title: Predictive significance of absolute lymphocyte count and morphology in adults with a new onset peripheral blood lymphocytosis.
abstract: OBJECTIVE
  Lymphocytosis is commonly encountered in the haematology laboratory. Evaluation of blood films is an important screening tool for differentiating between reactive and malignant processes. The optimal lymphocyte number to trigger morphological evaluation of the smear has not been well defined in the literature. Likewise, the significance of lymphocyte morphology has not been well studied and there are no consensus guidelines or follow-up recommendations available. We attempt to evaluate the significance of lymphocyte morphology and to define the best possible cut-off value of absolute lymphocyte count for morphology review.
  
  
  METHODS
  71 adult patients with newly detected lymphocytosis of 5.0×10(9)/L or more were categorised to either a reactive process or a lymphoproliferative disorder. We performed statistical analysis and morphology review to compare the difference in age, gender, lymphocyte count and morphological features between the two groups. Receiver operating characteristic analysis was performed to determine an optimal lymphocyte number to trigger morphology review.
  
  
  RESULTS
  Lymphoproliferative disorders are associated with advanced age and higher lymphocyte count. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of lymphocyte morphology as a screening test were 0.9, 0.59, 0.60, 0.58 and 0.71, respectively. The optimal cut-off of lymphocyte number for morphology review was found to be close to 7×10(9)/L.
  
  
  CONCLUSIONS
  We found a moderate interobserver agreement for the morphological assessment. 'Reactive' morphology was very predictive of a reactive process, but 'malignant' morphology was a poor predictor of a lymphoproliferative disorder.
authors.affiliation: Division of Hematopathology, Diagnostic Services Manitoba and University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Ping
authors.initials: P
authors.lastname: Sun
authors.affiliation: School of Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: Emilia M
authors.initials: EM
authors.lastname: Kowalski
authors.affiliation: Division of Hematopathology, Department of Pathology and Laboratory Medicine, QEII Health Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Calvino K
authors.initials: CK
authors.lastname: Cheng
authors.affiliation: Division of Hematopathology, Department of Pathology and Laboratory Medicine, QEII Health Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Allam
authors.initials: A
authors.lastname: Shawwa
authors.affiliation: Division of Hematopathology, Department of Pathology and Laboratory Medicine, QEII Health Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Liwski
authors.affiliation: Department of Pathology & Laboratory Medicine, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA.
authors.forename: Ridas
authors.initials: R
authors.lastname: Juskevicius
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D018655:Lymphocyte Count / Q000379:methods*; D008214:Lymphocytes / Q000473:pathology*; D008218:Lymphocytosis / Q000175:diagnosis* / Q000209:etiology*; D008232:Lymphoproliferative Disorders / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D055815:Young Adult
keywords: LYMPHOCYTES; MORPHOLOGY; diagnostic screening