34. Avrupa Patoloji Kongresi , Basel, Switzerland, 3 - 07 September 2022, vol.1, no.481
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.