Abstract
Langerhans cell histiocytosis (LCH) is characterized genetically by diverse gene mutations of the mitogen-activated protein kinase signaling cascade. BRAFN486_T491delinsK mutation is a rare mutation that involves the β2-αC ring domain, causing activation of the mitogen-activated protein kinase pathway, and is predicted to be resistant to the chemotherapy and BRAFV600E inhibitor in adult LCH cases. Here, we report a childhood LCH case with this novel BRAF mutation and had a good response to conventional chemotherapy. This case report suggests that children with BRAFN486_T491delinsK mutation might differ from adult counterparts in terms of clinical behavior, and conventional chemotherapy might still be an effective therapy.