Low frequency of BRAF V600E immunoexpression in mandibular ameloblastomas: An institutional study

Ameloblastoma is an uncommon, benign neoplasm of odontogenic epithelium commonly affecting the posterior mandible (almost 80%) particularly in the molar/ramus region, with occasional tumors involving the maxilla. Recently, there has been much interest generated after the reports of BRAF V600E mutations in ameloblastomas with a frequency of 46%-80% using both molecular as well as immunohistochemical (IHC) techniques. We sought to assess the presence of BRAF V600E expression in ameloblastomas in Indian patients and correlate the same with clinical behavior and histological variants by performing IHC analysis with anti-BRAF V600E antibody.

Thirty formalin-fixed paraffin-embedded tissues of mandibular ameloblastomas were examined by anti-BRAF V600E antibody and correlated with clinicopathologic and histological parameters. Cytoplasmic staining of neoplastic epithelium was considered positive for BRAF V600E expression.

Data analysis was performed using Chi-square test and Student's t-test with statistical software IBM SPSS statistics 20.0.

BRAF V600E antibody showed positive expression only in 33.3% (10/30) cases. About 66.7% (4/6) recurrent cases and 63.6% (7/11) plexiform cases showed statistically significant association of P = 0.05 and P = 0.021, respectively, among cases with positive BRAF V600E immunoexpression.

We report the lowest frequency (33.3%) of BRAF V600E immunoexpression in mandibular ameloblastomas in Indian population. However, a significant association of BRAF V600E-positive immunoexpression with recurrence and plexiform pattern could underline its role as a therapeutic marker for ameloblastoma.