KRAS and sinus histiocytosis with massive lymphadenopathy: detected BRAF-V600E and KRAS mutations in seven undecalcified primary intraosseous RDD cases, which showed that only one case with the concurrence of RDD and Langerhans cell histiocytosis (LCH) had BRAF-V600E mutation, suggesting that the BRAF-V600E mutation may be caused by LCH lesions rather than RDD lesions.