• Langerhans cell histiocytosis (LCH) is an abnormal clonal proliferation of Langerhans cells, abnormal cells deriving from bone marrow and capable of migrating from skin to lymph nodes. (wikipedia.org)
  • The disease spectrum results from clonal accumulation and proliferation of cells resembling the epidermal dendritic cells called Langerhans cells, sometimes called dendritic cell histiocytosis. (wikipedia.org)
  • Unifocal LCH, also called eosinophilic granuloma (an older term which is now known to be a misnomer), is a disease characterized by an expanding proliferation of Langerhans cells in one organ, where they cause damage called lesions. (wikipedia.org)
  • 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. (wikipedia.org)
  • When found in the skin it is called cutaneous single system Langerhans cell LCH. (wikipedia.org)
  • This primary bone involvement helps to differentiate eosinophilic granuloma from other forms of Langerhans Cell Histiocytosis (Letterer-Siwe or Hand-Schüller-Christian variant). (wikipedia.org)
  • citation needed] Multifocal multisystem LCH, also called Letterer-Siwe disease, is an often rapidly progressing disease in which Langerhans Cell cells proliferate in many tissues. (wikipedia.org)
  • Pulmonary Langerhans cell histiocytosis (PLCH) is a unique form of LCH in that it occurs almost exclusively in cigarette smokers. (wikipedia.org)
  • It is hypothesized that bronchiolar destruction in PLCH is first attributed to the special state of Langerhans cells that induce cytotoxic T-cell responses, and this is further supported by research that has shown an abundance of T-cells in early PLCH lesions that are CD4+ and present early activation markers. (wikipedia.org)
  • Langerhans cell histiocytosis (LCH) is a group of idiopathic disorders characterized by the presence of cells with characteristics similar to bone marrow-derived Langerhans cells juxtaposed against a backdrop of hematopoietic cells, including T-cells, macrophages, and eosinophils. (medscape.com)
  • In 1868, Paul Langerhans discovered the epidermal dendritic cells that now bear his name. (medscape.com)
  • The ultrastructural hallmark of the Langerhans cell, the Birbeck granule, was described a century later. (medscape.com)
  • The term Langerhans cell histiocytosis is generally preferred to the older term, histiocytosis X. This newer name emphasizes the histogenesis of the condition by specifying the type of lesional cell and removes the connotation of the unknown ("X") because its cellular basis has now been clarified. (medscape.com)
  • Although the epidermal Langerhans cell has been presumed to be the cell of origin in LCH, recent studies have called this belief into question. (medscape.com)
  • Specifically, a variety of other cellular populations have been identified that possess phenotypic characteristics similar to Langerhans cells, including expression of CD207 and Birbeck granules. (medscape.com)
  • Therefore, in addition to epidermal Langerhans cells, other potential cellular origins for LCH include dermal langerin + dendritic cells, lymphoid tissue-resident langerin + dendritic cells, and monocytes that can be induced by local environmental stimuli to acquire a Langerhans cell phenotype. (medscape.com)
  • Notably, LCH cells have been found to express markers of both resting epidermal Langerhans cells (CD1a, intracellular major histocompatibility complex II [MHCII], Birbeck granules) and activated Langerhans cells (including CD54 and CD58). (medscape.com)
  • As a result, the pathologic cells of LCH have been hypothesized to represent Langerhans cells in a state of arrested maturation. (medscape.com)
  • [ 3 ] Taken together, these findings have led some to speculate that LCH is not a specific disease of epidermal Langerhans cells, but rather one of mononuclear phagocyte dysregulation. (medscape.com)
  • More recently, histiocytic diseases have been reclassified into five groups: (1) Langerhans-related, (2) cutaneous and mucocutaneous, (3) malignant histiocytosis, (4) Rosai-Dorfman disease, and (5) hemophagocytic lymphohistiocytosis and macrophage activation syndrome. (medscape.com)
  • Broadly speaking, they can be divided into Langerhans and non-Langerhans cell histiocytoses. (thedoctorsdoctor.com)
  • Langerhans cell histiocytoses are all defined by the presence of a unique ultrastructural organelle, the Birbeck granule. (thedoctorsdoctor.com)
  • Currently, the preferred term is Langerhans cell histiocytosis. (thedoctorsdoctor.com)
  • Langerhans cell histiocytosis presenting in the neonatal period: a retrospective case series. (thedoctorsdoctor.com)
  • OBJECTIVES: To describe the morphologic characteristics of skin lesions, extent of extracutaneous disease, and outcomes in patients with neonatal presentation of Langerhans cell histiocytosis (LCH), and to examine clinical predictors of disease prognosis. (thedoctorsdoctor.com)
  • Epidemiologic study of Langerhans cell histiocytosis in children. (thedoctorsdoctor.com)
  • Class IIa dermal dendritic cell histiocytosis is a reactive increase in the number of non-Langerhans' cell histiocytes. (dermnetnz.org)
  • Approximately 50% to 60% of patients with Langerhans cell histiocytosis (LCH) have the BRAF -V600E mutation. (cincinnatichildrens.org)
  • The working group of the Histiocyte Society divided histocytic disorders into three groups: (1) dendritic cell histiocytosis, (2) macrophage-related disorders, and (3) malignant histiocytosis. (medscape.com)
  • Cutaneous histiocytoses are classified according to the type of histiocyte within the skin. (dermnetnz.org)
  • LCH is part of a group of syndromes called histiocytoses, which are characterized by an abnormal proliferation of histiocytes (an archaic term for activated dendritic cells and macrophages). (wikipedia.org)
  • Arguments supporting the reactive nature of LCH include the occurrence of spontaneous remissions, the extensive elaboration of multiple cytokines by dendritic cells and T-cells (the so-called cytokine storm) in LCH lesions, and the good survival rate in patients without organ dysfunction. (medscape.com)
  • These cells in combination with lymphocytes, eosinophils, and normal histiocytes form typical LCH lesions that can be found in almost any organ. (wikipedia.org)
  • citation needed] The disease 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. (wikipedia.org)
  • A histiocytosis is a disease in which there are too many histiocyte cells in the skin and other organs. (dermnetnz.org)
  • Normal histiocyte cells are originally formed within the bone marrow and then migrate throughout the body via the bloodstream. (dermnetnz.org)
  • On the other hand, the infiltration of organs by a monoclonal population of aberrant cells, the possibility of lethal evolution, and the cancer-based modalities of successful treatment are all consistent with a neoplastic process. (medscape.com)
  • It may be possible to tell which type of histiocytosis is present by the appearance of the skin lesion or rash , but a skin biopsy is usually necessary. (dermnetnz.org)
  • Normal histiocyte cells are part of the immune system, alerting infection -fighting cells to the presence of foreign material such as bacteria ( antigen presentation). (dermnetnz.org)
  • 16. High frequency of clonal IG and T-cell receptor gene rearrangements in histiocytic and dendritic cell neoplasms. (nih.gov)
  • Revised classification of histiocytoses and neoplasms of the macrophage-dendritic cell lineages. (medscape.com)
  • LCH is part of a group of syndromes called histiocytoses, which are characterized by an abnormal proliferation of histiocytes (an archaic term for activated dendritic cells and macrophages). (wikipedia.org)
  • BRAF-V600E expression in precursor versus differentiated dendritic cells defines clinically distinct LCH risk groups. (medscape.com)
  • Arguments supporting the reactive nature of LCH include the occurrence of spontaneous remissions, the extensive elaboration of multiple cytokines by dendritic cells and T-cells (the so-called cytokine storm) in LCH lesions, and the good survival rate in patients without organ dysfunction. (medscape.com)
  • These cells carry somatic mutations of BRAF gene and/or NRAS, KRAS , and MAP2K1 genes, which cause activation of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathway. (nih.gov)
  • First-line MAPK inhibition in pediatric histiocytosis: are we ready? (haematologica.org)
  • 7. The histiocytoses: clinical presentation and differential diagnosis. (nih.gov)
  • 9. Epithelioid haemangioendothelioma of the lung imitating clinical features of pulmonary histiocytosis X. (nih.gov)
  • On the other hand, the infiltration of organs by a monoclonal population of aberrant cells, the possibility of lethal evolution, and the cancer-based modalities of successful treatment are all consistent with a neoplastic process. (medscape.com)
  • These diseases are related to other forms of abnormal proliferation of white blood cells, such as leukemias and lymphomas. (wikipedia.org)
  • citation needed] The disease 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. (wikipedia.org)