title: Large B-cell lymphomas poor in B cells and rich in PD-1+ T cells can mimic T-cell lymphomas.
abstract: OBJECTIVE
  To characterize the clinicopathologic features of cases of large B-cell lymphomas, poor in B cells and densely rich in programmed cell death-1 (PD-1)+ reactive T cells, which can mimic T-cell lymphomas.
  
  
  METHODS
  A single-institute retrospective review of cases between 2010 and 2013 was performed.
  
  
  RESULTS
  Of 178 cases of large B-cell lymphomas, eight cases of large B-cell lymphomas poor in B cells and diffusely rich in sheets of PD-1+ T cells were identified. These cases either were initially misdiagnosed as a T-cell lymphoma or substantiated a broader differential diagnosis including a T-cell lymphoma. Five cases were T-cell histiocyte-rich large B-cell lymphomas, and three cases were diagnosed as large B-cell lymphomas rich in T cells. In three of these cases, a subset of the PD-1+ T cells showed either morphologic nuclear atypia or atypical expression of T-cell antigens on flow cytometry and/or immunohistochemistry.
  
  
  CONCLUSIONS
  Large B-cell lymphomas poor in B cells and rich in T cells can have diffuse sheets of reactive PD-1+ T cells, some with atypical morphologic and immunophenotypic features mimicking a T-cell lymphoma. Careful assessment of the immunoarchitecture and background inflammatory and stromal cells can prevent erroneous diagnoses in such cases.
authors.affiliation: From Stanford University Medical Center, Stanford, CA. rohgami@stanford.edu.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Ohgami
authors.affiliation: From Stanford University Medical Center, Stanford, CA.
authors.forename: Shuchun
authors.initials: S
authors.lastname: Zhao
authors.affiliation: From Stanford University Medical Center, Stanford, CA.
authors.forename: Yasodha
authors.initials: Y
authors.lastname: Natkunam
mesh_terms: D000293:Adolescent; D000328:Adult; D001402:B-Lymphocytes / Q000166:cytology*; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping / Q000379:methods; D018655:Lymphocyte Count; D016393:Lymphoma, B-Cell / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D016399:Lymphoma, T-Cell / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D061026:Programmed Cell Death 1 Receptor / Q000378:metabolism*; D012189:Retrospective Studies; D013601:T-Lymphocytes / Q000166:cytology*; D055815:Young Adult
chemical_list: C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor
keywords: Large B-cell lymphoma; PD-1+ T cells; T-cell histiocyte rich large B-cell lymphoma