title: Malignant histiocytosis in the leukaemic stage: a new entity (M5c-AML) in the FAB classification?
abstract: Malignant histiocytosis (MH) is a rare, rapidly fatal disorder, characterized by systemic proliferation of abnormal histiocytes. Most patients present with pancytopenia. We report the case of a patient with MH in the leukaemic stage, who presented extremely pronounced general symptoms and multisystemic involvement. Determination of serum cytokines showed high levels of tumor necrosis factor (TNF), interleukin 6 (IL-6) and interleukin 1 receptor antagonist (IL-1ra). Cytogenetic studies proved the monoclonality of the histiocytic proliferation. These findings strongly suggest that we are dealing with a proliferation of activated macrophages (= histiocytes). By analogy with the monoblastic (M5a) and monocytic (M5b) acute leukaemia of the French-American-British (FAB) classification, we propose a new entity, 'M5c', designating acute histiocytic leukaemia.
authors.affiliation: Division of Hematology, Hôpital Cantonal Universitaire, Geneva, Switzerland.
authors.forename: F M
authors.initials: FM
authors.lastname: Laurencet
authors.forename: B
authors.initials: B
authors.lastname: Chapuis
authors.forename: P
authors.initials: P
authors.lastname: Roux-Lombard
authors.forename: J M
authors.initials: JM
authors.lastname: Dayer
authors.forename: P
authors.initials: P
authors.lastname: Beris
mesh_terms: D001853:Bone Marrow / Q000473:pathology; D016207:Cytokines / Q000097:blood*; D017809:Fatal Outcome; D054747:Histiocytic Sarcoma / Q000097:blood / Q000145:classification* / Q000473:pathology; D006801:Humans; D006965:Hyperplasia; D007948:Leukemia, Monocytic, Acute / Q000145:classification / Q000473:pathology; D008262:Macrophage Activation; D008297:Male; D008875:Middle Aged
chemical_list: D016207:Cytokines