title: Histiocytoses.
abstract: Childhood histiocytoses are a rare and diverse group of histiocytic disorders. This review will focus on clinical, pathological and immunopathological features of these syndromes. The pathogenesis of Langerhans' cell histiocytosis or class I histiocytosis, a proliferative disorder of the Langerhans' cell, remains enigmatic. Approaches to treatment are as varied as the clinical presentations, ranging from a fatal leukaemia-like disorder to solitary lytic lesions of bone. Recent findings indicate that Langerhans' cell histiocytosis is a clonal histiocytic disease. The two major class II histiocytoses are familial erythrophagocytic lymphohistiocytosis and the reactive haemophagocytic syndromes. The clinicopathological similarities between these two entities suggest that they share a common immunological feature in which uncontrolled cytokine release from activated T-cells leads macrophages to a haemophagocytosing state.
authors.affiliation: Unité d'Hématologie et Oncologie Pédiatrique, Hôpital Nord, Centre Hospitalier Universitaire, Saint Etienne, France.
authors.forename: J L
authors.initials: JL
authors.lastname: Stéphan
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D016207:Cytokines / Q000502:physiology; D015614:Histiocytosis / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D006801:Humans; D007223:Infant; D007801:Langerhans Cells / Q000276:immunology / Q000473:pathology; D008213:Lymphocyte Activation / Q000276:immunology; D008262:Macrophage Activation / Q000276:immunology; D008264:Macrophages / Q000276:immunology / Q000473:pathology
chemical_list: D016207:Cytokines