Histiocytosis X

Langerhans cell histiocytosis (LCH) is a rare cancer involving clonal proliferation of Langerhans cells, abnormal cells deriving from bone marrow and capable of migrating from skin to lymph nodes. Clinically, its manifestations range from isolated bone lesions to multisystem disease. LCH is part of a group of clinical syndromes called histiocytoses, which are characterized by an abnormal proliferation of histiocytes (an archaic term for activated dendritic cells and macrophages). These diseases are related to other forms of abnormal proliferation of white blood cells, such as leukemias and lymphomas.Histiocytosis X syndromeLetterer-Siwe diseaseHistiocytosis X, unspecifiedEosinophilic GranulomatosisLangerhans Cell granulomatosisLangerhans Cell Histiocytosis, Hashimoto-Pritzker TypeLangerhans Cell Histiocytosis of lungLangerhans Cell Histiocytosis, disseminated (clinical)Langerhans Cell Histiocytosis, unifocal (clinical) Langerhans cell histiocytosis (LCH) is a rare cancer involving clonal proliferation of Langerhans cells, abnormal cells deriving from bone marrow and capable of migrating from skin to lymph nodes. Clinically, its manifestations range from isolated bone lesions to multisystem disease. LCH is part of a group of clinical syndromes called histiocytoses, which are characterized by an abnormal proliferation of histiocytes (an archaic term for activated dendritic cells and macrophages). These diseases are related to other forms of abnormal proliferation of white blood cells, such as leukemias and lymphomas. The cancer has gone by several names, including Hand–Schüller–Christian disease, Abt-Letterer-Siwe disease, Hashimoto-Pritzker disease (a very rare self-limiting variant seen at birth) and histiocytosis X, until it was renamed in 1985 by the Histiocyte Society. The disease spectrum results from clonal accumulation and proliferation of cells resembling the epidermal dendritic cells called Langerhans cells, sometimes called dendritic cell histiocytosis. These cells in combination with lymphocytes, eosinophils, and normal histiocytes form typical LCH lesions that can be found in almost any organ. A similar set of diseases has been described in canine histiocytic diseases. LCH is clinically divided into three groups: unifocal, multifocal unisystem, and multifocal multisystem. Unifocal LCH, also called eosinophilic granuloma (an older term which is now known to be a misnomer), is a slowly progressing disease characterized by an expanding proliferation of Langerhans cells in various bones. It can be a monostotic (involving only one bone) or polyostotic (involving more than one bone) disease. It typically has no extraskeletal involvement, but rarely an identical lesion can be found in the skin, lungs, or stomach. When found in the lungs, it should be distinguished from Pulmonary Langerhans cell hystiocytosis—a special category of disease most commonly seen in adult smokers. This primary bone involvement helps to differentiate eosinophilic granuloma from other forms of Langerhans Cell Histiocytosis (Letterer-Siwe or Hand-Schüller-Christian variant. Seen mostly in children, multifocal unisystem LCH is characterized by fever, bone lesions and diffuse eruptions, usually on the scalp and in the ear canals. 50% of cases involve the pituitary stalk, leading to diabetes insipidus. The triad of diabetes insipidus, exopthalmos, and lytic bone lesions is known as the Hand-Schüller-Christian triad. Peak onset is 2–10 years of age. Multifocal multisystem LCH, also called Letterer-Siwe disease, is a rapidly progressing disease in which Langerhans Cell cells proliferate in many tissues. It is mostly seen in children under age 2, and the prognosis is poor: even with aggressive chemotherapy, the five-year survival is only 50%. Pulmonary Langerhans cell histiocytosis (PLCH) is a unique form of LCH in that it occurs almost exclusively in cigarette smokers. It is now considered a form of smoking-related interstitial lung disease. Some affected people recover completely after they stop smoking, but others develop long-term complications such as pulmonary fibrosis and pulmonary hypertension. PLCH patients, families, and caregivers are encouraged to join the NIH Rare Lung Diseases Consortium Contact Registry. This is a privacy protected site that provides up-to-date information for individuals interested in the latest scientific news, trials, and treatments related to rare lung diseases. LCH provokes a non-specific inflammatory response, which includes fever, lethargy, and weight loss. Organ involvement can also cause more specific symptoms.