Background & objectives: BRAF V600K mutation, the second most common mutation in malignant melanoma with a rate of 10-30%, is related to worse response to treatment and adverse prognosis. However, data for comparing V600K/V600E groups for the histopathologic and prognostic features are limited. Methods: A total of 23 malignant melanoma cases with BRAF V600E or BRAF V600K mutations detected by pyrosequencing in our department were retrospectively analysed. The associations between the type of BRAF mutations and histopathologic, clinical and prognostic characteristics were statistically investigated. Results: Of the 23 cases, 7 (30.4%) had V600K and 16 (69.6%) had V600E mutation. Although there was no statistical significance between two groups, most of the cases with V600K mutation were male (85.7%). In BRAF V600K mutant cases, histologic type was mostly superficial spreading melanoma (85.7%), tumour localization was mostly head and neck (57.1%); ulceration and regression were slightly higher. In BRAF V600E mutant group, the number of mitosis (>10/HPF) was higher (81.3%). V600E mutant group was generally more advanced (pT4) at the time of diagnosis (75%). In survival analysis, the estimated survival time was shorter in patients with V600K mutation than those with V600E mutation (17.9 vs 33.2 months). Conclusion: Although it’s a preliminary study and no statistical significance was detected due to the low number of cases, our results emphasize that overall survival time is almost half as short in V600K mutant cases than those with V600E mutation. Considering the prognostic differences, since the double nucleotide change seen in the V600K mutation(GTG to AAG) includes the single nucleotide change seen in the V600E mutation(GTG to GAG), it’s important to be careful in the evaluation to distinguish these two mutations.</p
