BRAF and Langerhans cell histiocytosis: BRAF V600E mutations are frequently found in histiocytic/dendritic cell neoplasms such as Erdheim-Chester disease (ECD) and Langerhans cell histiocytosis (LCH), but few reports have also described BRAF mutations in Rosai-Dorfman disease (RDD), and even these cases may predominantly represent mixed histiocytosis.