title: CD5 expression identifies a subset of splenic marginal zone lymphomas with higher lymphocytosis: a clinico-pathological, cytogenetic and molecular study of 24 cases.
abstract: BACKGROUND
  Classically, splenic marginal zone B-cell lymphoma is characterized by the absence of CD5 expression. Cases of apparent splenic marginal zone B-cell lymphoma showing CD5 expression, as diagnosed by blood studies, have been described; however, in the absence of histological evidence, the correct diagnosis of these cases is controversial because of possible confusion with other CD5-positive small B-cell neoplasms.
  
  
  METHODS
  We report a series of 24 CD5-positive, t(11;14)-negative cases of splenic marginal zone B-cell lymphoma diagnosed by flow cytometry studies of blood and histologically proven on spleen sections. Clinical data as well as morphological, immunological, cytogenetic and molecular characteristics were assessed to evaluate the similarities and differences of these cases with those of classical CD5-negative splenic marginal zone B-cell lymphoma.
  
  
  RESULTS
  The CD5 expression detected in blood by flow cytometry was confirmed in most cases by immunohistochemistry on spleen sections. In general, cases of CD5-positive and CD5-negative splenic marginal zone B-cell lymphoma did not appear different and, in particular, they showed similar karyotypic changes such as 7q deletion, trisomy 3, trisomy 18 and biased IGHV usage (i.e. VH1-2). The main differences were a higher lymphocyte count at diagnosis (8.15x10(9)/L versus 3.90x10(9)/L; P=0.005) and more frequent diffuse bone marrow infiltration (34% versus 8%; P=0.03) in the CD5-positive group. A tendency to a more mutated IGHV status in the CD5 positive cases was observed (80% versus 54.5%; (P=0.11). No significant differences in outcome were found in relation to CD5 expression.
  
  
  CONCLUSIONS
  This study confirms the existence of cases of CD5-positive splenic marginal zone B-cell lymphoma and shows that these cases are closely related to classical splenic marginal zone lymphoma. Whether or not CD5-positive splenic marginal zone B-cell lymphoma constitutes a true subset obviously requires the study of more cases.
authors.affiliation: Laboratoire d'Hématologie Cellulaire Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Lyon.
authors.forename: Lucile
authors.initials: L
authors.lastname: Baseggio
authors.forename: Alexandra
authors.initials: A
authors.lastname: Traverse-Glehen
authors.forename: Florence
authors.initials: F
authors.lastname: Petinataud
authors.forename: Evelyne
authors.initials: E
authors.lastname: Callet-Bauchu
authors.forename: Françoise
authors.initials: F
authors.lastname: Berger
authors.forename: Martine
authors.initials: M
authors.lastname: Ffrench
authors.forename: Chantal Marie
authors.initials: CM
authors.lastname: Couris
authors.forename: Catherine
authors.initials: C
authors.lastname: Thieblemont
authors.forename: Dominique
authors.initials: D
authors.lastname: Morel
authors.forename: Bertrand
authors.initials: B
authors.lastname: Coiffier
authors.forename: Gilles
authors.initials: G
authors.lastname: Salles
authors.forename: Pascale
authors.initials: P
authors.lastname: Felman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018956:CD5 Antigens / Q000378:metabolism*; D002880:Chromosomes, Human, Pair 11 / Q000235:genetics; D002883:Chromosomes, Human, Pair 14 / Q000235:genetics; D020732:Cytogenetic Analysis; D005260:Female; D005434:Flow Cytometry; D005500:Follow-Up Studies; D006801:Humans; D007124:Immunoenzyme Techniques; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D016130:Immunophenotyping; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism; D008218:Lymphocytosis / Q000473:pathology*; D018442:Lymphoma, B-Cell, Marginal Zone / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism*; D020522:Lymphoma, Mantle-Cell / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D013160:Splenic Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism*; D014178:Translocation, Genetic; D008258:Waldenstrom Macroglobulinemia / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism
chemical_list: D018956:CD5 Antigens; D007143:Immunoglobulin Heavy Chains