OBSOLETE: Langerhans cell histiocytosis specific to adulthood

Langerhans cell histiocytosis (LCH) specific to adulthood is a rare histiocytic disorder characterized by the abnormal proliferation and accumulation of Langerhans cells — a type of dendritic cell normally involved in immune surveillance — in various tissues and organs. This Orphanet entry (264750) has been marked as OBSOLETE, meaning it has been retired or merged into broader classifications of Langerhans cell histiocytosis. Adult-onset LCH can affect multiple body systems including the bones, skin, lungs, pituitary gland, liver, lymph nodes, and central nervous system. Common presentations in adults include painful bone lesions (particularly of the skull, ribs, and pelvis), skin rashes, diabetes insipidus due to pituitary involvement, and pulmonary LCH — which is strongly associated with cigarette smoking and presents with cough and dyspnea. Treatment for adult LCH depends on the extent and severity of disease. Single-system disease, such as an isolated bone lesion, may be managed with observation, curettage, or local corticosteroid injection. Multisystem disease typically requires systemic chemotherapy, with agents such as vinblastine and prednisone, or cladribine. Smoking cessation is critical in pulmonary LCH. Targeted therapies, particularly BRAF inhibitors (e.g., vemurafenib) for patients harboring the BRAF V600E mutation, have shown promising results. The prognosis in adults is variable, ranging from spontaneous resolution to chronic relapsing disease or, rarely, life-threatening organ dysfunction. Because this specific Orphanet entry is obsolete, patients and clinicians should refer to the broader Langerhans cell histiocytosis classifications for the most current information.

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