Immunohistochemical analysis of BRAF V600E mutation in ameloblastomas.

OBJECTIVE: This study aimed to investigate the presence of BRAF V600E mutation in mandible ameloblastomas by correlating clinical and imaging data on the cases studied. METHODS: Eighty-four cases diagnosed as mandibular ameloblastoma were selected for analysis. The specimens were submitted to immunohistochemistry for detection of BRAF V600E mutated protein. Clinical-pathological data such as age, gender, tumour size, mandibular location, radiographic aspects, histological type and sub-type, and tumour status were collected. The clinical-pathological parameters were categorised and analysed according to BRAF V600E detection. RESULTS: Of the 84 patients, 78.6% (66 cases) demonstrated positivity for anti-BRAF V600E antibody, whereas 18 were negative (21.4%). The correlation between BRAF expression and variables showed statistical significances for mandibular location (P = 0.0353) and tumour size (P = 0.008), whereas no statistical significance was observed for gender, age, radiographic aspect, histological pattern, histological sub-type and tumour status. Multivariate logistic regression revealed a significant risk for BRAF positivity in tumours with posterior mandibular location (OR = 7.23, P = 0.0451) and size > 4 cm (OR = 7.29, P = 0.0150). CONCLUSION: BRAF V600E mutation is common in mandibular ameloblastomas, especially in cases of tumours larger than 4 cm and in the posterior region of the mandible. In addition, this mutation can occur regardless of histological type of the tumour, age, gender, radiographic aspect and tumour status. CLINICAL SIGNIFICANCE: The association between clinical-pathologic features and BRAF V600E mutation in ameloblastomas may provide directions for the treatment of this neoplasia. The use of BRAF inhibitors for targeted therapy could lead to an establishment of an alternative compared to the resective surgery.