Langerhans cell histiocytosis (LCH) is a rare malignant disease with long-term multi-organ and multi-system complications that severely affects the quality of life of patients. More than 40% of LCH patients have BRAF V600E mutation and about 20-25% have MAP2K1 mutation. We report a case of localized Langerhans cell histiocytosis in an adolescent characterized by clonal aggregation of skull Langerhans cells. These Langerhans cells were immunohistochemically positive for CD1a, CD45, CD68, and S100 and were characterized by next-generation sequencing to study BRAF V600E-negative and MAP2K1-positive mutations. The MAP2K1 genomic mutation was identified by NGS to be located in exon 3, including residues E102 and I103.