histiocytosis(redirected from histocytosis)
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Related to histocytosis: malignant histiocytosis, Langerhans cell histiocytosis, sinus histiocytosis, cutaneous histiocytosis
a condition marked by the abnormal appearance of histiocytes in the blood.
Langerhans cell histiocytosis a generic term that encompasses a group of disorders characterized by proliferation of Langerhans cells, which are specialized cells found in the epidermis that function as part of the immune system. These disorders are believed to arise from disturbances in regulation of the immune system. Children are more often affected than adults, and the bone marrow, endocrine system, and lungs may be involved (the lungs are affected more commonly in adults than in children). Langerhans cell histiocytosis is divided into unifocal and multifocal variants; there is also an acute, disseminated form (letterer-siwe disease). This group of disorders was formerly called histiocytosis X and was classified in three forms: Letterer-Siwe disease, Hand-Schüller-Christian disease, and eosinophilic granuloma. Called also eosinophilic granuloma, eosinophilic granulomatosis, and Langerhans cell granulomatosis.
Langerhans cell histiocytosis, acute disseminated Letterer-Siwe disease.
Langerhans cell histiocytosis, multifocal Langerhans cell histiocytosis occurring as erosive accumulations of proliferating Langerhans cells. It occurs most commonly in the marrow cavities of bones, but may also affect the skin, gingiva, lungs, and stomach. When the triad of involvement of the bones of the skull, exophthalmos, and diabetes insipidus is present, it is referred to as Hand-Schüller-Christian disease.
Langerhans cell histiocytosis, unifocal Langerhans cell histiocytosis occurring as a single osteolytic lesion, usually in a long or flat bone; it may be asymptomatic or may produce bone pain, tenderness, and swelling and, sometimes, pathologic fracture.
histiocytosis X former name for Langerhans cell histiocytosis.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
A generalized proliferation of histiocytes.
Farlex Partner Medical Dictionary © Farlex 2012
n. pl. histiocyto·ses (-sēz)
Any of several diseases characterized by the abnormal proliferation of histiocytes in the tissues or organs.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
A generalized multiplication of histiocytes.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
histiocytosisOne of several disorders in which HISTIOCYTES occur in abnormal numbers, in localized areas, without any of the usual causes, such as infection. Histiocytosis LESIONS may be single or multiple. The condition is also known as histiocytosis X.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005