title: CD30 expression in follicular lymphoma.
abstract: BACKGROUND
  CD30(+) anaplastic large cell lymphomas were originally described as being of T-cell, null cell, and B-cell origin. CD30, however, is not a specific marker of anaplastic large cell lymphoma and has been found to be expressed in reactive as well as neoplastic populations as a probable activation marker. In addition, CD30(+) cells have also been described in both diffuse large B-cell and follicular lymphomas (FLs), resembling the pattern seen in reactive tonsils and lymph nodes.
  
  
  OBJECTIVE
  We report an index case of FL with CD30 expression, which on initial touch preparations and flow cytometric immunophenotyping revealed a prominent population of CD30(+) cells with marked cellular pleomorphism (anaplasia) in a background of typical FL. Immunohistochemistry of the paraffin section for CD30 in our index case confirmed unequivocal CD30(+) pleomorphic cells in the malignant nodules in occasional clusters. This case prompted a study of additional cases of FL for pattern of immunoreactivity with CD30 on paraffin sections.
  
  
  METHODS
  Twenty-two additional cases of FL (grades 1-3) were retrieved for CD30 immunoperoxidase staining as in the index case.
  
  
  RESULTS
  This study demonstrated 32% of the additional cases of FL had definitive CD30(+), large, pleomorphic malignant cells by paraffin immunohistochemistry. In 2 cases (9%), the pattern of immunoreactivity with CD30 showed clustering and variable staining of large cells, as our index case.
  
  
  CONCLUSIONS
  This study underscores the morphologic and immunophenotypic spectrum of FL that includes CD30 staining and cellular pleomorphism.
authors.affiliation: Division of Hematopathology, Department of Pathology, St Louis University Health Sciences Center, St Louis, MO, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: Gardner
authors.forename: J M
authors.initials: JM
authors.lastname: Polski
authors.forename: H L
authors.initials: HL
authors.lastname: Evans
authors.forename: S L
authors.initials: SL
authors.lastname: Perkins
authors.forename: C H
authors.initials: CH
authors.lastname: Dunphy
mesh_terms: D000368:Aged; D001402:B-Lymphocytes / Q000473:pathology; D002883:Chromosomes, Human, Pair 14; D002887:Chromosomes, Human, Pair 18; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D016130:Immunophenotyping; D017730:Ki-1 Antigen / Q000032:analysis*; D008198:Lymph Nodes / Q000276:immunology / Q000473:pathology / Q000601:surgery; D008224:Lymphoma, Follicular / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D009333:Neck; D015260:Neprilysin / Q000032:analysis; D016133:Polymerase Chain Reaction; D014178:Translocation, Genetic
chemical_list: D017730:Ki-1 Antigen; D015260:Neprilysin