Langerhans Cell Histiocytosis in Children and Adults: Similarities and Differences

Abstract

Langerhans cell histiocytosis is an uncommon hematological condition affecting children and adults. It is distinguished by neoplastic infiltration of myeloid dendritic cells and an inflammatory response. Any organ can become dysfunctional as a result of tissue destruction and fibrosis. In almost all cases, activating mutations in the MAPK signal transduction pathway have been found. The earlier these mutations appear during myeloid differentiation, the more severe the disease. The skeleton, skin, and pituitary gland are most typically afflicted in children, but the liver, spleen, and hematopoietic system may also be involved, associated with a worse outcome. In adults, manifestations are most commonly observed in the skeleton, lungs, skin, and in the pituitary region. The course of the disease might range from spontaneous remission to persistent relapse. A histological examination is required to get a definitive diagnosis. In youngsters, where therapeutic surgery and radiation are mostly obsolete, medical therapy is the treatment of choice. Chemotherapy is used when special risk lesions are involved or when children have multifocal skeletal involvement and multisystem disease. In adults, however, local treatments are sufficient in unifocal lesions, and supportive therapy with bisphosphonate is suitable for multifocal bone involvement. Systemic therapy is administered only in patients with multisystem disease and treatment-refractory or quickly reoccurring disease activity. Aside from cytostatics, targeted inhibitors of gene mutations are now accessible for this purpose. While most patients survive, chronic recurrent episodes and late sequelae are the main issues.