The Value of BRAF VE1 Immunoexpression in Pediatric Langerhans Cell Histiocytosis.

VE1 is a monoclonal antibody detecting mutant BRAF V600E protein by immunohistochemistry (IHC) with a high concordance rate with molecular analysis in many cancers. BRAF V600E mutation was assessed on 94 pediatric LCH patients using sequencing analysis and VE1 immunohistochemistry with stringent and lenient-scoring criteria. BRAF V600E mutation exon 15 was detected by sequencing in 47.9% of LCH cases. BRAF V600E mutation rate in multiple-system LCH was 65.2%, significantly higher than in single-system LCH (p = .001). VE1 assays showed 35.6% sensitivity, 75.5% specificity (Stringent criteria), and 91.1% sensitivity, 35.7% specificity (Lenient criteria). The proportion of BRAF V600E mutational status was relatively high and related to high-risk LCH. Molecular assays for BRAF mutation detection are preferred in LCH lesions. VE1 is not ready as an alternative option for LCH BRAF testing.