title: Large-cell transformation following detection of minimal residual disease in cutaneous T-cell lymphoma: molecular and in situ analysis of a single neoplastic T-cell clone expressing the identical T-cell receptor.
abstract: OBJECTIVE
  One of the unique characteristics of cutaneous T-cell lymphoma (CTCL) is its ability to undergo cytologic transformation in which the malignant T cells develop the morphologic appearance of a large-cell lymphoma. Reported to occur in up to 20% of advanced cases, large-cell transformation (LCT) is associated with an aggressive clinical course. Little is known about the risk factors or the molecular mechanisms of LCT. Before current immunohistochemical and molecular techniques, it was not possible to determine if LCT represented changes of the initial neoplastic T-cell clone or, in fact, was a distinct second malignancy. The goal of this study was to define the clonal evolution of LCT in CTCL.
  
  
  METHODS
  Polymerase chain reaction (PCR) amplification of T-cell receptor-beta (TCR-beta) gene rearrangements and immunohistochemistry with monoclonal antibodies to TCR-V beta regions were used as markers of T-cell clonality to analyze the skin and peripheral blood of a patient with CTCL and LCT.
  
  
  RESULTS
  We first detected the presence of minimal residual disease (MRD) in a CTCL patient with a complete clinical response to biologic response modifiers (BRMs). When clinical relapse occurred and demonstrated LCT, TCR-beta-PCR and in situ immunohistochemistry with a specific TCR-V beta monoclonal antibody identified a single neoplastic T-cell clone that expressed the identical TCR as the original clone.
  
  
  CONCLUSIONS
  Our results confirm a common clonal origin for CTCL and LCT. We also provide evidence of MRD in CTCL by molecular analysis, implying that residual malignant cells maintain a potential for clinical relapse and possibly LCT. The role of MRD detection remains to be defined in the clinical assessment of CTCL. LCT in CTCL provides a unique model to investigate the molecular events that underlie terminal-stage tumor progression.
authors.affiliation: Department of Dermatology, University of Pennsylvania Medical Center, Philadelphia, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Wolfe
authors.forename: L
authors.initials: L
authors.lastname: Chooback
authors.forename: D T
authors.initials: DT
authors.lastname: Finn
authors.forename: C
authors.initials: C
authors.lastname: Jaworsky
authors.forename: A H
authors.initials: AH
authors.lastname: Rook
authors.forename: S R
authors.initials: SR
authors.lastname: Lessin
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000473:pathology; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor / Q000235:genetics*; D005819:Genetic Markers; D006801:Humans; D007155:Immunologic Factors / Q000627:therapeutic use; D016403:Lymphoma, Large B-Cell, Diffuse / Q000235:genetics / Q000473:pathology; D016410:Lymphoma, T-Cell, Cutaneous / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D018365:Neoplasm, Residual; D016133:Polymerase Chain Reaction
chemical_list: D005819:Genetic Markers; D007155:Immunologic Factors