title: Hemophagocytosis by leukemic blasts in 7 acute myeloid leukemia cases with t(16;21)(p11;q22): common morphologic characteristics for this type of leukemia.
abstract: BACKGROUND
  In a previous study of a case of acute megakaryoblastic leukemia with t(16;21)(p11;q22), which displayed hemophagocytosis by leukemic blasts, the authors mentioned that the same type of morphology had been cited in the literature for 4 other cases of acute myeloid leukemia (AML) with the same translocation. This observation prompted the authors to examine more cases of AML with t(16;21)(p11;q22) for this morphology.
  
  
  METHODS
  The authors reviewed bone marrow smears for the presence of hemophagocytosis in 7 patients with AML identified as having t(16;21)(p11;q22).
  
  
  RESULTS
  The leukemias belonged to the FAB-M1/M7 (n = 5), M5b (n = 2), and contained phagocytic blasts in various percentages (< 0.2-36.7%). The blasts contained either single or multiple cytoplasmic vacuoles, in some of which the phagosomes were visible. The engulfed hemopoietic cells (red cells, erythroblasts, lymphocytes, and thrombocytes) were also noted in their cytoplasm. These observations confirmed that hemophagocytosis by leukemic blasts is a common and characteristic feature of this type of leukemia.
  
  
  CONCLUSIONS
  The study of 12 cases (the 7 cases described here and the previous 5 cases) strongly supports the hypothesis that hemophagocytosis by leukemic blasts is common and characteristic in this type of leukemia, which may be related to the specific chromosome aberration of t(16;21)(p11;q22).
authors.affiliation: Division of Pediatrics, Children's Research Hospital, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Imashuku
authors.forename: S
authors.initials: S
authors.lastname: Hibi
authors.forename: M
authors.initials: M
authors.lastname: Sako
authors.forename: Y W
authors.initials: YW
authors.lastname: Lin
authors.forename: K
authors.initials: K
authors.lastname: Ikuta
authors.forename: Y
authors.initials: Y
authors.lastname: Nakata
authors.forename: T
authors.initials: T
authors.lastname: Mori
authors.forename: S
authors.initials: S
authors.lastname: Iizuka
authors.forename: K
authors.initials: K
authors.lastname: Horibe
authors.forename: Y
authors.initials: Y
authors.lastname: Tsunematsu
mesh_terms: D000293:Adolescent; D001752:Blast Crisis / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D002885:Chromosomes, Human, Pair 16 / Q000235:genetics*; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D005260:Female; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000097:blood / Q000235:genetics* / Q000473:pathology; D008297:Male; D010587:Phagocytosis; D014178:Translocation, Genetic