“…IHC staining of the histiocytes are positive for S‐100, CD68, and CD163, while CD1a + cells are detected for Langerhans cell histiocytosis. 6 In some forms of RDD, the mutation landscape of MAP2K1 , KRAS , NRAS , and ARAF genes in lesional tissues was also reported. 7 Although a large portion of patients experience spontaneous remission after a few months or years without receiving treatment, the rarity and unpredictability of RDD render a challenging treatment modality.…”