LAUSR

Langerhans cell histiocytosis (LCH) is a rare condition characterized by proliferation of pathologic Langerhans cells. It is usually diagnosed during the first three decades of life, and has a predilection for males. Even though the pathophysiology of this disorder remains unclarified, it is wellestablished that activating somatic mutations in MAPK pathway genes, particularly BRAFV600E, are present in most cases. MAPK activation in LCH precursor cells drives myeloid differentiation, inhibits migration and apoptosis, resulting in accumulation of abnormal dendritic cells that recruit and activate T-cells. LCH can involve any organ of the human body. However, osseous involvement occurs in approximately two-thirds of patients. The skull, particularly jaw is the most common site of involvement. However, the vertebrae, femur, pelvis, and ribs are also frequently affected locations. Prognosis and treatment for LCH generally depends on the site and size of the lesion, age at presentation, and the presence or absence of multifocal disease. Therapeutic approach includes surgery, radiotherapy, corticosteroids and/or chemotherapy.