title: Eosinophilic leukaemias and the idiopathic hypereosinophilic syndrome.
abstract: Hypereosinophilic syndromes may result either from eosinophilic differentiation of a clone of neoplastic cells or from reactive eosinophilia. In other patients HES is idiopathic. It appears likely that in many patients the "idiopathic' hypereosinophilic syndrome is actually a chronic myeloproliferative disorder. Those cases showing an increase of blast cells or a demonstrable clonal cytogenetic abnormality should be classified as eosinophilic leukaemia. In other cases the neoplastic nature of the disease can be recognized only in retrospect when a granulocytic sarcoma or AMI, develops. A few cases of idiopathic HES are consequent on cytokine secretion whereas others remain idiopathic at the time of death. When eosinophilia occurs as a feature of an acute or chronic myeloid leukaemia or a chronic myeloproliferative disorder the eosinophils are usually part of the leukaemic clone. However, eosinophilia in association with acute lymphoblastic leukaemia is usually reactive. Rare cases have a biphenotypic leukaemia/lymphoma with both eosinophils and lymphoid cells arising from a mutant pluripotent stem cell.
authors.affiliation: Department of Haematology, Imperial College School of Medicine, St Mary's Hospital, London.
authors.forename: B J
authors.initials: BJ
authors.lastname: Bain
mesh_terms: D000208:Acute Disease; D002455:Cell Division; D004804:Eosinophils / Q000473:pathology*; D006801:Humans; D017681:Hypereosinophilic Syndrome / Q000235:genetics / Q000473:pathology; D007951:Leukemia, Myeloid / Q000473:pathology; D014178:Translocation, Genetic