Although no studies have demonstrated an association between this mutation and specific clinical risk groups, it has been associated with an increased risk of recurrence.26–28 Moreover, this mutation has also been reported in immune cell subsets in the tumor microenvironment, such as circulating CD11C and CD14-positive cells and CD34-positive bone marrow hematopoietic progenitor cells, in LCH patients with active and high risk.29 However, reports on the correlation between the BRAF V600E mutation in LCH and the development or progression of inflammation remain lacking. This evidence concerns the gene CD34 and Langerhans cell histiocytosis.