title: Clinicopathologic evaluation of MYC expression in primary mediastinal (thymic) large B-cell lymphoma.
abstract: OBJECTIVE
  Based on previous molecular studies, a small fraction of primary mediastinal (thymic) large B-cell lymphoma (PMBL) demonstrates MYC alterations. However, no studies have evaluated MYC protein expression by immunohistochemistry (IHC) with follow-up fluorescence in situ hybridization (FISH) analysis. We aim to evaluate the clinicopathologic importance of MYC IHC expression in PMBL.
  
  
  METHODS
  Three pathologists independently evaluated MYC IHC expression in 32 cases of PMBL for percent tumor positivity and nuclear intensity. FISH analysis for MYC rearrangement was performed on cases with high MYC IHC expression. Clinical data including treatment, follow-up, and outcome were also reviewed in a subset of cases.
  
  
  RESULTS
  Variable MYC protein expression by IHC was detected in 30 (94%) of 32 cases of PMBL. One-third of the positive cases (10/30) showed high MYC IHC expression of at least 30% nuclear positivity. FISH analyses for MYC rearrangement on these 10 cases were negative. Review of clinical data on a subset of cases with high and low MYC IHC expression showed no differences in clinical outcome.
  
  
  CONCLUSIONS
  MYC protein expression by IHC is present in most PMBLs. Increased MYC protein expression can be seen in one-third of the cases; however, it does not correlate with genetic abnormalities by FISH. There is also no significant impact of MYC protein expression on clinical outcomes.
authors.affiliation: From the Department of Pathology, University of Utah and ARUP Laboratories, Salt Lake City;
authors.forename: K David
authors.initials: KD
authors.lastname: Li
authors.affiliation: From the Department of Pathology, University of Utah and ARUP Laboratories, Salt Lake City;
authors.forename: Rodney
authors.initials: R
authors.lastname: Miles
authors.affiliation: ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT; and.
authors.forename: Sheryl R
authors.initials: SR
authors.lastname: Tripp
authors.affiliation: University of Utah School of Medicine, Salt Lake City.
authors.forename: Martha J
authors.initials: MJ
authors.lastname: Glenn
authors.affiliation: From the Department of Pathology, University of Utah and ARUP Laboratories, Salt Lake City;
authors.forename: Sherrie L
authors.initials: SL
authors.lastname: Perkins
authors.affiliation: From the Department of Pathology, University of Utah and ARUP Laboratories, Salt Lake City; salama@path.utah.edu.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Salama
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D016393:Lymphoma, B-Cell / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008479:Mediastinal Neoplasms / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism*; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc
keywords: Immunohistochemistry; MYC; Primary mediastinal large B-cell lymphoma