Molecular and immunohistochemical analysis of BRAF gene in primary cutaneous melanoma: Discovery of novel mutations

Abstract

Background: Determination of BRAF status is mandatory for targeted therapy but it is not currently available in most developing countries.

Aim: We aimed to analyze BRAF mutations in a series of cutaneous melanoma of Tunisian patients and to compare BRAF V600E mutation detection by immunohistochemistry to DNA sequencing.

Patients and methods: Archival formalin fixed paraffin embedded tissues from 28 patients with primary cutaneous melanoma were evaluated for the BRAF mutations by Sanger sequencing and immunohistochemistry.

Results: BRAF mutations were detected in 19/28 (68%) of analyzed tumors. The sensitivity and specificity of immunohistochemistry compared to DNA sequencing for identification of the BRAF V600E mutation were 100%. We found five novel mutations, one of them had deleterious effect.

Conclusion: The present study shows an intermediate frequency of mutations of the BRAF gene in cutaneous melanoma of Tunisian patients, and supports the use of immunohistochemistry as a screening test for the assessment of the BRAF V600E status in the management of melanoma in clinical practice.

Keywords: BRAF mutations; V600E; cutaneous melanoma; immunohistochemistry; sequencing.