Langerhans Cell Histiocytosis

Langerhans cell histiocytosis (LCH) is a disease characterized by an abnormal clonal proliferation and infiltration of dendritic cells [1–3]. The report on the study of Hand-Schuller-Christian Syndrome, Letterer-Siwe disease, and eosinophilic granuloma was published by Schuller and Christian in 1915–1920. Despite great difference in clinical manifestations, the three diseases show the same microcellular origin under microscope and ultrastructure. LCH may occur at any age, with the peak age of 1–4 years old. The incidence of LCH in children is (2–9)/1,000,000. LCH is more common in male than female, with a male to female ratio of about (1.2–1.4):1. The pathogenesis of LCH remains unknown, and its clinical manifestations are heterogeneous [4–6]. Moreover, it can invade multiple organs and systems of the whole body, even threatening life in severe cases.