Treatment of ameloblastoma and ameloblastic carcinoma with radiotherapy

BRAF mutation in five cases of sinonasal ameloblastic tumors and their clinical course: a case report

BACKGROUND

Sinonasal ameloblastic tumors exhibit unique clinical, pathological, and genetic traits distinct from mandibular bone cases, accounting for the majority of ameloblastic tumors. Recent findings emphasize a notable genetic disparity, showing high BRAF mutation rates in mandibular cases versus very low rates in maxillary cases.

CASE PRESENTATION

We analyzed five sinonasal ameloblastic tumor cases treated at Kyushu University Hospital. All patients were Japanese, four male and one female, and their age ranged from 43 to 73 years. Three were diagnosed with ameloblastoma, with one experiencing recurrence that progressed to a life-threatening condition owing to the lack of effective treatment. One patient was histologically diagnosed as ameloblastic carcinoma, and another patient, although histologically diagnosed as ameloblastoma, presented with lymph node metastasis, confirming it as a metastasizing ameloblastoma with clinical malignancy. Local radical resection was performed in all five patients; however, three of them had positive resection margins, and two received postoperative (chemotherapy) radiation therapy. Recurrence was confirmed in two patients, with one patient undergoing chemoradiation therapy and achieving local control. BRAF mutations were detected in only one patient.

CONCLUSION

Owing to anatomical challenges in achieving negative resection margins and the low BRAF mutation frequency, sinonasal ameloblastic tumors exhibit poor prognosis with high recurrence, malignancy, and metastasis rates. When factors predicting recurrence post-radical resection in these tumors are identified, chemoradiation therapy is recommended as an adjuvant postoperative treatment. However, it should be noted that this presentation of adjuvant therapy is based on the experience of only five cases.

Digital technology-enhanced reconstruction and rehabilitation following mandible fibular flap grafting with implants: a case report

Objective

In this paper, we report a case of missing posterior teeth after mandibular fibular flap grafting and implant restoration by means of a digital restorative process, in the hope that the application of digital technology will help the patient to comfortably establish an adapted occlusal relationship.

Case report

A 29-year-old male patient developed a left mandibular ameloblastoma measuring 35 mm × 35 mm × 25 mm, which did not invade the surrounding bone tissue, submandibular gland tissue, or lymph nodes. After resection of an 85 mm mandibular segment, the patient was reconstructed using a gastrocnemius flap transfer. He was then referred to our institution for postoperative dental implant restoration. The restorative process incorporated various digital technologies including a digital facebow, intraoral scanner, extraoral scanner, facial scanner, and CAD/CAM systems. Following 1 year post-implantation, the patient received second-stage implantation alongside autologous dermal allograft (ADM) transplantation; subsequently, a temporary prosthesis was fabricated while employing an electronic articulator to accurately transfer occlusal relationships before finalizing with permanent restorations. The integration of digital technology throughout this restorative process enhanced both precision and comfort.

Conclusions

This case study offers an innovative and efficient clinical approach for addressing dentition defect following mandibular reconstruction via advanced digital methodologies.

From pathogenesis to precision medicine: Transformative advances in research and treatment of ameloblastoma

Odontogenic neoplasms of the jaw are dominated by ameloblastoma (AM), a locally aggressive epithelial tumor with a significant propensity for recurrence. The World Health Organization's 2022 update to the AM classification system underscores recent progress in comprehending its underlying mechanisms and refining clinical approaches. Contemporary research has yielded significant insights into the genetic underpinnings of AM, paving the way for the development of precision-based treatment strategies. Advanced genetic profiling has revealed a significant frequency of BRAF (V-raf murine sarcoma viral oncogene homolog) V600E and SMO (Smoothened) gene alterations in AM. Importantly, therapeutic interventions specifically designed to target these genetic aberrations, including BRAF and MEK pathway blockers, have shown encouraging results in terms of both effectiveness and tolerability, as documented in individual case reports and small-scale clinical investigations. This comprehensive review summarizes the recent modifications to the World Health Organization's categorization of AMs, explores progress in elucidating their underlying molecular pathways, and evaluates emerging targeted treatment modalities. Our objective is to present a thorough synthesis of contemporary scientific discoveries and therapeutic interventions, potentially paving the way for more efficacious and individualized clinical management protocols for this complex neoplasm.

Exploring treatment complexity in maxillary ameloblastoma: A case study on the efficacy of radiotherapy with transcriptomic and literature insights

In this report, we describe the case of a patient initially experiencing symptoms including nasal obstruction and rhinorrhoea, leading to surgeries and a diagnosis of ameloblastoma. Despite complete surgical resections, MRI follow-ups indicated tumour regrowth, prompting a shift to radiotherapy. The treatment plan involved a high-dose (60Gy in 30 fractions of 2Gy) volumetric modulated arc therapy. During treatment, the patient experienced minimal side effects and showed significant clinical improvement, including tumour size reduction and resolution of facial paralysis. Follow-up MRI confirmed shrinkage of the tumour, with some persistent symptoms like diplopia. To better understand the radiosensitivity of ameloblastomas, transcriptomic analysis highlighted the potential of a radiosensitivity index to predict treatment response, indicating ameloblastomas exhibit higher radiosensitivity compared to odontogenic keratocysts. Finally, literature analysis showed a small number of cases with wide range of radiation dose. In conclusion, the case illustrates the complex diagnostic journey of ameloblastomas and underscores the efficacy of radiotherapy for inoperable cases, and the importance of predictive biomarkers to enhance treatment outcomes.

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.

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.

Malignant transformation of primary ameloblastoma of skull: case report and review of current literature

Background

Since 1964, there has been a scarcity of reported cases of primary ameloblastoma (AM) or ameloblastic carcinoma (AMCa) of the skull. The clinical presentation and distinctive features of this uncommon condition at specific anatomical sites remain unclear. We report a case of malignant transformation of a primary AM of the skull situated in the frontal-temporal-parietal region and highlight its similarities to other cases reported in the literature.

Clinical presentation

A 53-year-old female patient presented with a 20-day history of headaches and bilateral lower limb weakness for 10 days. Physical examination revealed slow and unsteady gait. An occupying lesion was observed in the right frontal-temporal-parietal region of the skull on the Cranial imaging. A right cranial bone tumor margin expansion resection was performed. The patient's motor functions recovered normally after surgery. Postoperative imaging examinations showed10 tumor resection. Follow-up imaging examinations showed tumor recurrence. The patient underwent resection of the recurrent tumor. Postoperative pathological analysis revealed malignant transformation of the AM.Follow-up imaging examinations showed tumor recurrence again. The patient was admitted for stereotactic radiotherapy. Follow-up imaging examinations demonstrated no evidence of tumor recurrence and subsequent chest CT revealed no signs of metastasis.

Conclusion

Primary AM or AMCa of the skull is increasingly being described in the literature, but detailed reports on the malignant transformation of primary AM of the skull are lacking. The pathogenesis of this condition remains unclear. Aggressive treatment and close follow-up may be crucial for preventing disease recurrence and malignant transformation.

Genomic profiling and precision medicine in complex ameloblastoma

BACKGROUND

Ameloblastoma may present a significant treatment challenge in the locally advanced, recurrent and metastatic setting. Comprehensive genomic profiling (CGP) can identify targetable genomic alterations to aid in treatment.

METHODS

Ameloblastoma samples were sequenced using hybrid-capture based sequencing. A systematic literature review was performed to examine outcomes in studies employing targeted treatment in ameloblastoma.

RESULTS

We reviewed 14 cases of Ameloblastoma using CGP. There were six patients with activating BRAF mutations, five with PIK3CA, five with SMO, four with FGFR2, one with EGFR, and one with ROS1. All cases were MSI stable and the median TMB was 2.5 mutations/Mb. A separate literature review of clinical outcomes in ameloblastoma showed a predominance of at least partial response to targeted treatment (7/12 cases).

CONCLUSION

CGP is helpful in identifying specific driver mutations in patients with complex ameloblastoma. Targeted treatment has been employed with success in achieving treatment response.

BRAF V600E Mutation in Ameloblastoma: A Systematic Review and Meta-Analysis

The discovery that ameloblastoma has a high mutation incidence of BRAF V600E may enable a better investigation of pathophysiology. However, there is inconsistent evidence regarding this mutation occurrence and its association with clinical information. This systematic review and meta-analysis aim to pool the overall mutation prevalence of BRAF V600E in reported ameloblastoma cases and to determine its association with patient demographic and clinicopathological features. Following the PRISMA guidelines, a comprehensive article search was conducted through four databases (Scopus, Google Scholar, PubMed, and Web of Science). Seventeen articles between 2014 and 2022 met the inclusion criteria with 833 ameloblastoma cases. For each included study, the significance of BRAF V600E on the outcome parameters was determined using odd ratios and 95% confidence intervals. Meta-analysis prevalence of BRAF V600E in ameloblastoma was 70.49%, and a significant meta-analysis association was reported for those younger than 54 years old and in the mandible. On the contrary, other factors, such as sex, histological variants, and recurrence, were insignificant. As a result of the significant outcome of BRAF V600E mutation in ameloblastoma pathogenesis, targeted therapy formulation can be developed with this handful of evidence.

Managing stage 4 ameloblastoma with dual BRAF/MEK inhibition: A case report with 8-year clinical follow-up

We present 8-year follow-up on the first patient with stage 4 ameloblastoma carrying a BRAF V600E mutation treated with dual BRAF/MEK inhibition (BRAF/MEKi). He experienced a durable clinical response while on dabrafenib (BRAFi) and trametinib (MEKi) without toxicity nor evidence for drug-resistant tumor progression. He was asymptomatic when he self-discontinued therapy after 4 years of sustained clinical response. He did not return for follow-up until 2.5 years later with onset of painful mandibular tumor recurrence associated with recurrent bilateral lung metastases. He was rechallenged with dabrafenib/trametinib and experienced another prompt tumor response and remains in a second durable clinical remission (currently > 16 months) on continuous dual targeted therapy. We discuss the implications of this case study for future treatment strategies.

Carbon ion radiotherapy for recurrent ameloblastoma: A case report

Ameloblastoma is a kind of benign, odontogenic tumor of epithelial origin, and surgery is mainstay treatment method; however, recurrence is common, and usually the treatment for recurrence is still surgery. We report on a patient of recurrent ameloblastoma treated with carbon ion radiation therapy and achieved a good efficacy. A 25-year-old female with relapse of an ameloblastoma was referred to the Wuwei Heavy Ion Center for carbon ion therapy. She had been initially diagnosed with ameloblastoma 8 years ago and underwent operation of right mandible ameloblastoma. After she transferred to our center, she accepted a dose of 60 GyE carbon ion radiation therapy, and the efficacy is good. Carbon ion radiation therapy can be an effective treatment option for ameloblastoma.

Innocuous presentation of ameloblastic carcinoma

Ameloblastic carcinoma is a rare malignant odontogenic neoplasm that exhibits diverse clinical and radiological presentations. In fact there are several differential diagnoses during histopathological evaluation too. Lack of adequate reports could not establish the predominant demographic, clinical and radiological presentations. For the same reasons, the role of adjuvant radiotherapy and chemotherapy is also unsubstantiated yet. This case discusses the innocuous clinical and radiological presentation of ameloblastic carcinoma in a 55-year-old man where the diagnostic confirmation was achieved through histopathological evaluation. The differential diagnoses, treatment and follow-up details of this case are discussed in light of the previous published case reports and systematic reviews of case reports in an attempt to increase the sensitisation among dentists towards ameloblastic carcinoma.

Comparative transcriptional profiling of canine acanthomatous ameloblastoma and homology with human ameloblastoma

Ameloblastomas are odontogenic tumors that are rare in people but have a relatively high prevalence in dogs. Because canine acanthomatous ameloblastomas (CAA) have clinicopathologic and molecular features in common with human ameloblastomas (AM), spontaneous CAA can serve as a useful translational model of disease. However, the molecular basis of CAA and how it compares to AM are incompletely understood. In this study, we compared the global genomic expression profile of CAA with AM and evaluated its dental origin by using a bulk RNA-seq approach. For these studies, healthy gingiva and canine oral squamous cell carcinoma served as controls. We found that aberrant RAS signaling, and activation of the epithelial-to-mesenchymal transition cellular program are involved in the pathogenesis of CAA, and that CAA is enriched with genes known to be upregulated in AM including those expressed during the early stages of tooth development, suggesting a high level of molecular homology. These results support the model that domestic dogs with spontaneous CAA have potential for pre-clinical assessment of targeted therapeutic modalities against AM.

Rare Ameloblastic Carcinoma Metastasis to the Cervical Spine: A Case Report

BACKGROUND AND IMPORTANCE

Ameloblastic carcinoma (AC) is a malignant neoplasm of epithelial origin that typically arises from the mandible or maxilla. It represents approximately 2% of all odontogenic tumors. Gross total resection is the surgical goal given AC's aggressiveness and propensity for recurrence. We present the first reported AC metastasis to the cervical spine.

CLINICAL PRESENTATION

A 61-yr-old African American female with a history of AC of bilateral mandibles and lung metastases presented with neck pain and right arm weakness progressive over several months. Cervical spine imaging demonstrated a cervical 3 pathological fracture with severe anterior vertebral body compression and resultant cervical 2-3 kyphotic deformity and bony retropulsion causing severe cord compression. The patient underwent a cervical 3 corpectomy and cervical 2-4 anterior fixation followed by a cervical 3 laminectomy and cervical 2-5 dorsal internal fixation and fusion. Postoperatively, the patient's neurological exam remained stable and imaging showed improved spinal alignment and appropriate anterior and posterior instrumentation. Unfortunately, the patient thereafter suffered a decline in performance status and progression of lung metastatic disease. Her oncology team is considering chemotherapy and stereotactic radiosurgery, but her prognosis remains grim.

CONCLUSION

AC is a rare and aggressive pathology with a poor prognosis despite multimodal therapy. We present the first case of AC metastatic spread to the spine. We aim to bring this pathology to the attention of our worldwide neurosurgical colleagues and share our surgical approach and multidisciplinary management to assist those who may encounter this pathology in the future.

Comparison of Immunohistochemistry and DNA Sequencing for BRAF V600E Mutation Detection in Mandibular Ameloblastomas

This study aimed to investigate the presence of BRAF V600E mutation in mandibular ameloblastoma by comparing the results of molecular detection and immunohistochemical analysis. A 128 cases of mandibular ameloblastoma and 30 cases of dentigerous cyst (control group) were selected for analysis. Detection of BRAF V600E mutation was performed with immunohistochemistry (IHC) and polymerase chain reaction techniques. Clinico-pathologic data were collected in order to investigate possible associations with the mutation. Of the 128 cases submitted to IHC, 81.2% (108 cases) showed positivity for anti-BRAF V600E antibody, whereas 24 were negative (18.8%). Molecular analysis of the BRAF V600E mutation by polymerase chain reaction was possible in 116 cases due to DNA quality. Of these cases, 96 were positive (82.8%) and 20 negative (17.2%). All cases of dentigerous cyst were negative for BRAF V600E mutation in both techniques. Considering the sequencing as a gold standard method, the receiver operating characteristics curve analysis showed sensitivity of 0.99 and specificity of 1 (area under the curve=0.995, standard error=0.006; P<0.001; 95% confidence interval=0.983 to 1). We also tested the agreement between the techniques by using the Cohen's κ coefficient, with κ being 0.97 (P<0.001). IHC is a reliable test for identifying the BRAF V600E mutation in ameloblastomas, presenting advantages such as being more frequently used in surgical pathology laboratories and requiring fewer critical steps for paraffin-embedded tissue compared with molecular biology techniques.

Enucleation and surgical stent as a treatment strategy for a large unicystic ameloblastoma: Case report and review of literature

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Ameloblastoma has a locally invasive and aggressive nature and high recurrence rate.

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A conservative approach and a radical resection approach have been suggested.

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Radical resection may lead to esthetic, functional, and psychological sequelae.

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First use of surgical stent with conservative management for ameloblastoma.

Introduction

Ameloblastoma is a benign neoplasm of odontogenic origin with local invasive characteristics and a high recurrence rate. It compromised 1% of the jaw's cysts and tumors with only 10–15% in children.

Presentation of case

A 14-year-old boy sought treatment for a painless swelling involving the right side of the face started one year ago. The intra-oral examination displayed a firm mass associated with 46, 47 teeth, and the angle of the mandible. The radiographic examination revealed a large well-defined homogeneous radiolucency extending from the 46 region to involve the angle and extending towards the coronoid and condylar processes. An incisional biopsy confirmed the diagnosis of unicystic ameloblastoma. Treatment was planned according to the patient’s age: Phase I: Surgical enucleation. Phase II: Construction and insertion of a surgical stent. Phase III: Construction of a transitional acrylic Kennedy class II partial denture. Phase IV: the patient is scheduled for a definitive implant-supported prosthesis at 18 years old.

Discussion

The management of ameloblastoma is influenced by the age of the patient, the extension, duration, and position of the lesion, and the histopathological variants. Several authors recommended enucleation as a conservative treatment approach to eliminate the esthetical, functional, and psychological squeals associated with the radical approach. The use of a surgical stent protects the enucleated cavity and promote tissue healing.

Conclusion

Enucleation and subsequent surgical stent not only eliminates the disease, but also preserves the bone structure, prevents the facial disfigurement, and significantly improve the patient’s esthetic, mastication, oral health, and quality of life.

Pure endoscopic transsphenoidal treatment of skull base ameloblastoma with intracranial extension: Case report and literature review

Background:

Ameloblastoma is a benign locally invasive lesion that represents 1% of all oral tumors. Epidemiological characteristics are variable in the literature. The most common origin sites are mandible and maxilla. Rarely presents metastasis, but the skull base, lymph nodes, and the lung are described as metastatic sites. Low recurrence rates were reported by the authors when surgical treatment achieved complete resection.

Case Description:

A female patient, 19 years old presenting moderate headache associated with nausea, vomiting, left facial hypoesthesia, and low visual acuity. Resonance image showed a heterogeneous expansive solid formation in sphenoid bone and clivus with neoplastic aspect. Signs of dissemination due to contiguity and invasion of skull base structures, especially cavernous sinus and internal carotid artery, determining also compression of the brainstem. First, an endoscopic biopsy was performed with otorhinolaryngology service. The pathological study showed histological characteristics of ameloblastoma. After, the patient was submitted to endoscopic surgery for resection of tumor.

Conclusion:

Ameloblastoma is a rare tumor with benign behavior and slow growing. It arises from odontogenic epithelium and accounts 1% of all oral tumors. The mandible and maxilla are the most common sites of origin. Ameloblastoma with intracranial involvement is a rare presentation with few literature reviews. A long time illness course and multiple surgeries are characteristics present in the majority of cases described. Total resection surgery is the treatment of choice and endoscopic transnasal resection is a viable option.

A Rare Presentation of Ameloblastic Carcinoma of the Sinus Cavity and Skull Base

Ameloblastic carcinoma (AC) is an exceedingly rare odontogenic cancer about which there is limited information in the literature. We present a case of AC originating in the sinus cavity and extending to the skull base in a patient in the first trimester of pregnancy. Diagnostic work up was complicated by this pregnancy, which delayed radiation exposure with imaging. Once scans were obtained, diagnosis was further complicated by the radiographic similarities between possible lung metastases and previously undiagnosed sarcoid nodules. After thorough work up to rule out metastatic disease, the patient was successfully treated with primary surgical resection followed by adjuvant chemoradiation. The patient remained disease free at one year after therapy. This case demonstrates the importance of thorough work up in the diagnosis of AC, and is an opportunity to review the literature and discuss therapeutic methods to treat this rare, aggressive neoplasm.

MAID chemotherapy regimen as a treatment strategy for metastatic malignant ameloblastoma: A case report

RATIONALE

Ameloblastoma is generally characterized as a benign tumor originating in odontogenic epithelium. However, few cases of metastatic malignant ameloblastoma have also been reported. Due to the low incidence of malignant ameloblastoma, there is no established treatment regimen. To explore effective treatment for malignant ameloblastoma, we reported this case study.

PATIENTS CONCERNS

This report described a case of a 28-year-old malignant ameloblastoma female patient with multiple metastasis (brain and lung).

DIAGNOSES

The patient presented ameloblastoma of the left mandible in 2012. Three years later, local recurrence and brain metastasis was observed during a follow-up examination. Five years later, malignant ameloblastoma was detected by imaging and immunohistochemistry in the bilateral multiple pulmonary nodules and mediastinal lymph nodes.

INTERVENTIONS

The patient was initially treated with tumor resection. Three years later after local recurrence and brain metastasis, she was accepted the extensive mandibulectomy supplemented with brain stereotactic body radiotherapy (SBRT). When diagnosed with pulmonary metastasis, the patient received combined chemotherapy regimen of MAID (mesna, adriamycin, ifosfamide and dacarbazine) for 6 cycles.

OUTCOMES

The efficacy evaluation was partial remission (PR) after the 6 cycles of MAID. The last patient follow-up was July 24th 2018, and no evidence of progression was observed. The progression-free survival (PFS) of the patient was more than 9 months.

LESSONS

Surgical resection is the optimal treatment for locally recurrent ameloblastoma. SBRT may be an effective treatment for unresectable oligometastasis of malignant ameloblastoma. Finally, combined chemotherapy of MAID showed encouraging effects in the management of metastatic malignant ameloblastoma.

Advancements in MAPK signaling pathways and MAPK-targeted therapies for ameloblastoma: A review

Numerous signal transduction pathways are closely associated with the occurrence, development, and prognosis of ameloblastoma (AM). Mitogen-activated protein kinase (MAPK) is a serine/threonine-specific protein kinase that transduces intracellular signals in critical cellular phenomena. A number of recent analyses have reported that the MAPK signaling pathway contributes significantly to AM. High-throughput DNA sequencing methods, such as next-generation sequencing using Illumina have yielded advancements in studies on MAPK signaling pathways and their association with AM; in particular, BRAF V600E is mediated by the activation of the Ras/Raf/MAPK pathway. This review discusses advancements in studies on MAPK signaling pathways and MAPK-targeted inhibitors or antibodies, along with the merits and demerits of MAPK-targeted therapies, finally followed by a discussion regarding more efficient potential MAPK-targeted therapies to treat AM with few side effects, thereby providing novel insights into targeted therapy for AM.

Mandibular ameloblastic carcinoma: case report and literature review

Introduction: Ameloblastic carcinoma is an extremely rare malignant odontogenic tumor with predominantly mandibular localization. In most cases, it is treated surgically. Observation: Here, we describe a case of ameloblastic carcinoma. The patient presented a large expansive mass on the ascending branch of the left mandible, which was ulcerated and communicating with the oral cavity. He refused the proposed surgical treatment after being informed of the risk of facial decomposition. After several years, due to progressive symptomatology, he received palliative radiotherapy of 60 Gy divided into 30 sessions. Local control of the disease was achieved. Discussion: The efficiency of radiotherapy for ameloblastic carcinoma remains controversial. Conclusion: Radiotherapy appears to be a second-line approach when surgery is not feasible for ameloblastic carcinoma treatment.

Ameloblastic carcinoma: a clinicopathologic analysis of cases seen in a Nigerian Teaching Hospital and review of literature

Introduction

Ameloblastic carcinoma is a rare malignant odontogenic neoplasm that exhibits histological features of ameloblastoma in combination with cytological atypia. It may arise de novo or secondarily through malignant de-differentiation of pre-existing ameloblastoma or odontogenic cyst. Secondary ameloblastic carcinomas often results from repeated surgical intervention, which is a mainstay of odontogenic tumor management in resource limited settings. To date, relatively few cases of ameloblastic carcinomas have been reported and many cases have been misdiagnosed as ameloblastoma. This is due to its wide range of clinicopathological feature which range from indolent to aggressive. It may present as an aggressive ulcerated mass or as a simple cystic lesion; hence, it often challenging to delineate from its benign counterpart, ameloblastoma.

Methods

this study reviewed the clinicopathological data on 157 cases of odontogenic tumors diagnosed over a 10 years period from the pathology archive of the Oral Pathology Unit of Obafemi Awolowo University Teaching Hospital Complex (OAUTHC), Ile-Ife, Nigeria.

Results

of all these cases, we identified that 64.9% were Ameloblastomas, while 8.3% were ameloblastic carcinomas. Primary subtypes of ameloblastic carcinoma constituted 23.08%, while 69.23% of the cases were of the secondary subtype. We also found that the secondary subtype of ameloblastic carcinomas showed a higher mean duration value of 7.7 years. Most lesions were found in posterior mandible and presented with ulceration, perforation and ill-defined borders radiographically.

Conclusion

this study is among the few that have documented higher frequency of secondary ameloblastic carcinoma in the scientific literature.

Ameloblastomas of the mandible and maxilla

Ameloblastoma is a histologically benign but locally aggressive tumor of the jaws. We conducted a retrospective cohort study to review the clinical, radiologic, and pathologic features of patients with ameloblastoma of the mandible and maxilla and to report the outcomes of treatment. Our study population was made up of a series of 30 consecutively presenting patients-15 men and 15 women, aged 19 to 81 years (median: 61.5)-who had undergone their primary treatment of ameloblastoma of the mandible or maxilla at Memorial Sloan Kettering Cancer Center from January 1987 through December 2012. In addition to demographic data, we compiled information on clinical characteristics, imaging findings, the type of surgery, surgical margins, adjuvant treatments, histologic patterns, length of follow-up, time to recurrence, treatment of recurrence, and factors that had an influence on recurrence. All but 2 patients with negative margins were cured. Favorable outcomes were associated with the administration of adjuvant postoperative radiotherapy for patients with positive margins and a repeat resection for patients with recurrences. Complete excision with negative margins, however, remains the gold standard for curative treatment.

The use of radiation therapy in the definitive management of ameloblastic carcinoma: a case report

Although rare, ameloblastic carcinoma (AC) is one of the most common malignant tumors occurring in the odontogenic epithelium. Evidenced-based medical guidelines for AC are not established because AC is a rare type of cancer. However, surgery for AC is the primary initial treatment modality. A few reports suggest that radiotherapy (RTx) is effective for AC; however, the tumor is generally considered to be radioresistant. Furthermore, if RTx is performed for AC, osteonecrosis may occur because most of the ACs arise from the jaw. Here, we report a case of an older patient with maxillary AC who had underlying medical problems and who received conventional RTx with good outcomes. Ten years after the treatment, no major adverse event accompanying irradiation, local recurrence, or metastasis was observed. We discuss the therapeutic effect and usefulness of RTx on AC. As indicated by our findings, RTx for AC may represent a definitive treatment strategy for patients with poor general conditions or those with tumors that cannot be resected completely.

Proton Beam Therapy for Ameloblastic Carcinoma of the Maxilla: Report of a Rare Case

Ameloblastic carcinoma (AC) is a rare malignant odontogenic tumor that combines the histologic features of ameloblastoma with those of cytologic atypia. The standard treatment for this lesion is wide local excision. Proton beam therapy (PBT) can deliver high irradiation doses to the target and avoid irradiation to surrounding normal tissues, but no reports of PBT for AC have been published thus far. This report describes the case of a 70-year-old woman with a pathologic diagnosis of maxillary AC who refused surgical resection and received hypofractionated PBT at a total dose of 69 Gy in 23 fractions. She has been alive for more than 5 years after PBT without any evidence of recurrence and side effects. This is the first reported case of successful treatment after curative radiation therapy for maxillary AC.

Reconnoitre ameloblastic carcinoma: A prognostic update

AIM

Malignant odontogenic tumor, ameloblastic carcinoma (AC) is challenging to study owing to its rarity, complexity and limited availability of literature. This further makes it difficult to establish its clinical characteristics and prognosis. Our study aimed to evaluate AC's clinico-demographic factors and their relation with prognosis and survival.

MATERIALS AND METHODS

Literature was systematically reviewed for cases pertaining to AC, starting from January 2000 to December 2016. All the required data was obtained, arranged and analysed using Cox regression ratio and Kaplan Meir survival analysis. From the database, 153 cases were retrieved as per the inclusion/exclusion criteria.

RESULTS

The results demonstrated that age of patient, mode of treatment and metastasis affects overall survival. The categorisation of AC as primary or secondary type does not have any role in determining prognosis.

CONCLUSION

Overall survival of AC patient depends upon age, site, treatment and metastasis. For a better prognosis early surgical management of the tumor appears to be the most favourable mode of treatment.

Unresectable Ameloblastoma Successfully Treated with Definitive Proton Therapy

We report the case of an 87-year-old man affected by an unresectable ameloblastoma of the right jaw that was successfully treated by definitive proton therapy up to a dose of 66 Gy in 33 fractions. Treatment was well tolerated, and there were no interruptions due to toxicity. At follow-up visits, the patient experienced complete response to treatment with no evidence of disease and complete recovery from acute side effects. In this report, we discuss the potential and possible pitfalls of proton therapy in the treatment of specific settings.

I125 brachytherapy guided by individual three-dimensional printed plates for recurrent ameloblastoma of the skull base

Ameloblastoma is one of the most common benign odontogenic tumours of the mandible and the maxilla. Wide excision of the tumour is the first choice for treatment (except for unicystic ones). Patients with invaded margins or unresectable lesions may require radiotherapy. Today, permanent implantation of I¹²⁵ seeds is widely used in the treatment of cancer of the head and neck. We report a case of recurrent ameloblastoma of the base of the skull that was treated with I¹²⁵ brachytherapy. The outcome has been encouraging, with total disappearance of the tumour on positron emission tomography 18 months later.

Ameloblastoma: current etiopathological concepts and management

Ameloblastoma is a benign odontogenic tumor of epithelial origin. It is locally aggressive with unlimited growth capacity and has a high potential for malignant transformation as well as metastasis. Ameloblastoma has no established preventive measures although majority of patients are between ages 30 and 60 years. Molecular and genetic factors that promote oncogenic transformation of odontogenic epithelium to ameloblastoma are strongly linked to dysregulation of multiple genes associated with mitogen-activated protein kinase, sonic hedgehog, and WNT/β-catenin signaling pathways. Treatment of ameloblastoma is focused on surgical resection with a wide margin of normal tissue because of its high propensity for locoregional invasion; but this is often associated with significant patient morbidity. The relatively high recurrence rate of ameloblastoma is influenced by the type of molecular etiological factors, the management approach, and how early the patient presents for treatment. It is expected that further elucidation of molecular factors that orchestrate pathogenesis and recurrence of ameloblastoma will lead to new diagnostic markers and targeted drug therapies for ameloblastoma.

BRAF-V600E expression correlates with ameloblastoma aggressiveness

AIMS

The aim of this study was to investigate whether the expression of BRAF-V600E determines an aggressive clinical and molecular presentation of ameloblastoma.

METHODS AND RESULTS

Ninety-three cases of solid ameloblastomas were arranged in a 1.0-mm tissue microarray (TMA) block. Immunohistochemistry against a large panel of cytokeratins (CK), epidermal growth factor receptor (EGFR), parathyroid hormone-related peptide (PTHrP), syndecan-1, Ki67, p53 and BRAF-V600E were performed. Clinicopathological parameters, including sex, age, tumour size, tumour duration, tumour location, treatment, recurrences, radiographic pattern, vestibular/lingual and basal cortical plates disruption and follow-up data, were obtained from patients' medical records. Immunoexpression of BRAF-V600E was investigated in 73 cases that remained available in TMA sections. Our results indicated that 46.6% (34 cases) demonstrated cytoplasm positivity (six weak and 28 strong positivity). BRAF-V600E expression was associated significantly with the expression of CK8 (P = 0.00077), CK16 (P = 0.05), PTHrP (P = 0.0082) and p53 (P = 0.0087). Additionally, a significant association was seen with the presence of recurrences (P = 0.0008), multilocular radiographic appearance (P = 0.044) and disruption of basal bone cortical (P = 0.05). Univariate analysis showed that BRAF-positive cases (P = 0.001), EGFR-negative/weak positive cases (P = 0.03) and multilocular tumours (P = 0.04) had a significantly lower disease-free survival rate, but these parameters were not considered independent prognostic factors in the multivariate analysis (P > 0.05).

CONCLUSIONS

Our findings suggest an association of BRAF-V600E with parameters of a more aggressive behaviour of ameloblastoma, supporting the future use of BRAF inhibitors for targeted therapy of this neoplasm.

Immunohistochemical biomarkers in ameloblastomas

Ameloblastoma is an aggressive odontogenic tumour, which is locally invasive and highly recurrent. Studies show that ameloblastoma is a benign odontogenic neoplasia, being relatively rare and occasionally presenting behaviour of malignant lesions. In addition to these particularities, the histological diagnosis of ameloblastoma can be challenging when the tumour shows high rates of mitosis, absence of nuclear pleomorphism, basilar hyperplasia and neural invasion. In order to help in the diagnosis, prognosis and treatment of this neoplasia, some immunohistochemical markers were shown to be associated with tumoural epithelium. The identification of these markers as well as of their association with clinical signs can be useful to elaborate more efficient treatment strategies and to control this pathology, including improvement of the quality of life of patients affected by this neoplasia. This article aims to review some markers associated with specific molecular pathways, bone remodelling, cell proliferation, apoptosis, cell signalling and tumour suppression.