title: [Late-onset neutropenia following rituximab therapy as a treatment of diffuse large B-cell lymphoma: a single institution study].
abstract: BACKGROUND
  Late-onset neutropenia (LON) following rituximab therapy has been reported in recent years. However, its incidence has not been reported in Korea. The aim of this study is to investigate the incidence of LON after rituximab therapy in Korean patients with diffuse large B-cell lymphoma (DLBCL).
  
  
  METHODS
  Ninety-eight cases of DLBCL treated with rituximab between 2004 and 2008 were evaluated. We identified LON as defined by the neutrophil count of <1.5 × 10(9)/L without apparent cause after the recovery of neutrophil count following rituximab therapy. Bone marrow aspiration and biopsy specimens at the time of neutropenia were available for retrospective review in only 5 of the patients.
  
  
  RESULTS
  LON was observed in 15 (15.3%) of the 98 patients. In the bone marrow specimens of the 5 patients, promyelocytes were relatively increased and the maturation index of the granulopoiesis was 2:1-3:1, which reflects maturation arrest.
  
  
  CONCLUSIONS
  The incidence of LON following rituximab therapy was 15.3% in Korean patients with DLBCL. Although there are several hypotheses about the causative mechanisms of LON, we suggest that maturation arrest at the promyelocyte stage of granulopoiesis may be one of the mechanisms involved in the development of LON.
authors.affiliation: Department of Laboratory Medicine, Korea Cancer Center Hospital, Seoul, Korea.
authors.forename: Minki
authors.initials: M
authors.lastname: Kim
authors.forename: Jin Kyung
authors.initials: JK
authors.lastname: Lee
authors.forename: Young Jun
authors.initials: YJ
authors.lastname: Hong
authors.forename: Seok-Il
authors.initials: SI
authors.lastname: Hong
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Kang
authors.forename: Yoon Hwan
authors.initials: YH
authors.lastname: Chang
mesh_terms: D000328:Adult; D000368:Aged; D058846:Antibodies, Monoclonal, Murine-Derived / Q000009:adverse effects / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001854:Bone Marrow Cells / Q000473:pathology; D002454:Cell Differentiation; D005260:Female; D006801:Humans; D016403:Lymphoma, Large B-Cell, Diffuse / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D009503:Neutropenia / Q000175:diagnosis / Q000453:epidemiology*; D012189:Retrospective Studies; D000069283:Rituximab
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D000970:Antineoplastic Agents; D000069283:Rituximab