Thelansis

 Langerhans cell histiocytosis (LCH) is a disease caused by the clonal expansion of myeloid precursors that differentiate into CD1a+/CD207+ cells in lesions, resulting in organ involvement and dysfunction. To diagnose LCH, there must be a clonal neoplastic proliferation expressing CD1a, CD207 (Langerin), and S100. The causes and risk factors for developing LCH are currently unknown. The classification system is based on the site of the lesions, the number of involved sites, and whether the disease involves risk organs such as the hematopoietic system, liver, or spleen. There are five groups of histiocytic disorders, including LCH-related, cutaneous and mucocutaneous non-LCH histiocytoses, Rosai-Dorfman disease, malignant histiocytoses, and hemophagocytic lymphohistiocytosis and macrophage activation syndrome. LCH commonly affects the skeletal system, with bone lesions in approximately 80% of patients. Half of these patients have single lesions, and the skull is the most common site...