title: MUM1 expression in cutaneous CD30+ lymphoproliferative disorders: a valuable tool for the distinction between lymphomatoid papulosis and primary cutaneous anaplastic large-cell lymphoma.
abstract: BACKGROUND
  Primary cutaneous CD30+ lymphoproliferative disorders include lymphomatoid papulosis (LyP) and primary cutaneous CD30+ anaplastic large T-cell lymphoma (ALCL). Because of overlapping histological features, it is impossible to distinguish ALCL from LyP on histological grounds. MUM1 (Multiple Myeloma oncogene 1) is expressed in systemic ALCL and classical Hodgkin lymphoma. MUM1 expression has not been studied in detail in CD30+ lymphoproliferative disorders.
  
  
  OBJECTIVE
  To examine the expression of MUM1 in CD30+ lymphoproliferative disorders and to assess its value as a diagnostic marker.
  
  
  METHODS
  Thirty-one formalin-fixed paraffin-embedded specimens of LyP (n = 15), primary cutaneous ALCL (n = 10), secondary cutaneous infiltrates of systemic ALCL (n = 4) and secondary cutaneous Hodgkin lymphoma (n = 2) were analysed by immunohistochemistry with a monoclonal antibody against MUM1.
  
  
  RESULTS
  Positive staining for MUM1 was observed in 13 cases of LyP (87%), two cases of primary cutaneous ALCL (20%), four cases of secondary cutaneous ALCL (100%) and two cases of secondary cutaneous Hodgkin lymphoma (100%). In 11 of 13 LyP cases (85%), MUM1 was displayed by the majority, i.e. 50-90%, of the tumour cells. In contrast to LyP and secondary cutaneous ALCL, only two cases of primary cutaneous ALCL (20%) harboured MUM1-positive tumour cells. There was a statistically significant difference in the expression of MUM1 between LyP and primary cutaneous ALCL (P = 0.002) and between primary cutaneous ALCL and secondary cutaneous ALCL (P = 0.015).
  
  
  CONCLUSIONS
  MUM1 expression is a valuable tool for the distinction of LyP and ALCL and thus represents a novel adjunctive diagnostic marker in CD30+ lymphoproliferative disorders.
authors.affiliation: Kempf und Pfaltz, Histologische Diagnostik, Schaffhauserplatz 3, CH-8006 Zurich, Switzerland. kempf@kempf-pfaltz.ch
authors.forename: W
authors.initials: W
authors.lastname: Kempf
authors.forename: H
authors.initials: H
authors.lastname: Kutzner
authors.forename: A
authors.initials: A
authors.lastname: Cozzio
authors.forename: C A
authors.initials: CA
authors.lastname: Sander
authors.forename: M C
authors.initials: MC
authors.lastname: Pfaltz
authors.forename: B
authors.initials: B
authors.lastname: Müller
authors.forename: M
authors.initials: M
authors.lastname: Pfaltz
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism*; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D050835:Interferon Regulatory Factors / Q000378:metabolism*; D017730:Ki-1 Antigen; D017728:Lymphoma, Large-Cell, Anaplastic / Q000175:diagnosis / Q000378:metabolism; D017731:Lymphomatoid Papulosis / Q000175:diagnosis / Q000378:metabolism; D008232:Lymphoproliferative Disorders / Q000175:diagnosis* / Q000378:metabolism; D009101:Multiple Myeloma / Q000175:diagnosis / Q000378:metabolism; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D000099218:Interferon Regulatory Factor-4
chemical_list: D014408:Biomarkers, Tumor; D050835:Interferon Regulatory Factors; D017730:Ki-1 Antigen; D000099218:Interferon Regulatory Factor-4