Can BRAF V600E mutation alter F-18 FDG uptake?

Objectives BRAF somatic mutations are found in primary and metastatic melanomas. Commonly found BRAF mutants stimulate RAF/MEK (mitogen-activated ERK-activating kinase)/ERK (extracellular signal-regulated kinase) pathway activation. BRAF V600E is the most common of the BRAF mutations. The objective of this study is to determine if BRAF V600E mutation in melanoma alters F-18 FDG PET/CT uptake in patients with melanoma.

Methods 29 patients with melanoma who had prior PET/CT and subsequent resection were reviewed. However, only 17 patients had enough residual tissue to further evaluation for the BRAF V600E to be included in the study. PET/CT studies were evaluated at the primary and metastatic sites. Pathology was assessed to see the size of the biopsied lesions to ensure that enough of the tissue was present to be localized on the PET/CT scan.

Results BRAF V600E testing was positive in 9 of 17 patients. PET/CT was positive in 5 of 9 patients (55%) and negative on 4 of 9 patients (45%). In patients who had negative BRAF V600E test, PET/CT was positive on 6 of 8 patients (75%) and negative on 2 of 8 patients (25%).

Conclusions A negative PET/CT scan in a patient with a positive BRAF V600E should be scrutinized more carefully as there is a higher probability of a false negative PET/CT scan.