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Query: UMLS:C0019621 (Langerhans cell histiocytosis)
 3,250 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The histiocytoses, whether reactive or neoplastic, can be related histologically and immunophenotypically to their normal counterparts within the histiocytic system. This system has two subsets: The dendritic (antigen-presenting) cells and the phagocytic histiocytic (antigen-processing) cells. Dermatopathic lymphadenitis and Langerhans cell histiocytosis (histiocytosis X) are reactive proliferative disorders of dendritic cells. Malignancies of dendritic cells exist, but they are very rare. Benign proliferations of phagocytic histiocytes include the hemophagocytic syndromes, both familial and reactive, as well as sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease) and histiocytic necrotizing lymphadenitis (Kikuchi's disease). Neoplasms of phagocytic histiocytes include acute monocytic leukemia and the very rare entities, malignant histiocytosis and true histiocytic lymphoma. The latter must be distinguished from sinusoidal, large cell anaplastic lymphomas.
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PMID:The histiocytoses: clinical presentation and differential diagnosis. 215 Mar 25

The term histiocyte refers to cells of either the macrophage or Langerhans cell lineages. The histiocytic disorders are characterized by the proliferation of cells of these lineages. With recent advances in knowledge of the developmental biology of histiocytic cells, it is now possible to formulate a reasonable catalogue of histiocytic diseases based on ultra-structural and phenotypic markers of cellular origins and molecular or chromosomal markers of malignancy. The catalogue includes the following groups of diseases. Nonmalignant reactive macrophage disorders include (1) macrophage storage diseases, (2) several benign proliferative macrophage disorders that predominantly involve skin and bone, and (3) several hemophagocytic syndromes that vary from indolent and benign to fulminant and fatal. In some of the latter disorders, viruses have been identified as the inciting stimulus. The malignant macrophage disorders include (1) acute monocytic leukemia and (2) chronic myelomonocytic leukemia. A rare disorder that gave rise to a permanent cell line with an anomaly of chromosomal segment 5q35 may also be an example of a histiocytic malignancy. The existence of a separate category of true histiocytic lymphoma of macrophage type is uncertain. Reactive Langerhans cell disorders include (1) congenital self-healing histiocytosis, (2) the many variants of eosinophilic granuloma, and (3) a related disorder designated as relapsing Langerhans cell histiocytosis that is characterized by a relapsing course and infiltration of bone and soft tissues by Langerhans cells. Presumptively neoplastic diseases of Langerhans and dendritic cells include (1) progressive Langerhans cell histiocytosis, a disease with prominent involvement of blood and BM as well as skin and viscera; (2) Langerhans cell lymphoma, and (3) dendritic cell lymphoma. However, clonality as a marker of malignancy has not been proven in these disorders.
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PMID:Histiocytes and histiocytosis. 771 2

Retrospective analysis of childhood histiocytoses treated at the Department of Pediatrics, Ramathibodi Hospital from May 1970 till June 30, 1992 to verify the prevalence according to the recent classification, course and prognosis was conducted. Among 120 cases, 54 were Class I or Langerhan Cell Histiocytosis (LCH, previously called Histiocytosis-X). Nineteen cases were Class II: Infection-Associated Hemophagocytic Syndrome (IAHS) and Sinus Histiocytosis. Forty-seven cases were class III which included acute monocytic leukemia, juvenile CML; malignant histiocytosis, HMR, and histiocytic lymphoma. Excellent prognosis (cure) was seen in all cases of Hand-Schuller Christian Disease, eosinophilic granuloma, sinus histiocytosis with massive lymphadenopathy and many cases of Class II (except IAHS). The worse prognosis (100% mortality rate) was seen in HMR and juvenile CML. The intermediate prognosis (50%, 54%, 58.8% and 66.7% mortality rate) was seen in MH, HL, LSD and IAHS respectively. To differentiate between IAHS and MH/HMR, the prominent bone marrow findings in 12 cases of IAHS revealed that every case showed prominent hemophagocytosis by the promono-histiocytes/histiocytes, the maximal total erythroblasts (TE) were only 7.5 per cent except for 3 cases; in which one case with agranulocytosis from co-trimoxazole had 84 per cent erythroid cells, one case with prior co-trimoxazole treatment had 37 per cent TE, the last one had 40 per cent TE with massive GI bleeding while in the recovery stage of DHF. All 5 cases of HMR had prominent hemophagocytosis and increased TE (> 22%).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Histiocytoses in children: analysis of 120 cases and the bone marrow findings in infection-induced hemophagocytic syndrome vs malignant histiocytosis. 782 9