| histiocytoma | <tumour> A tumour composed of histiocytes. Origin: histio-+ G. Kytos, cell, + -oma, tumour (05 Mar 2000) |
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| histiocytoma, fibrous | A tumour composed, wholly or in part, of cells with the morphologic characteristics of histiocytes and with various fibroblastic components. There are many variants and many names. Superficially located histiocytic lesions behave benignly but deep, benign histiocytomas may invade locally into surrounding tissue. Fibrous histiocytomas can occur anywhere in the body. Superficial lesions are always cured by simple excision; a wider margin of tissue should be obtained for deep, benign types. Local recurrence is uncommon. (12 Dec 1998) |
| histiocytosis | A condition marked by the abnormal appearance of histiocytes (macrophages) in the blood. Lipid h., Niemann-Pick disease. Sinus h., a disorder of the lymph nodes in which the distended sinuses are completely or nearly completely, filled by histiocytes, as a result of active multiplication of the littoral cells. H. X, a generic term embracing eosinophilic granuloma, Letterer-Siwe disease and Hand-Schuller-Christian disease and indicating a shared common origin for the three entities. (16 Dec 1997) |
| histiocytosis x | An immunologic disorder of unknown cause where there is proliferation of histiocytes (a type of cell in the immune system) in the bloodstream. The disorder is characterised by inflammation of the bronchioles and small pulmonary vessels that leads to fibrosis and destruction of alveolar cell walls. Cigarette smoking is considered a risk factor. Individuals with this disorder are also at increased risk for spontaneous pneumothorax. Symptoms include cough, chest pains, shortness of breath, fever, weight loss and malaise. Bronchoscopy with biopsy confirms the diagnosis. Childhood forms exist and cause more systemic symptoms and findings such as failure to thrive, weight loss, fevers, irritability, rash and bone pains. Treatment is with corticosteroids. (27 Sep 1997) |
| histiocytosis Y | A papilloma of the oral mucosa and skin in which squamous epithelium covers connective tissue papillae filled with large foamy histiocytes. Synonym: histiocytosis Y. (05 Mar 2000) |
| histiocytosis, langerhans-cell | Group of disorders of histiocyte proliferation which includes letterer-siwe disease, hand-schueller-christian syndrome, and eosinophilic granuloma. Langerhans cells are components of the lesions. (12 Dec 1998) |
| histiocytosis, malignant | A rare, usually rapidly progressive disorder, characterised by abrupt onset, fever, weight loss, hepato-splenomegaly, pancytopenia, and lymphadenopathy. (12 Dec 1998) |
| histiocytosis, non-langerhans-cell | Group of disorders which feature accumulations of active histiocytes and lymphocytes, but where the histiocytes are not langerhans cells. The group includes haemophagocytic lymphohistiocytosis, infection-associated haemophagocytic syndrome, sinus histiocytosis, xanthogranuloma, reticulohistiocytoma, juvenile xanthoma, xanthoma disseminatum, as well as the lipid storage diseases (sea-blue histiocyte syndrome and niemann-pick disease). (12 Dec 1998) |
| histiocytosis, sinus | Benign, non-langerhans-cell, histiocytic proliferative disorder that primarily affects the lymph nodes. It is often referred to as sinus histiocytosis with massive lymphadenopathy. (12 Dec 1998) |
| histiogenic | Formed by the tissues; e.g., the histogenous cells in an exudate arising from proliferation of the fixed tissue cells. Synonym: histiogenic. Origin: histo-+ G. -gen, producing (05 Mar 2000) |
| histioid | 1. Resembling in structure one of the tissues of the body. 2. Sometimes used with reference to the histologic structure of a neoplasm derived from and consisting of a single, relatively simple type of neoplastic tissue that closely resembles the normal, as in certain fibromas and leiomyomas. Synonym: histioid. Origin: histo-+ G. Eidos, resemblance (05 Mar 2000) |
| histiology | <study> Same as Histology. Origin: Gr. "istos tissue. Source: Websters Dictionary (01 Mar 1998) |
| histioma | <oncology, tumour> A histoma is any tumour which was derived from mature tissue. (09 Oct 1997) |
| histionic | Relating to any tissue. (05 Mar 2000) |
| histo- | Tissue. Origin: G. Histos, web (tissue) (05 Mar 2000) |