title: Reactive and neoplastic lymphocytes in human bone marrow: morphological, immunohistological, and molecular biological investigations on biopsy specimens.
abstract: BACKGROUND
  Slight, diffuse or focal lymphocyte proliferation is relatively common in bone marrow biopsy specimens. It may be impossible to determine whether this represents a reactive lymphocytosis or low grade non-Hodgkin lymphoma (NHL) on the basis of routine investigations alone.
  
  
  OBJECTIVE
  To investigate the supplementary use of molecular biological techniques in this situation.
  
  
  METHODS
  529 formalin fixed, paraffin embedded bone marrow biopsy specimens from the iliac crest were subjected to histological and immunohistochemical staining to determine the number and nature of the lymphocytes present. The cases were divided into three groups according to the lymphocyte count: normal (< 10% of nucleated bone marrow cells), slightly increased (10-30%), and markedly increased (> 30%). All of the last group could be diagnosed as NHL from the morphological findings alone. The clonality of rearrangements of the IgH and TCR gamma genes was investigated by polymerase chain reaction (PCR).
  
  
  RESULTS
  Monoclonality was observed in 7.5% of the 372 cases with a normal lymphocyte count, in 50% of the cases with a modest increase in lymphocyte numbers (suggesting a diagnosis of low grade NHL not detected by immunostaining), and in 77% of the cases with markedly increased lymphocyte numbers.
  
  
  CONCLUSIONS
  If PCR is used in addition to the immunohistochemical investigation of bone marrow biopsies, considerably more cases of NHL can be identified, making this of particular use in staging and detection of recurrences.
authors.affiliation: Institute of Pathology, Eberhard-Karls-Universität, Tübingen, Germany. stefan-martin.kroeber@med.uni-tübingen.de
authors.forename: S M
authors.initials: SM
authors.lastname: Kröber
authors.forename: H P
authors.initials: HP
authors.lastname: Horny
authors.forename: A
authors.initials: A
authors.lastname: Greschniok
authors.forename: E
authors.initials: E
authors.lastname: Kaiserling
mesh_terms: D001854:Bone Marrow Cells / Q000276:immunology*; D003937:Diagnosis, Differential; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D015334:Gene Rearrangement, gamma-Chain T-Cell Antigen Receptor; D006801:Humans; D007150:Immunohistochemistry; D018655:Lymphocyte Count; D008218:Lymphocytosis / Q000175:diagnosis / Q000235:genetics / Q000276:immunology; D008228:Lymphoma, Non-Hodgkin / Q000175:diagnosis* / Q000235:genetics / Q000276:immunology; D016399:Lymphoma, T-Cell / Q000175:diagnosis / Q000235:genetics / Q000276:immunology; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity