title: Differential diagnostic value of CD5 and CD117 expression in thoracic tumors: a large scale study of 1465 non-small cell lung cancer cases.
abstract: BACKGROUND
  Thoracic pathologists are frequently faced with tissue specimens from intrathoracic/mediastinal tumors. Specifically the differentiation between thymic and pulmonary squamous cell carcinomas (SqCC) can be challenging. In order to clarify the differential diagnostic value of CD5 and CD117 in this setting, we performed a large scale expression study of both markers in 1465 non-small cell lung cancer (NSCLC) cases.
  
  
  METHODS
  Tissue microarrays of formalin-fixed paraffin-embedded resection specimens of 1465 NSCLC were stained with antibodies against CD117 and CD5. Positivity of both markers was correlated with clinicopathological variables.
  
  
  RESULTS
  CD117 was positive in 145 out of 1457 evaluable cases (9.9 %) and CD5 was positive in 133 out of 1427 evaluable cases (9.3 %). 28 cases (1.9 %) showed coexpression of CD117 and CD5. Among the 145 cases that were positive for CD117, 97 (66.8 %) were adenocarcinomas (ADC), 34 (23.4 %) were SqCC, 5 (3.4 %) were adenosquamous carcinomas (ADSqCC), 8 (5.5 %) were large cell carcinomas (LC), and one (0.6 %) was a pleomorphic carcinoma (PC). In the CD5 positive group consisting of 133 cases, 123 (92.4 %) were ADC, 0 (0 %) were SqCC, 4 (3.0 %) were ADSqCC, 3 (2.2 %) LC and 3 (2.2 %) were PC. None of the 586 SqCC showed expression of CD5. No association of CD117- or CD5 positivity to patients' age, pathological stages or to T-, N-, or M- categories was observed.
  
  
  CONCLUSIONS
  A substantial subset of NSCLC exhibit positivity of CD117 and CD5. Since CD5 expression was not observed in pulmonary SqCC, but is expressed in the majority of thymic squamous cell carcinomas, the application of this immunomarker is a valuable tool in the differential diagnosis of thoracic neoplasms.
authors.affiliation: Institute of Pathology, Heidelberg University, Im Neuenheimer Feld 224, Heidelberg, Germany. mark.kriegsmann@med.uni-heidelberg.de.
authors.forename: Mark
authors.initials: M
authors.lastname: Kriegsmann
authors.affiliation: Translational Research Unit, Thoraxklinik at Heidelberg University, Heidelberg, Germany. Thomas.muley@med.uni-heidelberg.de.|Translational Lung Research Center (TLRC), Member of the German Center for Lung Research, Heidelberg, Germany. Thomas.muley@med.uni-heidelberg.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Muley
authors.affiliation: Institute of Pathology, Heidelberg University, Im Neuenheimer Feld 224, Heidelberg, Germany. Alexander.harms@med.uni-heidelberg.de.
authors.forename: Alexander
authors.initials: A
authors.lastname: Harms
authors.affiliation: Institute of Pathology, Heidelberg University, Im Neuenheimer Feld 224, Heidelberg, Germany. Luca.tavernar@med.uni-heidelberg.de.
authors.forename: Luca
authors.initials: L
authors.lastname: Tavernar
authors.affiliation: Clinical and Experimental Pathology, Research Center Borstel, Borstel, Germany. tgoldmann@fz-borstel.de.|Airway Research Center North (ARCN), Member of the German Center for Lung Research, Borstel, Germany. tgoldmann@fz-borstel.de.
authors.forename: Torsten
authors.initials: T
authors.lastname: Goldmann
authors.affiliation: Department of Thoracic Surgery, Thoraxklinik at Heidelberg University, Heidelberg, Germany. Hendrik.dienemann@med.uni-heidelberg.de.|Translational Lung Research Center (TLRC), Member of the German Center for Lung Research, Heidelberg, Germany. Hendrik.dienemann@med.uni-heidelberg.de.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Dienemann
authors.affiliation: Institute of Pathology, Heidelberg University, Im Neuenheimer Feld 224, Heidelberg, Germany. Ester.herpel@med.uni-heidelberg.de.
authors.forename: Esther
authors.initials: E
authors.lastname: Herpel
authors.affiliation: Institute of Pathology, Heidelberg University, Im Neuenheimer Feld 224, Heidelberg, Germany. Arne.warth@med.uni-heidelberg.de.|Translational Lung Research Center (TLRC), Member of the German Center for Lung Research, Heidelberg, Germany. Arne.warth@med.uni-heidelberg.de.
authors.forename: Arne
authors.initials: A
authors.lastname: Warth
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D018956:CD5 Antigens / Q000378:metabolism*; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D013945:Thymoma / Q000175:diagnosis* / Q000378:metabolism*; D013953:Thymus Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D018956:CD5 Antigens; D019009:Proto-Oncogene Proteins c-kit