BackgroundSolitary fibrous tumour is an unusual neoplasm of the oral cavity that is sometimes not clinically distinguishable from other lesions. The purpose of the present study was to review the clinical, microscopic and molecular aspects of malignant and benign solitary fibrous tumour of the oral cavity currently available in literature.MethodsFor our review, an electronic search was performed using PubMed, Scopus, Ovid/MedLine, Web of science and ProQuest Dissertations and Theses Global database.ResultsA total of 74 publications reporting 150 cases were included. Oral solitary fibrous tumours are most frequently described as submucosal, well‐circumscribed, asymptomatic nodule, more prevalent in females in their fourth to fifth decades of life. Buccal mucosa is the most commonly affected site by the benign tumour variant, whereas the tongue is the most common location affected by the malignant form of the neoplasm. Most of the lesions were treated by conservative surgery. One recurrent malignant tumour and one metastasis are reported.ConclusionAsymptomatic normal‐coloured submucosal nodules located in the buccal mucosa and tongue in adult patients are suggestive of oral solitary fibrous tumour, but only a careful microscopic examination can differentiate benign from malignant variants and the use of immunohistochemistry (CD34, Bcl‐2, CD99 and STAT6), and cytogenetic studies (NAB2‐STAT6) contribute significantly to confirm the diagnosis of solitary fibrous tumour in difficult cases.

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Background: BRAF p.V600E is reported in up to 80% of ameloblastomas. Despite the high frequency, the presence of this mutation in different histopathological areas of the tumour has not been investigated. This information has an important role in the use of BRAF p.V600E assessment as an auxiliary tool in the differential diagnosis between unicystic ameloblastoma and other odontogenic cystic lesions, especially when only incisional biopsies are available. Therefore, the purpose of the present study was to investigate BRAF p.V600E heterogeneity in unicystic ameloblastoma.Methods: Five cases of ameloblastoma and two dentigerous cysts were analysed.The regions exhibiting different microscopic characteristics were selected from each ameloblastoma case and manually dissected. TaqMan allele-specific qPCR or Sanger sequencing was performed to determine BRAF p.V600E status. Results:We screened the mutation in a small cohort of UA and no molecular heterogeneity was found. Four cases of ameloblastoma (80%) exhibited BRAF p.V600E in all different areas evaluated. One case did not harbour the mutation in any microscopic region analysed. The BRAF mutation was absent in the dentigerous cysts. Conclusion:Ameloblastomas appear to exhibit a homogeneous profile regarding the BRAF p.V600E no matter what histological feature is observed under light microscopy, suggesting that this molecular test may contribute to establish the correct diagnosis in cases microscopically resembling other odontogenic lesions.

Background Mitochondrial fission and fusion processes are known as mitochondrial dynamics and the occurrence of imbalances in the mitochondrial activity is related to the pathogenesis of many human cancers. However, the importance of mitochondrial dynamics in malignant salivary gland tumours remains unknown. Therefore, we aimed to investigate its prognostic significance in adenoid cystic carcinoma. Methods Fifty‐seven formalin‐fixed paraffin‐embedded cases were retrieved and disposed in tissue microarray. Histological sections were submitted to immunohistochemical reactions against AMT, DRP1, FIS1, MFN1, MFN2 and OPA1 proteins. Clinical data were retrieved from the patients' medical files, including specific and disease‐free survival data. Results It was observed that 50.9% of the cases were strongly positive for AMT and DRP1, and 49.1%, 21.1%, 22.8% and 24.6% strongly positive for FIS1, MFN1, MFN2 and OPA1, respectively. Reactions were observed in both epithelial and myoepithelial components of the tumour. The higher expression of MFN2 was associated with solid microscopic pattern (p = 0.016). DRP1 overexpression showed a trend towards a shorter overall survival (p = 0.054), while negative/weak OPA1 showed a trend towards a lower disease‐free survival (p = 0.051) in the univariate analysis, but no mitochondrial marker represented an independent prognostic determinant under multivariate analysis. Conclusion In conclusion, mitochondrial dynamics markers do not seem to carry a prognostic significance for adenoid cystic carcinoma patients, but these proteins may play an important role in its pathogenesis.

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Background: This systematic review aimed to investigate the radiological features of lymphomas and leukaemias affecting the jaws.Methods: A systematic literature review was conducted using the electronic databases of PubMed, Web of Science and Scopus. Articles that contained sufficient radiographic examinations (periapical, panoramic or computed tomography images) for individual cases were included. Additionally, either immunohistochemical or molecular confirmation was required prior to inclusion. Three authors evaluated and described the image quality and radiological features.Results: From an initial 1079 articles screened, 129 cases were included, containing 88 tomographic, 76 panoramic and 26 periapical examinations. The quality of the majority of images was sufficient for evaluation. Diffuse large B-cell lymphoma, Burkitt lymphoma, leukemic infiltration, plasmablastic lymphoma and extranodal Natural killer (NK)/T-cell lymphoma, nasal type were the most common subtypes. Involved teeth presented with mobility in 37.2% of the cases and a provisional diagnosis of inflammatory/infectious dental disease was considered in 49.2% of cases. Computed tomography exams were available for 76% of the cases, with most presented with an osteolytic lesion with ill-defined borders. Periosteal reactions were uncommon. Conclusion:Lymphoma/leukaemia infiltrates of the jaw bones are usually of highgrade subtypes and rarely present with periosteal reactions.

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