Unicystic ameloblastoma: a prognostically distinct entity

Unicystic ameloblastoma appeared as a massive multilocular entity: A case report with long-term follow-up

INTRODUCTION

Unicystic ameloblastomas are a rare variant of ameloblastomas, which are characterized by slow growth and being relatively locally aggressive, with the main site of origin being the posterior portion of the mandible, it also refers to those cystic lesions that show clinical, radiographic, or gross features of a jaw cyst.

PRESENTATION OF CASE

A 27-year-old female patient presented with a chief complaint of extensive mass of mandible along with severe swelling and numbness of right lips and chin. The oral examination revealed a swelling in the molar region of the right mandible with buccal plate expansion. The radiographic and histopathologic features were consistent with the diagnosis of unicystic ameloblastoma. Consequently, the lesion was surgically removed, and no clinical or radiological recurrence was detected during 5 years post-operative follow-up.

DISCUSSION

While previous reports of unicystic ameloblastoma in the posterior portion of the jaw showed favorable prognosis lesions appeared as a unilocular entity, this case reports multilocular appearance and aggressive behavior of expansive unicystic ameloblastoma. Furthermore, while some studies linked the unilocular appearance of unicystic ameloblastoma to impacted tooth, our case suggests a possible traumatic link of preexisting lesion into multilocular unicystic ameloblastoma related to impacted tooth.

CONCLUSIONS

This case presents a rare multilocular unicystic ameloblastoma appearance, notably with impacted tooth involvement. It also indicates the potential transformation of solid ameloblastoma into unicystic ameloblastom.

Clinicopathologic Profile and Surgical Modalities in Mandibular Ameloblastoma: A Descriptive Study

BACKGROUND

Ameloblastoma is a benign neoplasm composed of epithelial tissue with invasive and infiltrative behavior at the local level and a high recurrence rate, with various histopathologic patterns and clinical forms. Approximately 85% of conventional ameloblastomas occur in the mandible, most often in the body, angle, and ascending ramus area. The treatment modalities include both conservative and radical treatments. Postoperative follow-up is most important in the treatment of ameloblastoma.

AIMS AND OBJECTIVES

To describe the clinicopathologic profile of mandibular ameloblastoma in patients undergoing different surgical modalities. The primary objective was to describe the clinicopathologic profile and surgical management of mandibular ameloblastoma in patients aged ≥18 years, who had reported to a tertiary dental care center for follow-up during the study period. The secondary objective was to describe the distribution of comorbidities associated with different surgical modalities and reconstructive methods.

SUBJECTS AND METHODS

A total of 34 patients with mandibular ameloblastoma who underwent various surgical modalities between 2011 and 2021 were studied. Information was collected using a predesigned proforma and statistically analyzed.

RESULTS

Thirty-four review cases of ameloblastoma were included in the study. The patients were analyzed concerning age, sex, site, size, clinical presentation, radiographic pattern, histopathologic subtype, type of surgery, and associated comorbidities. Most cases of mandibular ameloblastoma involve the age of 16 to 55 years. The mean age of occurrence was found to be 35.5±13.2. A female preponderance, a tumor size range of 2 to 4 cm, a multicystic variant, involvement of the mandibular body in the premolar-molar area, root resorption, cortical perforation, and a follicular type of histopathologic pattern were the common presentations. Isolated anterior tumors restricted to the incisor/canine region were not found. The common surgical modalities undertaken were conservative methods such as enucleation, and chemical cauterization, and radical methods such as marginal mandibulectomy and segmental resection. Reconstruction using a titanium plate or free fibular graft was performed in the indicated cases. The common comorbidities included difficulty in chewing and loss of facial contour. Recurrence after surgical treatment was rare. Only 9% of cases developed a recurrence within 5 years. No recurrence was noted in cases treated with radical treatment, whereas 50% of cases treated with conservative methods showed recurrence.

CONCLUSION

The age of occurrence, site, and size of the tumor, cortical perforation, root resorption, histopathologic type, and radiographic patterns are widely considered factors in devising a treatment plan for mandibular ameloblastoma. However, there may be rare instances where these tumors behave differently regardless of their innocuous clinicopathologic presentation. Surgical procedures such as segmental resection and marginal mandibulectomy were found to be promising for the eradication of the tumor, and prevention of recurrences and metastasis. However, conservative measures such as enucleation and chemical cauterization were fraught with an increased risk of tumor recurrence and metastasis. Future studies with a larger sample size should focus on the clinicopathologic characteristics of ameloblastoma to elucidate its varied behavior and develop newer and advanced treatment modalities that would provide better surgical and postsurgical outcomes in affected patients.

Ameloblastoma of the Mandible in a 16-Year-Old Female-Case Report

Ameloblastoma is a benign epithelial tumor that has aggressive, destructive and unlimited growth potential, having the capacity for recurrence and malignant transformation. Regarding the symptoms and clinical signs, the presentation of ameloblastoma is poor. In children and young people, 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. The methods of treatment consist of radical surgery (segmental resection) and conservative treatments (enucleation with bone curettage). The particularity of the presented case is represented by the late request for medical consultation, a direct consequence of the measures implemented to prevent and control the spread of COVID-19.

Unicystic Ameloblastoma Associated with Primary Mandibular Second Molar: A Case Report

Background

Unicystic ameloblastoma is a rare, benign, locally invasive odontogenic neoplasm of young age that shows clinical, radiographic, or gross features of an odontogenic cyst but histologically shows typical ameloblastomatous epithelium lining part of the cyst cavity, with or without luminal and/or mural tumor growth.

Aim

To report a case of an asymptomatic unicystic ameloblastoma in a 12-year-old child, along with its management and follow-up.

Case description

A 12-year-old boy presented with swelling with respect to the left body of the mandible. The orthopantomogram (OPG) and computed tomography scan revealed a large unilocular radiolucency in the left mandible associated with the primary second mandibular molar. Complete enucleation of the cyst and extraction of the associated primary teeth and underlying permanent teeth were done under general anesthesia. Carnoy's solution was applied in the bone cavity for 3 minutes with cotton applicators. Postoperative healing was uneventful. Prosthetic rehabilitation was done during the follow-up period.

Conclusion

Unicystic ameloblastoma is rarely seen in younger children, so a pediatric dentist must be cautious while diagnosing an intraoral swelling. Timely intervention and conservative surgical treatment, along with a proper follow-up, improved the treatment outcome and prevented potential complications in the future.

Clinical significance

This report highlights the salient features of unicystic ameloblastoma to be able to accurately diagnose and manage the lesion.

How to cite this article

Peter J, Emmatty TB, Jose B, et al. Unicystic Ameloblastoma Associated with Primary Mandibular Second Molar: A Case Report. Int J Clin Pediatr Dent 2023;16(S-3):S335-S338.

Pediatric Odontogenic Tumors

Odontogenic tumors are rare tumors of the jaws that arise from remnants of the tooth forming apparatus. Some odontogenic tumors demonstrate strong predilection for pediatric patients including the unicystic ameloblastoma, adenomatoid odontogenic tumor, ameloblastic fibroma, ameloblastic fibro-odontoma, odontoma, and primordial odontogenic tumor. In this review, we discuss the clinical, radiographic, histopathologic, and molecular characteristics of select odontogenic tumors that demonstrate pediatric predilection and review management.

Analysis of the 100 most cited articles on ameloblastoma

OBJECTIVES

An increasing number of articles are published each year. The aim of this is to provide a list of the 100 most cited articles on the subject of ameloblastoma.

METHODS

A bibliographic search was performed on Google Scholar (GS), Microsoft Academic (MA), and Dimensions for ameloblastoma. A ranking was created in order of citation density. Graphical representations of keywords and authorship were created with VOSviewer. Statistical analysis was performed and only results with a 95% confidence interval were considered significant.

RESULTS

A helpful list of top 100 articles was developed to help professionals in a variety of ways. Some curiosities are discussed about this scientometric analysis in ameloblastoma articles.

CONCLUSIONS

A useful list of the top 100 most cited articles on ameloblastoma has been provided. Bibliometric and altmetric analysis using Google Scholar, Microsoft Academic, and Dimensions is a free and excellent tool, not only as a citation manager but also as a study reference.

A conservative approach for unicystic ameloblastoma: Retrospective clinic-pathologic analysis of 12 cases

BACKGROUND

Unicystic ameloblastoma is an encapsulated odontogenic neoplasm with a single cyst cavity. The conservative or aggressive surgical approaches used to treat the tumor directly affect recurrence rates. However, there is a lack of a standard protocol that can guide its management.

STUDY DESIGN

We retrospectively reviewed the clinicopathological findings and therapeutical procedures of 12 unicystic ameloblastoma cases treated by the same surgeon during the past 20 years.

METHODS

All cases of unicystic ameloblastoma diagnosed by biopsy and treated by the same surgeon between 2002 and 2022 were reviewed. Eligibility criteria were patients with completely filled-out charts containing the follow-up period and confirmation of the diagnoses based on the microscopic findings of the whole excised specimens. Data collected were categorized into clinical, radiographic, histological, surgical, and recurrence aspects.

RESULTS

There was a female predilection (2:1), and ages ranged between 18 and 61 years (mean: 27.25, ±12.45). Almost all (92%) affected the posterior mandible. Radiographically, the mean length of the lesions was 46.14 mm ± 14.28 mm which 92% were unilocular and 8.3% multilocular. Root resorption (n = 7, 58%), tooth displacement (n = 9, 75%), and cortical perforation (n = 5, 42%) were also observed. The mural histological subtype corresponded to 9 (75%) of the cases. The same conservative protocol was performed in all cases. The follow-up period ranged between 12 and 240 months (~62 ± 65) and recurrence occurred in only one patient (8%).

CONCLUSION

Our findings suggest a conservative approach should be the first option for unicystic ameloblastoma treatment, even for those with mural proliferation.

Diagnostic efficacy of apparent diffusion coefficient, texture features, and their combination for differential diagnosis of odontogenic cysts and tumors

OBJECTIVE

This study assessed the diagnostic efficacy of apparent diffusion coefficient (ADC), texture features, and their combination for the differential diagnosis of odontogenic cysts and tumors with cyst-like features.

STUDY DESIGN

In total, 14 dentigerous cysts (DCs), 12 odontogenic keratocysts (OKCs), and 6 unicystic ameloblastomas (UABs) were used as predictor variables in 32 outpatients who underwent magnetic resonance imaging. The outcome variables were ADC, texture features, and their combination for each lesion. Texture features including histogram and gray-level co-occurrence matrix (GLCM) were measured on ADC maps. Ten features were selected by using the Fisher coefficient method. The Kruskal-Wallis test and post hoc Mann-Whitney test with Bonferroni adjustment were used to analyze trivariate statistics. Statistical significance was established at P < .05. Receiver operating characteristic analysis was used to evaluate the diagnostic effect of ADC, texture features, and their combination in distinguishing the lesions from each other.

RESULTS

Apparent diffusion coefficient, 1 histogram feature, 9 GLCM features, and their combination demonstrated significant differences between DC, OKC, and UAB (P ≤ .01). Receiver operating characteristic analysis revealed a high area under the curve of .95 to 1.00 for ADC, 10 texture features, and their combination. Sensitivity, specificity, and accuracy ranged from .86 to 1.00.

CONCLUSIONS

Apparent diffusion coefficient and texture features, alone or in combination, can be clinically important in facilitating the distinction between these odontogenic lesions.

The Diagnostic Dilemma of an Odontogenic Jaw Lesion in a Pediatric Patient: A Case Report

This paper presents a case report of a 10-year-old child patient reported with the chief complaint of a painless, hard swelling in the lower right back region of the jaw. The clinical and radiographic examination, including intraoral periapical radiograph (IOPA) and cone-beam CT (CBCT), was performed. Conservative treatment was planned based on the clinical and radiological diagnosis of the cyst. But the histological examination revealed unicystic ameloblastoma (UA). This clinical case of UA, which was misdiagnosed as a combination of a radicular cyst and a dentigerous cyst, is being presented to highlight the importance of histopathologic investigation of all tissue specimens retrieved after surgery, particularly when the clinical and radiological findings are insignificant.

A meta-analysis on the presentation of Unicystic Ameloblastoma in the jaws and the consequences for their treatment

INTRODUCTION

This meta-analysis provides reliable data on the prevalence of unicystic ameloblastomas (UA's) among solid/multicystic ameloblastomas (SMA's), as well the ratio of their presence in the maxilla and mandible and in the tooth-bearing area versus the posterior regions of the mandible, including the third molar region and ascending ramus.

MATERIAL AND METHODS

A systematic review and meta-analysis was performed according to PRISMA guideline using the strategy ((unicystic ameloblastoma) OR (((ameloblastoma) OR (solid ameloblastoma)) OR (multicystic ameloblastoma))) NOT ((((systematic review) OR (literature review)) OR (case report)) OR (Immunohistochemical)).

DISCUSSION

The study included 3856 SMA's and 1537 UA's, which amounted to 28.5% UA's. Of the 380 cases of UA from twelve articles that mentioned the involved jaws, 355 were in the mandible and 25 in the maxilla. The preponderance for the mandible is much higher than reports from previous studies of smaller series. Only five articles mentioned the location within the mandible. The vast majority was in the posterior area.

CONCLUSION

The consequences for treatment were discussed, with an emphasis on the approach to unicystic lesions in the posterior part of the mandible for which a protocol is suggested.

Potential role of active decompression and distraction sugosteogenesis for the management of ameloblastomas: Report of two cases and review of the literature

Ameloblastomas are aggressive odontogenic entities well-known for their high tendency to recur. Clinical presentation includes lesions discovered on routine examination or radiographs, pathologies causing facial swelling, pain, cortical expansion, tooth mobility, root resorption, and paresthesia. Radiographic findings comprise large unilocular or multilocular radiolucencies with well-defined borders associated to an impacted tooth. Ameloblastomas are classified as unicystic, multicystic/solid, and peripheral. Treatment options include marsupialization, decompression, enucleation, or curettage with or without adjuvant measures such as Carnoy's solution, marginal resection, and segmental resection. Recently, active decompression with distraction sugosteogenesis (ADDS) was introduced for the conservative management of odontogenic cystic conditions. The purpose of this paper is to present 2 cases of a conventional ameloblastoma treated by means of ADDS. The purpose of this novel approach is to significantly reduce the amount of time required to decompress cystic-like lesions. In these cases, ADDS proved to be a viable treatment because it demonstrated a reduction in size of the initial lesion by new osseous formation within 2 weeks of placement of the device. The cases presented in this paper demonstrate that ADDS could be a valuable treatment modality for this type of ameloblastoma, although further research is necessary to validate this philosophy.

Unicystic ameloblastoma of mural variant crossing the midline

Unicystic ameloblastoma (UCA) refers to cystic lesions that show gross features of a jaw cyst but on histologic examination show a typical ameloblastomatous epithelium lining part of the cyst cavity, with or without luminal and/or mural tumor growth. Even though the lesion is not as aggressive as the solid ameloblastoma, an accurate histopathologic diagnosis is essential for the treatment and prognosis. This case report illustrates a case of UCA of mural variant in the anterior region of the mandible crossing the midline, which is usually an unusual site of occurrence.

Unicystic ameloblastoma: analysis of surgical management and recurrence risk factors

Unicystic ameloblastoma is a distinct pathological variant with varying evidence published about its behaviour and surgical management. Due to a paucity of large studies in the literature with long-term follow up, the aim of this study was to analyse its surgical management and identify clinicopathological features associated with recurrences. All histopathologically confirmed lesions diagnosed at two referral centres between 1995 and 2020 were retrospectively analysed. Demographic, clinical, radiological, and histopathological features were analysed along with surgical methods and follow-up data. Univariate regression analyses were performed to identify risk factors for recurrence. Sixty-three patients were included in the study with mean age of 26.3 years and a male to female ratio of 1:0.75. The majority of lesions occurred in the posterior mandible (57.1%) and were unilocular (88.9%). Most lesions were managed with enucleation followed by application of Carnoy's solution (ferric chloride: 1g; chloroform: 3 mL; glacial acetic acid: 1 mL; ethyl alcohol 96%: 6 mL) and burring of the peripheral bone margin which resulted in the lowest recurrences (9.1%) besides resection. Significantly associated clinicopathological features with recurrences included patients who were male, large lesions (>90 mm), presence of root resorption, cortical perforation, mural subtype, and retention of associated teeth. In conclusion, decision making in the management of unicystic ameloblastoma should be based on the clinicopathological features and not be solely based on the histopathological subtype. Enucleation followed by application of Carnoy's solution and burring of the peripheral bone margin was demonstrated to be the least invasive method with an acceptable low recurrence rate.

Are incisional biopsies reliable for selecting definitive treatment of ameloblastomas? A 15-year interdisciplinary retrospective study

OBJECTIVES

Sampling error in incisional biopsy can lead to under/overtreatment. The aim of this study is to determine the incidence of sampling error/discordance between incisional biopsy and final diagnosis and consequences for treatment outcomes.

STUDY DESIGN

This study is a retrospective cohort study of patients treated for ameloblastoma at an academic medical center from 2005 to 2020. Patients with minimum of 1 year of follow-up after definitive treatment and complete documentation were included. Clinical variables included radiographic findings, incisional biopsy, and final histopathology. Outcome variables were discordance between incisional biopsy and final pathology as well as recurrence rates. Results are primarily descriptive. Fisher's exact test was used to test for differences in recurrence rates.

RESULTS

Twenty-three patients (14 male/9 female) met the inclusion criteria. Overall, discordance was found in 2 cases (8.6%) and sampling error in 3 (13.04%). One of the 3 cases showing sampling error had recurrence and required secondary resection. Six patients (26.1%) had recurrent lesions, and all patients underwent enucleation and curettage with or without peripheral ostectomy.

CONCLUSIONS

Incisional biopsies by themselves are not always consistent with a final diagnosis. Possibility of sampling error should be included in informed consent. Consultation with an oral pathologist is essential at initial and final histopathologic evaluation.

Unicystic Ameloblastoma of Mandible- Imaging Features: A Case Report and Literature Review

Ameloblastoma are benign tumors whose importance lies in its potential to grow into enormous size with resulting bone deformity. They are typically classified as unicystic, multicystic, peripheral, and malignant subtypes. Unicystic ameloblastoma (UA) refers to those cystic lesions that show clinical, radiographic, or gross features of an odontogenic cyst but on histological examination show a typical ameloblastomatous epithelium lining, with or without luminal and/or mural tumor growth. We present a very rare case of unicystic ameloblastoma in a girl child with an age of 10 years; clinical and radiographic features of UCA, its differential diagnosis, histopathology, and current concepts of management have also been discussed in the present paper.

Mandibular unicystic ameloblastoma revealed by florid epulis of the gum: Case report

Ameloblastomas are quite frequent odontogenic tumors, they can be intraosseous or peripheral to the gum, it's rare to find an intraosseous ameloblastoma with gingival extension. Here, we report the case of a 40 years old woman who presented with an exophytic gingival lesion at the gum level of the 46 tooth that was extracted at a quack 01 years before her consultation due to pain in this area. Clinical and radiological examination revealed the presence of two tumors in the same area. The patient benefited from an excision of her gingival tumor and an enucleation of her intraosseous tumor. Histopathological and immunohistochemical examinations revealed that the respective tumors were a spindle cell epulis and an intraluminal unicystic ameloblastoma of different origins, leaving the question and search for the relationship between these two tumors. The postoperative course was uneventful during the 12-month follow-up period after surgical treatment.

Recurrence Rates of Intraosseous Ameloblastoma Cases With Conservative or Aggressive Treatment: A Systematic Review and Meta-Analysis

Objective

This study aimed to systematically investigate and compare the post-treatment recurrence of intraosseous ameloblastoma in patients treated with conservative or aggressive approaches.

Methods

Systemic searches of PubMed, Medline, Cochrane Library, and Embase databases from inception to October 28, 2020, were conducted. Studies that aimed to evaluate the recurrence of intraosseous ameloblastoma by conservative and aggressive treatment approaches were included.

Results

A total of 20 studies with 942 ameloblastoma cases were included. Fourteen studies included patients with ameloblastoma who received conservative treatment, and 16 studies reported the overall recurrence rate for patients undergoing aggressive treatment. The pooled results indicated that the recurrence rate for aggressive treatment [0.12, 95% confidence interval (CI) = 0.09–0.16] was significantly lower than that for conservative treatment, with a recurrence rate of 0.30 (95% CI = 0.23–0.39). Similar results were obtained when stratifying the participants by the histological classification. When trying stratification analysis following the original included studies, multicystic ameloblastoma presented a much higher recurrence rate than solid and unicystic ameloblastomas.

Conclusion

These findings supported the hypothesis that aggressive treatment might lead to a lower recurrence rate than conservative treatment. More studies and meta-analyses following the new histological classification of ameloblastomas are needed to validate and support the findings.

Conceptual changes in ameloblastoma: Suggested re-classification of a "veteran" tumor

OBJECTIVES

The merging of ameloblastoma (AM) with mural unicystic ameloblastoma (UAM-M) was suggested by the 2017 WHO based on similar treatment needs. In an international multicenter study, we investigated the characteristics of their merged product (merged-AM) and raised the possibility of unifying AM and UAM (total-AM).

MATERIALS AND METHODS

AM and UAM (luminal/intraluminal/mural), separate and combined, were analyzed for demographic/clinical/radiological features. ANOVA and chi-square tests were followed by univariate and multivariate analyses, and significance was set at p < .05.

RESULTS

The patients' mean age was 39.6 ± 20.3 years in merged-AM (147 AM, 76 UAM-M), 45.1 ± 19.4 years in AM (p = .009). Merged-AM comprised 51.3% multilocular/48.7% unilocular tumors, AM comprised 72.5%/27.5%, respectively (p < .001). Merged-AM was associated with impacted teeth in 30.8%, AM in 18% (p = .023). The probability of merged-AM for multilocularity increased by 2.4% per year of age (95%CI 0.6-4.2, p = .009). Association with impacted teeth decreased by 7.9% per year of age (95%CI 1.9-14.39, p = .009). Merged-AM did not differ from total-AM (p > .05).

CONCLUSIONS

Merged-AM partially differed from AM, but differences appeared to diminish in an age/time-wise manner. Merged-AM and total-AM were nearly indistinguishable. Therefore, AM and UAM may be considered a continuous spectrum of one type of tumor, further necessitating revision of the treatment approaches.

A Retrospective Study of 158 Cases on the Risk Factors for Recurrence in Ameloblastoma

Background: Ameloblastoma is an odontogenic tumor occurring in jaws, with local aggressiveness and postoperative recurrence. This study was aim to investigate the clinical and radiographic risk factors for recurrence in ameloblastoma. Methods: Patients diagnosed with ameloblastoma between March 2009 and March 2019 were retrospectively analyzed. Clinical and Radiological data and follow-up records were collected. Survival analyses were performed by Kaplan-Meier and log-rank tests, as well as Cox proportional hazards model. Results: One hundred and fifty-eight patients (104 males and 54 females were enrolled. The overall recurrence rate for ameloblastoma was 13.29%, and 10.76% recurred within 5 years. Most of the tumors were located in mandible (86.71%), while the rest 21 cases were in maxilla (13.29%). More than half cases (55.06%) showed multilocular radiolucency, 61 cases (38.61%) showed unilocular radiolucency. Significant differences were found with amelobastoma recurrence rate related to treatment modality, impacted tooth and root resorption (P =0.002, 0.022 and 0.007 respectively). Conclusions: Treatment modality, impacted tooth and root resorption all showed statistically significant associations with the recurrence rate in ameloblastoma. However, due to the limitation of this study, further studies are needed to reveal the true mechanism of ameloblastoma recurrence.

Infected Multilocular Unicystic Ameloblastoma Involving Ramus and Coronoid Process: A Rare Case Report

Ameloblastoma is a neoplasm that originates from the odontogenic epithelium. Unicystic ameloblastoma (UA) is a rare variant of ameloblastoma occurring usually in younger population. They are characterized by slow growth and are locally aggressive, with the main site of origin being the posterior portion of the mandible. Most commonly, UA appears on radiograph as a unilocular well-demarcated radiolucency present mostly in the mandibular posterior region. Here, we report a unique case of multilocular UA in a 22-year-old male patient involving the left side of whole length of the mandibular ramus and coronoid process with impacted third molar.

Ameloblastoma: A succinct review of the classification, genetic understanding and novel molecular targeted therapies

Ameloblastomas are benign but locally invasive neoplasms which may grow to massive proportions and cause significant morbidity. Although some types of ameloblastoma can be treated predictably with aggressive surgical treatment, recurrent ameloblastoma and metastasising ameloblastoma are still difficult to treat. Recent studies have identified recurrent somatic and activating mutations in the mitogen-activated protein kinase (MAPK) and sonic hedgehog (SHH) signalling pathways in ameloblastoma. This development provided a possibility that molecular targeted therapies can be used as neoadjuvant treatment. In this review, we provide a summary of the latest WHO classification of ameloblastoma, the current understanding of genetic mutations and novel molecular targeted therapies arising from the recent developments.

Luminal, Intramural Unicystic Ameloblastoma with Marked Fluid-Fluid Level: Validity of CT and MRI Findings

We report herein a case of a luminal and intramural unicystic ameloblastoma (UA) with a marked fluid-fluid level. The validity of imaging findings in diagnosing UA in the present case is discussed in reference to the literature. The patient was a 50-year-old woman who presented with swelling of the gingiva in the region of the left mandibular third molar and numbness in the lower lip. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a large mass lesion with a unilocular appearance and a biphasic aspect, suggesting liquid content. Contrast-enhanced MRI (CE-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) demonstrated that the biphasic aspect indicated a fluid-fluid level with no blood pooling/flow; it also revealed a thick rim-enhanced margin with mural protrusion. Postoperatively, the lesion was histopathologically diagnosed as a luminal and intramural UA. In conclusion, extensive imaging including both standard CT and MRI together with CE-MRI and DCE-MRI allowed mural protrusions or nodules on a thick cystic wall and liquid content to be correctly identified. This suggests that such imaging can play an important role in diagnosing a UA, even though the results were at first misleading due to the marked fluid-fluid level.

Conservative management is effective in unicystic ameloblastoma occurring from the neonatal period: A case report and a literature review

Unicystic ameloblastoma (UA), a benign odontogenic tumor of the jaw, represents less than a third of all ameloblastomas and seems less aggressive than other types of ameloblastoma. We present here the first case of UA that developed prenatally and was successfully managed in the early neonatal period with marsupialization and curettage performed carefully to avoid injury to the tooth germ. BRAF and SMO mutations were not detected. After 2 years of follow-up, complete reossification and normal eruption of deciduous teeth were noted, and there was no recurrence of UA. We recommend conservative treatment of UA in the pediatric population to avoid loss of and/or injury to the tooth germ, provided close follow-up is carried out all through the individual's growth for early detection of potential recurrences, growth impairments, or tooth eruption disorders. The intratumoral somatic mutational status of BRAF, SMO, RAS family, and FGFR2 may help determine personalized targeted treatment, particularly in case of recurrence.

Adjunctive Strategies for Benign Maxillofacial Pathology

Benign cysts and neoplasms of the maxillofacial region can vary in behavior, with some growing rapidly and resulting in destruction of surrounding structures. Despite their benign histology, many require often-morbid treatment to prevent recurrence of these lesions. Several less invasive and adjunctive medical treatments have been developed to lessen the morbidity of surgical treatment. As the molecular and genomic pathogenesis of these lesions is better understood, more directed treatments may lessen the burden for patients.

Unicystic Ameloblastoma in a Child Treated with a Combination of Conservative Surgery and Orthodontic Treatment: A Case Report

Unicystic ameloblastoma (UAM) is a variant of intraosseous ameloblastoma that occurs as a single cystic cavity. This report describes a case of UAM of the mandible in a seven-year-old girl. The lesion radiographically mimicked a dentigerous cyst. Under the primary diagnosis of a dentigerous cyst, marsupialization was performed to erupt the first molar involved in the cystic lesion and to obtain a definitive diagnosis. The biopsy specimen revealed ameloblastoma. During careful observation, orthodontic treatment, which was performed to upright and promote the eruption of the first molar involved in the tumor, maintained the space needed for enucleation of the tumor. Finally, the second primary molar was extracted, and the lesion was enucleated at 3 years and 4 months after marsupialization. The results of the histological examination revealed UAM. Conclusively, the treatment course not only avoids a resection of the mandible but also induces eruption of the teeth involved in the tumor. Thus, the combination of conservative surgery and orthodontic treatment was effective in the management of UAM that mimics a dentigerous cyst.

Marsupialisation for the treatment of unicystic ameloblastoma of the mandible: a long-term follow up of 116 cases

Unicystic ameloblastoma is a unique histopathological type of ameloblastoma, and treatment is controversial. Marsupialisation is effective in reducing the size of cystic lesions and their complications. We have retrospectively analysed the clinical, histopathological, and prognostic data of affected patients who were treated by marsupialisation between 2003 and 2013 in three Chinese hospitals. Our aim was to evaluate the effects and prognosis, and the factors associated with outcome. A total of 116 patients with mandibular unicystic ameloblastomas were included, and 74, 26, and 16 patients were histopathologically classified as being luminal, intraluminal, and mural subtypes, respectively. Most responded well to marsupialisation, with an overall recurrence rate of 12%. Resorption of the root (p<0.001), perforation of the cortical bone (p=0.005), and histopathological subtype (p=0.013) were the main factors that predicted the outcome. Perforation of the cortical bone was the only reliable predictor of recurrence (p<0.001). Disease-free survival function curves indicated that patients with the mural subtype were at a higher risk of recurrence than patients with the other two subtypes (p=0.003). Poor outcomes of marsupialisation were treated surgically and, to date, no subsequent recurrences have been reported. Marsupialisation is effective for these patients, with a recurrence rate similar to that of radical treatment. The outcomes can be predicted using characteristics of the lesion such as resorption of the root, perforation of the cortical bone, and histopathological subtypes. However, additional studies are required to corroborate these findings.

Conservative Treatment of Ameloblastoma in a Pediatric Patient: A Case Report

Ameloblastomas typically occur in adults and are considered a rarity in the pediatric patient population. We report on the treatment outcome of a pediatric patient who presented with a unicystic ameloblastoma in the mandible. A 15-year-old boy presented with a large, expansile lesion in the ramus-angle region of the mandible. Incisional biopsy findings confirmed the lesion was a type II unicystic ameloblastoma. Treatment consisted of unroofing of the bone overlying the lesion followed by enucleation with peripheral ostectomy. A 10-mL disposable Luer-lock syringe was cut and modified to fit into the window of the lesion to facilitate irrigation with saline solution. The disposable syringe was held in position with 0.18-mm stainless steel wire for 3 months. Modification of the conservative treatment using the syringe allowed for complete regeneration of bone in the large cavity without the need for bone graft or resection of the lesion. At the 3-year follow-up, there was no sign of recurrence.

Ameloblastoma Management: "Horses for Courses" Protocol

Purpose

The purpose of the article is to review 45 cases of ameloblastoma treated in a tertiary care centre depending on the extent of the pathology, in terms of recurrence and morbidity of the patients.

Materials and method

This was a retrospective study of patients who underwent treatment for ameloblastoma between 2009 and 2018 at Vydehi Institute of Dental Sciences, Bangalore. During the first phase of 4 years, the focus of the treatment was on avoiding any recurrence, and therefore, resection followed by reconstruction with reconstruction plates was the only modality used in ten patients. However, from 2014, it was decided to treat each patient based on the extent of the lesion and decide on either conservative management in the form of enucleation followed by peripheral ostectomy and chemical cauterisation or resection with safe margins and reconstruction with reconstruction plates.

Results

The study sample consisted of 45 patients, and the ages ranged from 12 to 65 years with an average of 36. There were 30 males and 15 females. In the first phase of treatment protocol adopted, ten patients underwent resection. In the later period, 18 patients were treated by conservative methods and 16 patients were treated by radical management. There were only three recurrences over a period of 3-year follow-up in the group treated conservatively.

Conclusion

Considering the benign nature of the tumour and the morbidity after resection, patients, most of whom are in the younger age group, can still be subjected to conservative treatment provided they are followed up for a long period thus assuring them of a better quality of life.

Radical vs conservative treatment of intraosseous ameloblastoma: Systematic review and meta-analysis

OBJECTIVES

The aim of the present study was to assess the outcomes of radical and conservative treatment approaches of solid/multicystic and unicystic ameloblastoma in terms of recurrence rates.

MATERIAL AND METHODS

A systematic review and meta-analysis was conducted based on the PRISMA statement. Search was performed using PubMed, Embase, SCOPUS, and Web of Science for articles published from January 1969 until March 2018. Quality assessment of the selected articles was conducted using the Quality Appraisal of Case Series Studies Checklist. The meta-analysis was performed using the MedCalc program.

RESULTS

The search strategy yielded 6,984 articles; 20 studies met the eligibility criteria and were included in the meta-analysis. The pooled recurrence rate of solid/multicystic ameloblastomas following radical treatment was 8%, while conservative treatment caused recurrences in 41%. For unicystic ameloblastomas, these values were 3% and 21%, respectively. The risk of recurrences in both types of ameloblastomas following radical treatment was lower than following conservative treatment.

CONCLUSIONS

The present study showed statistically significant differences in recurrence favoring radical treatment for both unicystic and solid/multicystic ameloblastoma. The solid/multicystic type showed more recurrences than the unicystic type. Unfortunately, since only retrospective studies were available, the evidence is less strong as wished for.

The Mutational Profile of Unicystic Ameloblastoma

BRAF V600E is the most common mutation in conventional ameloblastoma (AM) of the mandible. In contrast, maxillary AMs appear to harbor more frequently RAS, FGFR2, or SMO mutations. Unicystic ameloblastoma (UAM) is considered a less aggressive variant of ameloblastoma, amenable to more conservative treatment, and classified as a distinct entity. The aim of this study was to characterize the mutation profile of UAM ( n = 39) and to compare it to conventional AM ( n = 39). The associations between mutation status and recurrence probability were also analyzed. In the mandible, 94% of UAMs (29/31, including 8/8 luminal, 6/8 intraluminal, and 15/15 mural subtypes) and 74% of AMs (28/38) revealed BRAF V600E mutations. Among the BRAF wild-type cases, 1 UAM showed a missense SMO mutation (p.L412F), whereas 2 NRAS (p.Q61R), 2 HRAS (p.Q61R), and 2 FGFR2 (p.C383R) activating mutations were identified in AM. Of the 3 maxillary UAMs, only 1 revealed a BRAF V600E mutation. Taken together, our findings demonstrate high frequency of activating BRAF V600E mutations in both UAM and AM of the mandible. In maxillary UAMs, the BRAF V600E mutation prevalence appears to be lower as was shown for AM previously. It could therefore be argued that UAM and AM are part of the spectrum of the same disease. AMs without BRAF V600E mutations were associated with an increased rate of local recurrence ( P = 0.0003), which might indicate that routine mutation testing also has an impact on prognosis.

Marsupialization of mandibular cystic ameloblastoma: Retrospective study of 7 years

BACKGROUND

This retrospective study investigated the reduction rate and speed of shrinkage after marsupialization in mandibular cystic ameloblastoma and clarified whether marsupialization is appropriate for unicystic ameloblastoma and multicystic ameloblastoma.

METHODS

Sixty-three patients with mandibular cystic ameloblastoma were initially treated with marsupialization. Premarsupialization and postmarsupialization panoramic radiographs were reviewed for reduction rate and speed of shrinkage, and then were evaluated with age, sex, tumor location, and tumor type.

RESULTS

The overall recurrence rate was 4.5% (2/44). The average reduction rate after marsupialization was 65.6%. No significant difference was found between unicystic ameloblastoma and multicystic ameloblastoma in reduction rate. The speed of shrinkage of unicystic ameloblastoma was significantly faster than that of multicystic ameloblastoma (P < .05). Similarly, patients with multicystic ameloblastoma had longer marsupialization periods than those with unicystic ameloblastoma (P < .05).

CONCLUSION

Marsupialization is effective in reducing tumor size for both unicystic ameloblastoma and multicystic ameloblastoma. Marsupialization plus second-stage curettage is recommended as the primary treatment for mandibular cystic ameloblastoma.

3D cone beam computed tomography reconstruction images in diagnosis of ameloblastomas of lower jaw: A case report and mini review

Cone beam computed tomography (CBCT) has obvious advantages over regular radiography in diagnosis of complex diseases. Objective of this study is to report a case of a mandibular jaw ameloblastoma recurring cyst, which represents a benign tumor of odontogenic epithelium, using CBCT imaging technology. CBCT examination of the patient suffering with recurrent lower jaw cyst (relapsing four years after surgery) showed a decrease in irregular bone density and appearance of a honeycomb pattern (3.5 cm×2.5 cm×1.8 cm) in the right lower jaw. This suggests that the lesion is more likely to be an ameloblastoma. Preoperative tissue biopsy and pathological examination of surgical sample confirmed the diagnosis. Surgical resection of the diseased tissue and autogenous bone grafting in the mandible was performed. Postoperative CBCT examination showed that the bone defect healed well, without recurrence of the tumor 22 months postoperatively. In conclusion, the rotated 3D CBCT images clearly displays the exact size, location, borders and internal changes of the tumor in the jaw cyst itself and the adjacent tissues. Thus, the dental CBCT allows clinicians to better evaluate lesions, leading to better treatment outcomes.

Unicystic ameloblastoma in conjunction with peripheral ameloblastoma: A unique case report presenting with diverse histological patterns

Ameloblastomas are benign epithelial odontogenic neoplasms which are locally aggressive with an insidious growth pattern. Based on the clinical, radiographic, histopathology and behavioral and prognostic aspects, four variants of ameloblastoma are distinguished. They include solid/multicystic ameloblastoma, unicystic ameloblastoma (UA), peripheral ameloblastoma (PA) and desmoplastic ameloblastoma. UA and PA are two variants that have no clinical or radiological resemblance to each other. A case of simultaneous occurrence of these two lesions displaying an array of different histopathological entities together, with a note on pathological insight, has been reported in a 59-year-old adult male patient.

Maxillary ameloblastoma: Factors associated with risk of recurrence

BACKGROUND

Maxillary ameloblastomas are rare and associated with an aggressive course because of the anatomic composition of the maxilla and adjacent structures. The risk factors associated with recurrence were analyzed in this retrospective study.

METHODS

Cases of maxillary ameloblastoma reported in a tertiary hospital from 2005 to 2015 were analyzed to identify clinicopathological and radiological factors associated with recurrence using univariate and multivariate Cox regression analyses.

RESULTS

A total of 890 patients with ameloblastomas were treated in this study, of whom only 51 (5.7%) had maxillary ameloblastomas. The median follow-up period was 56 ± 28.65 months. Of the maxillary ameloblastomas, 29 (56.8%) were primary and 22 (43.1%) were recurrent. Soft tissue or maxillary sinus invasion and primary or recurrent tumor status were risk factors significantly associated with recurrence in the univariate analyses (p = .006 vs p = .025, respectively), whereas the association between recurrence and surgical methods was borderline significant (p = .08). The multivariate Cox regression analysis showed that soft tissue or maxillary sinus involvement was significantly associated with recurrence (p = .023).

CONCLUSION

Recurrent tumors and tumors with soft tissue or maxillary sinus involvement were risk factors for recurrence among patients with maxillary ameloblastoma. © 2017 Wiley Periodicals, Inc. Head Neck 39: 996-1000, 2017.

Update from the 4th Edition of the World Health Organization Classification of Head and Neck Tumours: Odontogenic and Maxillofacial Bone Tumors

The 4th edition of the World Health Organization's Classification of Head and Neck Tumours was published in January of 2017. This article provides a summary of the changes to Chapter 4 Tumours of the oral cavity and mobile tongue and Chapter 8 Odontogenic and maxillofacial bone tumours. Odontogenic cysts which were eliminated from the 3rd 2005 edition were included in the 4th edition as well as other unique allied conditons of the jaws. Many new tumors published since 2005 have been included in the 2017 classification.

Unicystic Ameloblastoma: Rehabilitation with Chin Graft Harvested and Implant-Supported Fixed Prosthesis

Objective

The objective is to present a clinical case of a 38-year-old male with a maxillary unicystic ameloblastoma treated by means of tumor block resection followed by chin-harvested graft placement in order to place two dental implants for esthetic and functional rehabilitation.

Methods

Ameloblastoma is a benign odontogenic tumor characterized by local aggression and a high rate of recurrence; the latter partly depends on how it is treated. Complete resection of the tumor, which usually prevents recurrence, produces bone defects of varying size that must be reconstructed later on. In most cases this is done using bone grafts and implant-supported prostheses. Grafts harvested from the chin are relatively easy to obtain and enjoy a fairly uneventful post-operative with few complications; they are suitable for cases in which the defect generated by resection is of small size.

Results

Functional and esthetic rehabilitation and the tumor has not relapsed during a 7-year follow-up.

Conclusion

Tumor block resection followed by chin-harvested graft placement and dental implants is a safe treatment for patients with unicystic ameloblastoma.

What Is Important for Confirming Negative Margins When Resecting Mandibular Ameloblastomas?

PURPOSE

The purpose of this study was to assess the utility of intraoperative radiographs and frozen sections in achieving negative margins and preventing recurrence of mandibular ameloblastomas.

MATERIALS AND METHODS

This was a retrospective cohort study of patients who underwent resection (≥1 cm) of mandibular ameloblastomas from 2005 through 2015. Patients were included if they had at least 1-year follow-up and complete records. Demographic variables included age, gender, and type of resection (segmental vs marginal). Predictor variables were type of margin assessment: 1) frozen section, 2) intraoperative ex vivo specimen radiograph, 3) both, or 4) none. The outcome variables were final margin status and recurrence rate. Accuracy of intraoperative radiographic margins was determined by comparison with histologic margin distance. Descriptive statistics were conducted with the Fisher exact test.

RESULTS

The study sample consisted of 35 patients (47.5 ± 20.4 yr old; 16 men) who underwent 25 segmental and 10 marginal resections. Ten had frozen sections only, 3 had ex vivo specimen radiographs only, 10 had no intraoperative measurements, and 12 had both. There were no positive frozen sections. One patient had a positive posterior bony margin at final pathology despite negative frozen section histology. There was no difference in recurrence rate at latest follow-up among cohorts. The anterior radiographic margin was 11.8 ± 5.9 mm compared with 11.5 ± 7.5 mm by histology (P = .124). The posterior radiographic margin was 12.3 ± 5.3 mm compared with 9.8 ± 6.5 mm histologically (P = .546). Margin distances that were at least 5 mm when measured with specimen radiographs had histologic margin distances of at least 5 mm in 25 of 30 resection margins (83.3%).

CONCLUSION

Resection of ameloblastoma with planned margins of at least 1 cm is sufficient to prevent recurrence of ameloblastoma. Achieving a radiographic margin of at least 5 mm provided a histologic margin of at least 5 mm 83.3% of the time.

A Conservative Approach to a Peripheral Ameloblastoma

Peripheral Ameloblastoma (PA) is the rarest variant of ameloblastoma. It differs from the other subtypes of ameloblastoma in its localization: it arises in the soft tissues of the oral cavity coating the tooth bearing bones. Generally, it manifests nonaggressive behavior and it can be treated with complete removal by local conservative excision. In this study we report a case of PA of the maxilla in a 78-year-old female patient and we describe the four different histopathological patterns revealed by histological examination. After local excision and diagnosis, we planned a long term follow-up: in one year no recurrence had been reported. The choice of treatment is illustrated in Discussion.

"Evaluation of safety margin" in ameloblastoma of the mandible by surgical, radiological, and histopathological methods: An evidence-based study

OBJECTIVE

The purpose of this study is to elicit the amount of safety margin necessary around the ameloblastic lesion in view of preventing further recurrence.

MATERIALS AND METHODS

The study consisted of 25 cases of mandibular ameloblastoma. Diagnosis was based on clinical and radiological analysis and confirmed by histopathological report. An incisional biopsy was done preoperatively to confirm the diagnosis. Segmental resection was planned for all the cases. After the resection, postoperative panoramic radiograph of the specimen was taken followed by histopathological examination of its margin to detect tumor cell infiltration.

RESULTS AND CONCLUSION

In all our cases, the ameloblastoma was infiltrating in nature. A follow-up period of 10 years showed neither recurrence nor implant failure. In our study, we conclude our safe margin for infiltrating variant of ameloblastoma based on histopathological report of the resected specimen.

Maxillary unicystic ameloblastoma: a case report

Background

Ameloblastoma is a benign epithelial odontogenic tumor. It is often aggressive and destructive, with the capacity to attain great size, erode bone and invade adjacent structures. Unicystic ameloblastoma is a rare odontogenic lesion, with clinical, radiographic and gross features of jaw cysts. The lesion histologically shows typical ameloblastomatous epithelium lining part of the cyst cavity with or without and/or mural tumor growth. Unicystic ameloblastoma usually presents in posterior mandibular ramus region, while it is rare and atypical in posterior maxillary region. .

Case presentation

We report a case of 16 year old Kosovar male, Albanian ethnicity, who presented with a swelling located in right maxillary region. Clinical examination revealed a painless swelling extending from the maxillary right central incisor to the maxillary right first molar tooth. Panoramic radiograph disclosed a well corticated unilocular radiolucent lesion approximately 5 × 5 cm in diameter which was in contact with the roots of the teeth present inferiorly and with the maxillary sinus superiorly. Maxillary right canine impaction was noted and unerupted lateral incisor tooth was present inside the radiolucency. Preoperative diagnosis of the lesion was made as dentigerous cyst based on the age of the patient, location of the swelling, clinical and radiographic findings, but the unicystic ameloblastoma was also taken into consideration. The patient was treated by surgical enucleation of the lesion and extraction of lateral incisor tooth which was present inside the lesion. The histopathological examination of the lesion revealed confirmed finding for unicystic ameloblastoma mural form. No recurrence was observed in 1 year follow-up.

Conclusions

Maxillary region is considered a rare and atypical location for unicystic ameloblastoma. We emphasize the importance of differential diagnosis of an odontogenic lesion with common clinical and radiological features that will impact the treatment planning and follow up. As oral health providers we should be aware that the unilocular radiolucencies may be unicystic ameloblastoma.

Dentigerous Cyst and Ameloblastoma of the Jaws

AIM

To determine how many ameloblastomas were misdiagnosed as dentigerous cysts (DCs) by correlating the radiological and histopathological features of a series of both entities.

METHODS AND RESULTS

Histopathology reports and radiological imaging of 135 DCs and 43 ameloblastomas were reviewed. Any clinical or radiological feature that suggested that the diagnosis of DC was wrong-for example, absence of an unerupted tooth-prompted review of the original histology. A total of 34 cases coded as DC at diagnosis were excluded; in the remaining 101 patients, the clinicoradiological and histopathological features were consistent with DC in 96 (95.0%). Review of the histology revealed that 4 patients had actually had odontogenic keratocysts (OKCs) and one a luminal/simple unicystic ameloblastoma (UA). One other OKC and 3 other ameloblastomas (1 luminal UA, 2 solid/multicystic) had originally been diagnosed as DC; these had been identified prior to the study. Of the 9 misdiagnosed patients, 6 were ≤20 years old. Clinically, DC had been the only, or one of the differential, diagnoses in 7 patients; in the other 2, the clinical diagnosis was radicular cyst. In none of the 4 misdiagnosed ameloblastomas was the radiology compatible with a diagnosis of DC. Incorrect terminology had been used on the histopathology request form in 5 of the 34 excluded cases where the clinical diagnosis was DC, despite the cyst being periapical to an erupted carious or root-filled tooth.

CONCLUSIONS

The entire clinical team must ensure that a histopathological diagnosis of DC is consistent with the clinicoradiological scenario, particularly in younger patients.

Odontogenic Cysts and Tumors

This article presents various odontogenic cysts and tumors, including periapical cysts, dentigerous cysts, odontogenic keratocysts, orthokeratinized odontogenic cysts, lateral periodontal cysts, glandular odontogenic cysts, ameloblastomas, clear cell odontogenic carcinomas, adenomatoid odontogenic tumors, calcifying epithelial odontogenic tumors, squamous odontogenic tumors, ameloblastic fibromas, ameloblastic fibro-odontomas, odontomas, calcifying cystic odontogenic tumors, and odontogenic myxomas. The authors provide an overview of these cysts and tumors, with microsopic features, gross features, differential diagnosis, prognosis, and potential diagnostic pitfalls.