title: Detection of the CD56+/CD45- immunophenotype by flow cytometry in neuroendocrine malignancies.
abstract: OBJECTIVE
  Antibodies against CD56 are primarily used in flow cytometric studies to detect natural killer cells. However, they may be useful in the identification of neuroendocrine malignancies, especially if the cells do not express CD45, indicating a non-leucocyte origin.
  
  
  METHODS
  A retrospective review was conducted on all solid tissue flow cytometric studies performed between January 1997 and September 2001, to identify all cases with a CD56+/CD45- immunophenotype.
  
  
  RESULTS
  Twelve neuroendocrine malignancies (five metastatic small cell carcinomas, three Merkel cell carcinomas, two metastatic undifferentiated neuroendocrine carcinomas, one metastatic pancreatic neuroendocrine carcinoma, and one neuroblastoma) were identified.
  
  
  CONCLUSIONS
  CD56+/CD45- neuroendocrine malignancies are only rarely detected in the flow cytometric analysis of solid tissue samples. However, the recognition of this immunophenotype is important to avoid their misclassification as natural killer cell malignancies. Furthermore, flow cytometry assists in the rapid identification of such cases, so that appropriate immunohistochemical studies can be performed to facilitate their correct diagnosis.
authors.affiliation: Division of Immunology, Queensland Health Pathology Services, Royal Brisbane Hospital, Herston, Queensland 4029, Australia.
authors.forename: G J
authors.initials: GJ
authors.lastname: Bryson
authors.forename: D
authors.initials: D
authors.lastname: Lear
authors.forename: R
authors.initials: R
authors.lastname: Williamson
authors.forename: R C W
authors.initials: RC
authors.lastname: Wong
mesh_terms: D000951:Antigens, Neoplasm / Q000032:analysis*; D019002:CD56 Antigen / Q000032:analysis*; D005434:Flow Cytometry; D006801:Humans; D016130:Immunophenotyping; D017493:Leukocyte Common Antigens / Q000032:analysis*; D018358:Neuroendocrine Tumors / Q000175:diagnosis* / Q000276:immunology; D012189:Retrospective Studies
chemical_list: D000951:Antigens, Neoplasm; D019002:CD56 Antigen; D017493:Leukocyte Common Antigens