Outcomes of pediatric LCH patients treated with MAPK pathway inhibitors. (A) [¹⁸F]fluorodeoxyglucose–positron emission tomography scan from patient 17 with disseminated high-risk LCH before (left) and 2 months after (right) treatment with vemurafenib, scored as a partial metabolic response. (B) Magnetic resonance imaging brain (axial T2 fluid-attenuated inversion recovery) from patient 6 with radiologic LCH-ND before (right) and 7 months after (left) treatment with vemurafenib, scored as a partial radiologic response. (C) Graphic representation of progression-free survival (PFS) time (37%) for all patients treated with MAPK inhibition (MAPKi; n = 21). (D) Individual swimmer plots for each patient (n = 21), depicting PFS with MAPKi. Responses for patients (5 and 13) who had both LCH-ND and systemic LCH at start of MAPKi are subdivided as follows: 5.1, swimmer plot for LCH-ND; 5.2, swimmer plot for parietal bone lesion; 13.1, swimmer plot for LCH-ND; 13.2, swimmer plot for LCH liver involvement. BMT, bone marrow transplantation.