radiographs, specifically OKC and ameloblastoma. The accuracy was 0.893 (95% CI 0.832-0.954). AI applied to cone beam computed tomography produced superior accuracy based on only 4 studies. The results revealed heterogeneity in the models used, variations in imaging examinations, and discrepancies in the presentation of metrics.

CONCLUSION

AI tools exhibited a relatively high level of accuracy in detecting and classifying OKC and ameloblastoma. Panoramic radiography appears to be an accurate method for AI-based classification of these lesions, albeit with a low level of certainty. The accuracy of CBCT model data appears to be high and promising, although with limited available data.

Podoplanin immunoexpression in odontogenic lesions: a systematic review, meta-analysis, and integrated bioinformatic analysis

BACKGROUND

Podoplanin (PDPN) is a transmembrane glycoprotein implicated in the pathogenesis of odontogenic lesions (OL). It is localized at the membrane and cytoplasmic level, and its interaction with other proteins could trigger cell proliferation, invasion and migration. The main objective of this systematic review is to explore the immunoexpression pattern of podoplanin in OL. In addition, as secondary objectives, we aimed to compare the immunostaining intensity of PDPN in OL, to analyze its interaction networks by bioinformatic analysis and to highlight its importance as a potential diagnostic marker useful in the pathogenesis of OL.

METHODS

The protocol was developed following PRISMA and Cochrane guidelines. The digital search was performed in the databases: PubMed/MEDLINE, ScienceDirect, Scopus, Web of Science and Google Schoolar from August 15, 2010 to June 15, 2023. We included cross-sectional and cohort studies that will analyze the pattern of PDPN immunoexpression in OL. Two investigators independently searched for eligible articles, selected titles and abstracts, analyzed full text, conducted data collection, and performed assessment of study quality and risk of bias. In addition, part of the results were summarized through a random-effects meta-analysis. STRING database was used for protein-protein interaction analysis.

RESULTS

Twenty-nine relevant studies were included. The ages of the subjects ranged from 2 to 89 years, with a mean age of 33.41 years. Twenty-two point two percent were female, 21.4% were male, and in 56.4% the gender of the participants was not specified. A total of 1,337 OL samples were analyzed for PDPN immunoexpression pattern. Ninety-four (7.03%) were dental follicles and germs, 715 (53.47%) were odontogenic cysts, and 528 (39.49%) were odontogenic tumors. Meta-analysis indicated that the immunostaining intensity was significantly stronger in odontogenic keratocysts compared to dentigerous cysts (SMD=3.3(CI=1.85-4.82, p=0.000*). Furthermore, bioinformatic analysis revealed that PECAM-1, TNFRF10B, MSN, EZR and RDX interact directly with PDPN and their expression in OL was demonstrated.

CONCLUSIONS

The results of the present systematic review support the unique immunoexpression of PDPN as a potential useful diagnostic marker in the pathogenesis of OL.

Factors Associated with Recurrence of Ameloblastoma: A Scoping Review

PURPOSE

This scoping review aimed to identify factors associated with the recurrence of ameloblastoma.

METHODS

Systematic searches were conducted in PubMed, Scopus, and EMBASE, based on the board research question: "What factors are related to the recurrence of ameloblastoma?". English-language observational studies addressing the risk and preventive factors associated with recurrent ameloblastoma were included and data were extracted.

RESULTS

Eighty-three retrospective observational studies met the inclusion criteria. The identified prognostic factors for recurrence included: (1) Tumor size/diameter/volume, (2) cortical bone perforation/ soft tissue invasion, (3) multilocular radiolucency, (4) impacted tooth-involving lesions, (5) root resorption, (6) WHO classification - conventional (solid/multicystic) ameloblastoma, (7) histological subtype - mural invasion of unicystic ameloblastoma, (8) conservative treatment modalities - simple enucleation, curettage, and marsupialization, and (9) non-extraction/preservation of involved teeth. No strong evidence linked immunohistochemical expression to recurrence. Interestingly, BRAF p.V600E remained controversial in terms of recurrence, despite being a frequent finding in ameloblastoma.

CONCLUSION

Certain clinical characteristics, radiographic findings, histological subtypes, and treatment choices of ameloblastoma can help identify patients at high risk of recurrence. Further prospective studies to evaluate the prognostic factor model and research on immunohistochemistry are required.

Surgical management of mandibular ameloblastoma and immediate reconstruction with iliac crest and costochondrial bone grafts: A case report

INTRODUCTION AND IMPORTANCE

Ameloblastoma is a benign but locally aggressive odontogenic tumor mostly occurring in the jaws. Ameloblastoma can be difficult to diagnose because it mimics other benign lesions. Its diagnosis requires a combination of imaging data, histopathological analysis, and molecular tests. Its treatment modality diverges from simple enucleation with bone curettage up to wide surgical resections.

CASE PRESENTATION

A 25-year-old female presented with a right-sided mandibular mass for five years. Histopathology and radiology tests confirmed it to be an ameloblastoma. A hemimandibulectomy was done, followed by immediate reconstruction using an autogenously inserted iliac crest bone and a costochondral graft as an interposition graft for the lost part. The patient had a satisfactory clinical outcome, and no sign of recurrence after a follow-up of six months.

CLINICAL DISCUSSION

The ideal management of ameloblastoma should minimize recurrence, restore function and appearance, and present minimal donor site morbidity. While the removal of a wide part of the bone and soft tissue leads to defects that may cause functional and aesthetic concerns, conservative management is associated with minimal downtime but high recurrence rates. Reconstructive surgery is of paramount importance for the recovery of the lost parts in these patients.

CONCLUSION

Radical surgery is the treatment of choice for large tumors to minimize recurrence, and immediate reconstruction utilizing grafting techniques is essential to restoring function and appearance. The autologous bone graft technique is satisfactory for immediate mandibular reconstruction as it represents a simple, easy, less costly, and reliable method for restoring mandibular continuity defects.

Low Detection of High-risk Human Papilloma Virus in Individuals with Ameloblastoma in a Tertiary Hospital in Lagos, Nigeria

BACKGROUND

Ameloblastoma is a benign but aggressive epithelial odontogenic neoplasm of unknown etiology. The role of human papilloma virus (HPV) in the etiology of oral squamous cell carcinoma has prompted the investigation of HPV as an etiologic factor in ameloblastoma. This study aimed to determine the frequency of high-risk (HR) HPV in conventional ameloblastoma and the clinical parameters associated with infection.

MATERIALS AND METHODS

The study was approved by the ethical review boards of the institution. DNA was extracted from fresh tissue collected 750 μL of DNA/RNA Shield (Zymo Research, United States) using Invitrogen PureLink Viral RNA/DNA Mini Kit (Invitrogen, USA). The extracted DNA was assayed for the detection of 14 HR HPV types (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68) using Anyplex™ II HPV HR Detection kit (Cat. No. HP7E00X) (Seegene Inc., Republic of Korea) on CFX-96TM Real-Time Polymerase Chain Reaction (PCR) System (Bio-Rad). Data on gender, age of patient, site of lesion, clinicohistological types of ameloblastoma and history of smoking, alcohol consumption, and practice of oral sex were collected. Data analysis was performed using analysis program SPSS version 25 and statistical significance was set at P < 0.05.

RESULTS

Two cases of conventional ameloblastoma were positive with HPV and none of the ameloblastic carcinoma cases were positive. The HPV 16 serotype was observed in both cases. While 5 of the cases had a history of alcohol consumption, none of these cases were positive for HPV serotype.

CONCLUSIONS

HPV 16 positivity was detected in two cases of conventional ameloblastomas and none in ameloblastic carcinoma using real-time PCR. There was no effect of exposure to smoking, alcohol consumption, and practice of oral sex and HPV in the etiology of ameloblastoma. Data available are suggestive of a limited role of HPV in the etiology of ameloblastoma.

Targeting BRD4 attenuates the stemness and aggressiveness of ameloblastoma

BACKGROUND

BRD4, belonging to the bromodomain extra-terminal (BET) protein family, plays a unique role in tumor progression. However, the potential impact of BRD4 in ameloblastoma (AM) remains largely unknown. Herein, we aimed to assess the expression and functional role of BRD4 in AM.

METHODS

The expression level of BRD4 was assessed by immunohistochemistry. The proliferation, migration, invasion, and tumorigenic abilities of AM cells were assessed by a series of assays. To explore the molecular expression profile of BRD4-depleted AM cells, RNA sequencing (RNA-seq) was performed. Bioinformatic analysis was performed on AM expression matrices obtained from the Gene Expression Omnibus (GEO). The therapeutic efficacy of BET-inhibitors (BETi) was assessed with AM patient-derived organoids.

RESULTS

Upregulation of BRD4 was observed in conventional AMs, recurrent AMs, and ameloblastic carcinomas. Depletion of BRD4 inhibited proliferation, invasion, migration, and tumorigenesis in AM. Administration of BETi attenuated the aggressiveness of AM and the growth of AM patient-derived organoids. Bioinformatic analysis indicated that BRD4 may promote AM progression by regulating the Wnt pathway and stemness-associated pathways.

CONCLUSION

BRD4 increases the aggressiveness and promotes the recurrence of ameloblastoma by regulating the Wnt pathway and stemness-associated pathways. These findings highlight BRD4 as a promising therapeutic target in AM management.

Clinicopathological characteristics and diagnostic accuracy of BRAF mutations in ameloblastoma: A Bayesian network analysis

OBJECTIVE

This Bayesian network meta-analysis was performed to analyze the associations between clinicopathological characteristics and BRAF mutations in ameloblastoma (AM) patients and to evaluate the diagnostic accuracy.

MATERIALS AND METHODS

Four electronic databases were searched from 2010 to 2024. The search terms used were specific to BRAF and AM. Observational studies or randomized controlled trials were considered eligible. The incidence of BRAF mutation and corresponding clinicopathological features in AM patients were subjected to Bayesian network analyses and diagnostic accuracy evaluation.

RESULTS

A total of 937 AM patients from 20 studies were included. The pooled prevalence of BRAF mutations in AM patients was 72%. According to the Bayesian network analysis, BRAF mutations are more likely to occur in younger (odds ratio [OR], 2.3; credible interval [CrI]: 1.2-4.5), mandible site (OR, 3.6; 95% CrI: 2.7-5.2), and unicystic (OR, 1.6; 95% CrI: 1.1-2.4) AM patients. Similarly, higher diagnostic accuracy was found in the younger, mandible, and unicystic AM groups.

CONCLUSIONS

The incidence, risk, and diagnostic accuracy of BRAF mutation in AM were greater in younger patients, those with mandible involvement, and those with unicystic AM than in patients with other clinicopathological features. In addition, there was a strong concordance in the diagnostic accuracy between molecular tests and immunohistochemical analysis.

[Molecular basis of ameloblastoma pathogenesis: A review]

Ameloblastoma is the most common and highly invasive benign odontogenic tumor. Its pathogenesis is not yet fully understood.

Objective

To describe the most important molecular findings that promote the proliferative activity of ameloblastoma and the factors involved that encourage invasion into surrounding bone tissues.

Methodology

A search for scientific evidence was conducted through the following databases: Science Direct, Medline, Wiley, Web of Science, and Google Scholar. A total of 32 articles were reviewed, with inclusion criteria being articles published in English and Spanish; descriptive and analytical studies, narrative and systematic reviews published from January 2015 to June 2021. Letters to the editor were excluded.

Results

The biological molecular findings that allow ameloblastoma to invade surrounding tissues involve alterations in the RANK/RANKL/OPG pathways, transforming growth factor beta (TGF-β), Wnt/β-catenin pathway, and matrix metalloproteinases, as well as alterations in MAPK and SHH pathways that facilitate the proliferation and tumor development of ameloblastoma.

Conclusions

These findings are fundamental for a better understanding of the pathways involved in the pathogenesis of ameloblastoma.

Expression of Fascin and SALL4 in odontogenic cysts and tumors: an immunohistochemical appraisal

Background

Various stemness markers (SOX2, OCT4, and NANOG) have been studied in odontogenic cysts and tumors. However, studies on SALL4 having similar properties of stemness has not been documented. Additionally, insight into fascin as a migratory molecule is less explored. In this study, the expression of SALL4 and fascin were evaluated in ameloblastoma, adenomatoid odontogenic tumor (AOT), odontogenic keratocyst (OKC), dentigerous cyst (DC), radicular cyst (RC), and calcifying odontogenic cyst (COC).

Methods

Semi-quantitative analysis of fascin and SALL4 immuno-positive cells was done in a total of 40 cases of ameloblastoma (11 plexiform, 12 follicular, 12 unicystic, and 5 desmoplastic) variants, 6 cases of AOT, 15 each of OKC, DC, RC and 5 of COC. Chi-square test was applied to evaluate the association between SALL4 and fascin expression in odontogenic cysts and tumors.

Results

Fascin immunopositivity was observed in peripheral ameloblast-like cells, and the expression was weak or absent in stellate reticulum-like cells. A moderate to weak immune-reactivity to SALL4 was observed in the cytoplasm of ameloblastoma, epithelial cells of dentigerous and radicular cysts, having a marked inflammatory infiltrate, which was an interesting observation. COC and AOT had negative to weak expressions. No recurrence has been reported.

Conclusions

Expression of fascin in ameloblastomas elucidate their role in motility and localized invasion. Its expression in less aggressive lesions like DC, COC, AOT will incite to explore the other functional properties of fascin. SALL4 expression in the cytoplasm of odontogenic cysts and tumors may represent inactive or mutant forms which requires further validation.

Anti-MAPK Targeted Therapy for Ameloblastoma: Case Report with a Systematic Review

Ameloblastoma, a benign yet aggressive odontogenic tumor known for its recurrence and the severe morbidity from radical surgeries, may benefit from advancements in targeted therapy. We present a case of a 15-year-old girl with ameloblastoma successfully treated with targeted therapy and review the literature with this question: Is anti-MAPK targeted therapy safe and effective for treating ameloblastoma? This systematic review was registered in PROSPERO, adhered to PRISMA guidelines, and searched multiple databases up to December 2023, identifying 13 relevant studies out of 647 records, covering 23 patients treated with MAPK inhibitor therapies. The results were promising as nearly all patients showed a positive treatment response, with four achieving complete radiological remission and others showing substantial reductions in primary, recurrent, and metastatic ameloblastoma sizes. Side effects were mostly mild to moderate. This study presents anti-MAPK therapy as a significant shift from invasive surgical treatments, potentially enhancing life quality and clinical outcomes by offering a less invasive yet effective treatment alternative. This approach could signify a breakthrough in managing this challenging tumor, emphasizing the need for further research into molecular-targeted therapies.

Ameloblastoma With the Hybrid Desmoplastic and Plexiform Pattern: A Case Report

Ameloblastoma is an epithelial odontogenic tumor with a benign nature and demonstrates local aggressiveness. It frequently occurs between the third and fifth decades of life, showing significant gender predilection. While typically displaying a benign growth pattern, it tends to invade and sporadically metastasize locally. Ameloblastoma is predominantly found in the posterior regions. Periodic recur commonly follows insufficient treatment. Hence, conducting thorough identification of tumors and management is crucial to prevent relapse. Complications and improved prognosis are associated with meticulous surgical techniques, regular follow-up care, and early detection of recurrence. This study presented a report of a 19-year-old male with swelling in the left lower jaw, detailing its area of complaint, radiographic findings, histopathologic characteristics, and different treatment approaches. The uniqueness of the case is the hybrid histopathology of ameloblastoma composed of plexiform and desmoplastic variants.

Differential Expression of Immunohistochemical Markers in Ameloblastoma & Ameloblastic Carcinoma: A Systematic Review and Meta-analysis of observational studies

BACKGROUND

Differentiating between ameloblastoma (AB) and ameloblastic carcinoma (AC) is difficult, especially when AB has atypical cytological characteristics or an uncommon clinical history. This systematic review and meta-analysis aimed to elucidate the differential expression of immunohistochemical markers between AB and AC.

METHODS

We conducted a thorough search of PUBMED and SCOPUS according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify cross-sectional studies that compared the expression of immunohistochemical markers in AB and AC. We used a random-effects model to analyze the risk ratios and their corresponding 95% confidence intervals (CIs). The quality of the included studies was assessed using the Newcastle-Ottawa scale. The Egger's test was used to assess publication bias.

RESULTS

In total, 301 articles were identified. After excluding irrelevant titles and abstracts, 86 articles were selected for full-text review. We categorized the 41 markers into proliferative and non-proliferative markers. Among non-proliferative markers, nuclear markers were differentially expressed in AB and AC. SOX2 was the only marker that significantly differentiated AB and AC, with an RR of -0.19 (CI 0.10-0.36, I2=0).

CONCLUSION

The current evidence suggests the significance of SOX2 in differentiating between AB and AC, warranting prospective confirmation in well-defined extensive studies. We highlight the paucity of high-quality replicated studies of other markers in this field. Collaborative efforts with standardized techniques are necessary to generate clinically useful immunohistochemical markers.

Identification of Molecular Mechanisms of Ameloblastoma and Drug Repositioning by Integration of Bioinformatics Analysis and Molecular Docking Simulation

Background

Ameloblastoma (AM) is a benign tumor locally originated from odontogenic epithelium that is commonly found in the jaw. This tumor makes aggressive invasions and has a high recurrence rate. This study aimed to investigate the differentially expressed genes (DEGs), biological function alterations, disease targets, and existing drugs for AM using bioinformatics analysis.

Methods

The data set of AM was retrieved from the GEO database (GSE132474) and identified the DEGs using bioinformatics analysis. The biological alteration analysis was applied to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Protein-protein interaction (PPI) network analysis and hub gene identification were screened through NetworkAnalyst. The transcription factor-protein network was constructed via OmicsNet. We also identified candidate compounds from L1000CDS2 database. The target of AM and candidate compounds were verified using docking simulation.

Results

Totally, 611 DEGs were identified. The biological function enrichment analysis revealed glycosaminoglycan and GABA (γ-aminobutyric acid) signaling were most significantly up-regulated and down-regulated in AM, respectively. Subsequently, hub genes and transcription factors were screened via the network and showed FOS protein was found in both networks. Furthermore, we evaluated FOS protein to be a therapeutic target in AMs. Candidate compounds were screened and verified using docking simulation. Tanespimycin showed the greatest affinity binding value to bind FOS protein.

Conclusions

This study presented the underlying molecular mechanisms of disease pathogenesis, biological alteration, and important pathways of AMs and provided a candidate compound, Tanespimycin, targeting FOS protein for the treatment of AMs.

METTL1 facilitates ameloblastoma invasive growth via MAPK signaling pathway

OBJECTIVES

Ameloblastoma (AM), a common odontogenic epithelial tumor, exhibits aggressive growth due to incomplete encapsulation within the jawbone. Postoperative recurrence is a significant concern, closely associated with its invasive nature. We investigate the role of tRNA N-7 methylguanosine (m7G) modification mediated by Methyltransferase-like 1 (METTL1) in AM's invasive growth and prognosis.

MATERIALS AND METHODS

METTL1 expression was analyzed in diverse cell lines and clinical AM tissues. Its association with postoperative AM recurrence was examined. Functional experiments included METTL1 gene silencing using shRNA in hTERT-AM cells, assessing cell proliferation, migration, and invasion. Xenograft tumor model was constructed to investigate tumor growth. Molecular mechanisms behind METTL1's role in AM invasiveness were elucidated using Ribosome nascent-chain complex-bound mRNA sequencing (RNC-seq) and experimental analysis.

RESULTS

High METTL1 expression was significantly associated with postoperative recurrence in AM. The inhibition of AM development following METTL1 knockdown has been corroborated by experiments conducted both in vitro and in vivo. Analysis of RNC-seq data revealed that downregulated genes were predominantly enriched in the mitogen-activated protein kinase (MAPK) signaling pathway, suggesting that METTL1 may promote AM's invasive growth through the MAPK signaling pathway.

CONCLUSION

Our study elucidates the functional role of METTL1 in AM's invasive development and prognosis. High METTL1 expression is linked to postoperative recurrence, and METTL1 appears to promote AM invasiveness through the MAPK signaling pathway. These findings contribute to a better understanding of AM pathogenesis and may guide future therapeutic strategies.

Neoadjuvant BRAF-targeted therapy for ameloblastoma of the mandible: an organ preservation approach

BACKGROUND

Ameloblastoma is a rare odontogenic neoplasm frequently located in the mandible. Standard treatment involves radical bone resection and immediate reconstruction, causing functional, aesthetic, and psychological impairments. The BRAF V600E mutation is present in approximately 80% of mandible ameloblastomas, and BRAF inhibitors have demonstrated sustained responses in unresectable cases.

METHODS

We identified ameloblastoma patients planned for ablative surgery and screened them for BRAF V600E mutation. Neoadjuvant BRAF inhibitors were offered to facilitate jaw preservation surgery. Retrospective data collection encompassed treatment regimens, tolerability, tumor response, and conversion to mandible preservation surgery.

RESULTS

Between 2017 and 2022, a total of 11 patients received dabrafenib (n = 6) or dabrafenib with trametinib (n = 5). The median age was 19 (range = 10-83) years. Median treatment duration was 10 (range = 3-20) months. All (100%) patients achieved a radiological response. Ten (91%) patients successfully converted to mandible preservation surgery with residual tumor enucleation. One patient attained complete radiological response, and surgery was not performed. Among the 10 surgically treated patients, all exhibited a pathological response, with 4 achieving near complete response and 6 partial response. At a median follow-up of 14 (range = 7-37) months after surgery, 1 case of recurrence was observed. Grade 1-2 adverse effects were reported in 8 (73%) patients, with a single case of grade 3 (hepatitis). Dose modification was necessary for 3 patients, and 4 experienced treatment interruptions, while 1 patient permanently discontinued therapy.

CONCLUSIONS

Neoadjuvant BRAF inhibition may offer a safe and effective strategy for organ preservation in mandible ameloblastoma treatment.

Exploring protein profiles and hub genes in ameloblastoma

Ameloblastoma (AM) is a prominent benign odontogenic tumor characterized by aggressiveness, likely originating from tooth-generating tissue or the dental follicle (DF). However, proteomic distinctions between AM and DF remain unclear. In the present study, the aim was to identify the distinction between AM and DF in terms of their proteome and to determine the associated hub genes. Shotgun proteomics was used to compare the proteomes of seven fresh-frozen AM tissues and five DF tissues. Differentially expressed proteins (DEPs) were quantified and subsequently analyzed through Gene Ontology-based functional analysis, protein-protein interaction (PPI) analysis and hub gene identification. Among 7,550 DEPs, 520 and 216 were exclusive to AM and DF, respectively. Significant biological pathways included histone H2A monoubiquitination and actin filament-based movement in AM, as well as pro-B cell differentiation in DF. According to PPI analysis, the top-ranked upregulated hub genes were ubiquitin C (UBC), breast cancer gene 1 (BRCA1), lymphocyte cell-specific protein-tyrosine kinase (LCK), Janus kinase 1 and ATR serine/threonine kinase, whereas the top-ranked downregulated hub genes were UBC, protein kinase, DNA-activated, catalytic subunit (PRKDC), V-Myc avian myelocytomatosis viral oncogene homolog (MYC), tumor protein P53 and P21 (RAC1) activated kinase 1. When combining upregulated and downregulated genes, UBC exhibited the highest degree and betweenness values, followed by MYC, BRCA1, PRKDC, embryonic lethal, abnormal vision, Drosophila, homolog-like 1, myosin heavy chain 9, amyloid beta precursor protein, telomeric repeat binding factor 2, LCK and filamin A. In summary, these findings contributed to the knowledge on AM protein profiles, potentially aiding future research regarding AM etiopathogenesis and leading to AM prevention and treatment.

It was not possible to detect BRAF V600E mutation in circulating cell-free DNA from patients with ameloblastoma: A diagnostic accuracy study

BACKGROUND

The objective of this study is to evaluate the diagnostic accuracy of plasma-based liquid biopsy for the detection of the BRAF V600E mutation in circulating cell-free DNA from patients with ameloblastoma.

METHODS

This is a prospective diagnostic accuracy study conducted based on the Standards for Reporting Diagnostic Accuracy recommendations. The index test was the plasma-based liquid biopsy, whereas the reference standard was the conventional tissue biopsy. The target condition was the detection of BRAF V600E mutation. The study population consisted of individuals with ameloblastoma recruited from three tertiary hospitals from Brazil. A negative control group composed of three individuals with confirmed wild-type BRAF lesions were included. The participants underwent plasma circulating cell-free DNA and tumor tissue DNA isolation, and both were submitted to using competitive allele-specific TaqMan™ real-time polymerase chain reaction technology mutation detection assays. Sensitivity and specificity measures and positive and negative predictive values were calculated.

RESULTS

Twelve patients with conventional ameloblastoma were included. BRAF V600E mutation was detected in 11/12 (91.66%) ameloblastoma tissue samples. However, the mutation was not detected in any of the plasma-based liquid biopsy circulating cell-free DNA samples in both ameloblastomas and negative control group. The sensitivity and specificity of plasma-based liquid biopsy for the detection of the BRAF V600E mutation in circulating cell-free DNA was 0.0 and 1.0, respectively. The agreement between index test and reference standard results was 26.66%.

CONCLUSION

Plasma-based liquid biopsy does not seem to be an accurate method for the detection of the BRAF V600E mutation in circulating circulating cell-free DNA from patients with ameloblastoma, regardless of tumor size, anatomic location, recurrence status, and other clinicopathological features.

Immunohistochemical analysis of p53 and p63 in selected odontogenic cysts and tumours

Background

It is a well-recognized fact that abnormal cell proliferation plays a crucial role in the development of odontogenic lesions. p53 is a tumour-suppressor gene which assists in cell cycle regulation and p63 is a homolog of p53 responsible for ectodermal differentiation and maintenance of stratified epithelial progenitor-cell. Analysing the tissue expression of p53 and p63 in odontogenic lesions may provide us with an insight into their potential role in the development of these lesions.

Objective

The objective is to study the expression of p53 and p63 in selected odontogenic lesions using immunohistochemistry.

Materials and Methods

Formalin-fixed paraffin-embedded tissues of 15 ameloblastomas, 10 adenomatoid odontogenic tumours (AOT), 15 odontogenic keratocysts (OKCs), 10 dentigerous cysts (DCs) along with 10 cases of normal mucosa were retrieved from the departmental archives. These specimens were then subjected to immunohistochemical staining using p53 and p63 oncoproteins.

Results

p53 and p63 immune-expression showed mainly intranuclear localization. The mean positivity of p53 in ameloblastoma (59.45%) and OKC (26.38%) was significantly higher than AOT (6.77%) and DC (4%). In contrast, there was no significant difference in the positivity of p63 in between ameloblastoma (77.55%), AOT (69.50%), OKC (76.47%), and DC (50.69%).

Conclusion

p53 expression can be correlated with the clinical behaviour of the odontogenic lesions and it can be used as a prognostic marker in odontogenic cysts and tumours. In contrast, p63 expression does not corelate with the biological behaviour of odontogenic lesions.

Unicystic ameloblastoma: A retrospective study on recurrent factors from a single institute database

OBJECTIVE

Unicystic ameloblastomas are a variant of ameloblastoma with a definite recurrence rate because of the biological behaviours of the tumour. The risk factors associated with disease recurrence were analysed in this retrospective study.

METHODS

A total of 132 patients with primary unicystic ameloblastoma reported in a tertiary hospital from 2005 to 2015 were analysed to identify the clinic-pathological and radiological factors associated with recurrence using univariate and multivariate Cox regression analyses.

RESULTS

The mean volume was 30.54cm3 ± 12.55 cm3, and this value differed significantly according to recurrence (p < 0.001). Root resorption and bone cortex/soft tissue invasion were also significantly associated with recurrence among unicystic ameloblastoma patients (p = 0.017 vs. p < 0.001, respectively). A new stage classification system was developed to predict disease recurrence of patients. The multivariate Cox regression analysis revealed that the new stage classification system was the only predictor of disease recurrence in unicystic ameloblastoma patients (p < 0.001), regardless of root resorption, position and site characteristics.

CONCLUSIONS

Volume, root resorption and bone cortex/soft tissue invasion were risk factors for disease recurrence among unicystic ameloblastoma patients. The new stage classification was an independent predictor of disease recurrence in patients with unicystic ameloblastoma.

Proteomics study of bone tissue around ameloblastoma and the potential mechanism of CD36 in bone remodelling

Ameloblastoma (AM) is characterised by local aggressiveness and bone resorption. To our knowledge, the proteomic profile of bone adjacent to AM has not previously been explored. We therefore looked at the differential proteins in cancellous bone (CB) adjacent to AM and normal CB from the mandible. CB proteins were extracted, purified, quantified, and analysed by liquid chromatography-mass spectrometry (LC-MS) using samples from five patients with AM. These proteins were further investigated using gene ontology for additional functional annotation and enrichment. Proteins that met the screening requirements of expression difference ploidy > 1.5-fold (upregulation and downregulation) and p < 0.05 were subsequently deemed differential proteins. Immunohistochemical staining was performed to confirm the above findings. Compared with normal mandibular CB, 151 differential proteins were identified in CB adjacent to the mandibular AM. These were mainly linked to cellular catabolic processes, lipid metabolism, and fatty acids (FA) metabolism. LC-MS and immunohistochemistry showed that CD36 was one of the notably decreased proteins in CB bordering the AM compared with normal mandibular CB (p = 0.0066 and p = 0.0095, respectively). CD36 expression in CB correlates with bone remodelling in AM, making CD36 a viable target for therapeutic approaches.

Curettage combined with decompression for the treatment of ameloblastoma in children: report of two cases

BACKGROUND

Ameloblastoma (AM) is the most common benign odontogenic tumor, which is more often detected in the mandible than maxilla, especially the mandibular body and mandibular angle. Pediatric AM is a rare disease, especially in patients aged 10 and younger. Compared with the mainstream osteotomy and reconstructive surgery for adult ameloblastoma, there is more room for discussion in the treatment of pediatric ameloblastoma. The postoperative functional and psychological influence can not be ignored. Especially for children in the period of growth and development, an osteotomy is often challenging to be accepted by their parents. We report two patients with ameloblastoma under 10 years old who are treated with curettage and fenestration, which is a beneficial method for children with ameloblastoma.

CASE PRESENTATION

We present two cases of classic ameloblastoma in children. We describe in detail the patients' characteristics, treatment processes, and follow-up result. The bone formation and reconstruction in the lesion area after fenestration decompression and curettage are recorded at every clinic review. The surgical details and principles of curettage and decompression are also described and discussed. The two patients have good bone shape recovery and no recurrence.

CONCLUSIONS

Children are in the growth and development period and possess an extremely strong ability of bone formation and reconstruction. Based on the principles of minimally invasive and functional preservation, we believe that curettage combined with decompression can be the first choice for treating AM in children, especially for mandibular lesions.

BRAF p.V600E Mutational Status Does Not Correlate with Biological Behavior in Conventional Ameloblastomas: A Disease-Free Survival Analysis

BACKGROUND

Dysregulation of the MAPK pathway appears to exert a pivotal role in the pathogenesis of ameloblastomas, since BRAF p.V600E has been reported in over 65% of the tumors. Therefore, the purpose of this study was to investigate whether the BRAF p.V600E is related to biological behavior and disease-free survival in patients with conventional ameloblastomas.

METHODS

This is a retrospective cohort study based on the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) recommendations. The study population consisted of individuals treated for conventional ameloblastomas. Clinical, imaging, histomorphological, immunohistochemical (Ki67 and CD138/syndecan-1), and molecular BRAF p.V600E mutation analyses were performed. Bivariate statistical analysis was performed through chi-square and Fisher's exact tests. Kaplan-Meier analysis with log-rank test and Cox proportional hazards regression were used to identify predictors of disease-free survival, with a significance level of 5%.

RESULTS

Forty-one individuals were included, with a male-to-female ratio of 1.15:1. BRAF p.V600E mutation was identified in 75.6% of the tumors. No association between the BRAF mutational status and other clinical, imaging, histomorphological, and immunohistochemical variables was observed. Only the initial treatment modality was significantly associated with a better prognosis in univariate (p = 0.008) and multivariate (p = 0.030) analyses, with a hazard ratio of 9.60 (95%IC = 1.24-73.89), favoring radical treatment.

CONCLUSION

BRAF p.V600E mutation emerges as a prevalent molecular aberration in ameloblastomas. Nevertheless, it does not seem to significantly affect the tumor proliferative activity, CD138/syndecan-1-mediated cell adhesion, or disease-free survival outcomes.

Engineering models of head and neck and oral cancers on-a-chip

Head and neck cancers (HNCs) rank as the sixth most common cancer globally and result in over 450 000 deaths annually. Despite considerable advancements in diagnostics and treatment, the 5-year survival rate for most types of HNCs remains below 50%. Poor prognoses are often attributed to tumor heterogeneity, drug resistance, and immunosuppression. These characteristics are difficult to replicate using in vitro or in vivo models, culminating in few effective approaches for early detection and therapeutic drug development. Organs-on-a-chip offer a promising avenue for studying HNCs, serving as microphysiological models that closely recapitulate the complexities of biological tissues within highly controllable microfluidic platforms. Such systems have gained interest as advanced experimental tools to investigate human pathophysiology and assess therapeutic efficacy, providing a deeper understanding of cancer pathophysiology. This review outlines current challenges and opportunities in replicating HNCs within microphysiological systems, focusing on mimicking the soft, glandular, and hard tissues of the head and neck. We further delve into the major applications of organ-on-a-chip models for HNCs, including fundamental research, drug discovery, translational approaches, and personalized medicine. This review emphasizes the integration of organs-on-a-chip into the repertoire of biological model systems available to researchers. This integration enables the exploration of unique aspects of HNCs, thereby accelerating discoveries with the potential to improve outcomes for HNC patients.

Single-cell transcriptomics reveals cell atlas and identifies cycling tumor cells responsible for recurrence in ameloblastoma

Ameloblastoma is a benign tumor characterized by locally invasive phenotypes, leading to facial bone destruction and a high recurrence rate. However, the mechanisms governing tumor initiation and recurrence are poorly understood. Here, we uncovered cellular landscapes and mechanisms that underlie tumor recurrence in ameloblastoma at single-cell resolution. Our results revealed that ameloblastoma exhibits five tumor subpopulations varying with respect to immune response (IR), bone remodeling (BR), tooth development (TD), epithelial development (ED), and cell cycle (CC) signatures. Of note, we found that CC ameloblastoma cells were endowed with stemness and contributed to tumor recurrence, which was dominated by the EZH2-mediated program. Targeting EZH2 effectively eliminated CC ameloblastoma cells and inhibited tumor growth in ameloblastoma patient-derived organoids. These data described the tumor subpopulation and clarified the identity, function, and regulatory mechanism of CC ameloblastoma cells, providing a potential therapeutic target for ameloblastoma.

Prognostic value of the expression and localization of cell proliferation and apoptosis markers in unicystic ameloblastomas

The aim of this study was to verify whether the expression of cell proliferation and apoptosis markers in different types of unicystic ameloblastoma (UA) is associated with the location of neoplastic cells. Immunohistochemical study with a sample of 32 cases of UA, 11 cases of conventional ameloblastoma (CAM) and ten dental follicles (DF) cases was performed. Cell proliferation was assessed using Ki-67 status, and apoptosis by caspase-3 expression. Mural UA (MUA) showed a higher immunostaining of Ki-67 (p < 0.05) and a lower immunostaining of Caspase-3 (p < 0.05) compared with luminal and intraluminal subtypes of UA and CAM. The neoplastic cells of the MUA's cystic capsule showed a higher expression of Ki-67 protein (p < 0.0001) and a lower expression of Caspase-3 (p < 0.0001) compared with the lumen. DF showed lower Ki-67 and Caspase-3 immunostaining (p < 0.05) than neoplasms. The higher immunoexpression of Ki-67 and the lower immunoexpression of Caspase-3 in MUA, in the parenchyma cells within the cystic capsule, suggest an association between the biological behaviour and location of neoplastic cells in a tumour.