title: Immunohistochemistry for BRAF V600E in the Differential Diagnosis of Hairy Cell Leukemia vs Other Splenic B-Cell Lymphomas.
abstract: OBJECTIVE
  Recent reports have used immunohistochemistry (IHC) with a mutation-specific antibody to detect the BRAF V600E mutation, which is found in nearly all cases of hairy cell leukemia (HCL). To date, however, only a small number of non-HCL, splenic B-cell lymphomas have been examined by IHC.
  
  
  METHODS
  We analyzed 121 cases, including 26 HCLs, 52 non-HCL splenic lymphomas, 22 chronic lymphocytic leukemias/small lymphocytic lymphomas (CLLs/SLLs), and 21 plasma cell neoplasms (PCNs) for BRAF V600E expression by IHC. Molecular testing for BRAF V600E was performed in a subset of cases, using allele-specific polymerase chain reaction and/or Sanger sequencing.
  
  
  RESULTS
  Twenty-six (100%) of 26 HCL cases were positive by IHC vs one (1%) of 95 non-HCL cases. Positive staining was identified in one (2%) of 44 splenic marginal zone lymphomas (SMZLs), while each of 22 CLLs/SLLs, 21 PCNs, six unclassifiable splenic lymphomas, and two HCL variants were negative. IHC and molecular results were concordant in all cases examined (21 HCLs and 21 non-HCLs, including the BRAF+ SMZLs).
  
  
  CONCLUSIONS
  The detection of BRAF V600E by IHC is useful in the distinction of HCLs from other splenic-based lymphomas, although the identification of at least rare SMZLs containing this abnormality illustrates the continuing need for a multiparameter approach to diagnosis.
authors.affiliation: From Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH, and.
authors.forename: Samir
authors.initials: S
authors.lastname: Turakhia
authors.affiliation: From Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH, and.
authors.forename: Christopher
authors.initials: C
authors.lastname: Lanigan
authors.affiliation: From Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH, and.
authors.forename: Fatima
authors.initials: F
authors.lastname: Hamadeh
authors.affiliation: Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA.
authors.forename: Steven H
authors.initials: SH
authors.lastname: Swerdlow
authors.affiliation: From Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH, and.
authors.forename: Raymond R
authors.initials: RR
authors.lastname: Tubbs
authors.affiliation: From Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH, and cookj2@ccf.org.
authors.forename: James R
authors.initials: JR
authors.lastname: Cook
mesh_terms: D000368:Aged; D004252:DNA Mutational Analysis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007943:Leukemia, Hairy Cell / Q000175:diagnosis* / Q000235:genetics*; D016393:Lymphoma, B-Cell / Q000175:diagnosis* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*
chemical_list: C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf
keywords: BRAF; Hairy cell leukemia; Immunohistochemistry