Histiocyte: From 1 Different Sources
n. a fixed *macrophage, i.e. one that is stationary within connective tissue.
A rare childhood disease in which there is an overgrowth of a type of tissue cell called a histiocyte. The cause is unknown, but histiocytosis X probably results from a disturbance of the immune system. In the mildest form, rapid cell growth occurs in 1 bone only, usually the skull, a clavicle, a rib, or a vertebra, causing swelling and pain. In the most severe, and least common, form, there is a rash and enlargement of the liver, spleen, and lymph nodes.... histiocytosis x
a tumour probably derived from *histiocytes that may occur in any part of the body. It is locally invasive but tends not to metastasize. It often recurs locally despite excision.... dermatofibrosarcoma protuberans
n. a malignant tumour of connective tissue, derived from *fibroblasts. Fibrosarcomas may arise in soft tissue or bone; they can affect any organ but are most common in the limbs, particularly the leg. They occur in people of all ages and may be congenital. The cells of these tumours show varying degrees of differentiation; the less well differentiated tumours containing elements of histiocytes have been recently reclassified as malignant fibrous histiocytomas.... fibrosarcoma
n. (pl. granulomata or granulomas) a localized collection of cells, usually produced in response to an infectious process, that is characterized by the presence of aggregates of epithelioid *histiocytes; giant cells, monocytes, or lymphocytes may also be present. The types of cells comprising a granuloma (of which there may be many or few) and their arrangement can assist in diagnosing the cause of the response; this is important in the diagnosis of tuberculosis, sarcoidosis, Crohn’s disease, and the presence of certain foreign bodies (e.g. starch, talc). Other conditions giving rise to granulomata include syphilis, leprosy, and coccidioidomycosis, and a granuloma may also occur around the apex of a tooth root as a result of inflammation or infection of its pulp. —granulomatous adj.... granuloma
n. a tumour that contains *macrophages or *histiocytes, large cells with the ability to engulf foreign matter and bacteria. See also fibrosarcoma.... histiocytoma
n. any of a group of diseases in which there are abnormalities in certain large phagocytic cells (*histiocytes) due to (1) abnormal storage of fats, as in *Gaucher’s disease; (2) inflammatory disorders, as in *Langerhans cell histiocytosis, which includes disorders previously called histiocytosis X; or (3) malignant proliferation of histiocytes.... histiocytosis
n. a large scavenger cell (a *phagocyte) present in connective tissue and many major organs and tissues, including the bone marrow, spleen, *lymph nodes, liver (see Kupffer cells), and the central nervous system (see microglia). They are closely related to *monocytes. Fixed macrophages (histiocytes) are stationary within connective tissue; free macrophages wander between cells and aggregate at focal sites of infection, where they remove bacteria or other foreign bodies from blood or tissues. See also reticuloendothelial system.... macrophage
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