title: Diagnostic Usefulness of Claudin-3 and Claudin-4 for Immunocytochemical Differentiation between Metastatic Adenocarcinoma Cells and Reactive Mesothelial Cells in Effusion Cell Blocks.
abstract: OBJECTIVE
  Claudin-3 and claudin-4 have recently been reported as promising targets for the detection and diagnosis of cancer. This study was designed to evaluate the diagnostic value of claudin-3 and claudin-4 immunoreactivity to distinguish metastatic adenocarcinoma cells (MAC) from reactive mesothelial cells (RMC) in effusions.
  
  
  METHODS
  Claudin-3 and claudin-4 immunocytochemical staining was performed on 234 cell block specimens, including 194 malignant effusions with MAC and 40 benign effusions with RMC. Any degree of membranous staining was considered positive.
  
  
  RESULTS
  Claudin-3 was positive in 190 (97.9%) out of 194 cases with MAC and in 3 (7.5%) out of 40 cases with RMC. Claudin-4 immunoreactivity was seen in all 194 (100%) cases with MAC and in 11 (27.5%) out of 40 cases with RMC. In all claudin-3- or claudin-4-positive RMC samples, the area of positive staining was <25% of the cells. Claudin-3 and claudin-4 efficiently discriminated between MAC and RMC (p < 0.001 for both), and claudin-3 was more specific than claudin-4 in differentiating between MAC and RMC (p < 0.05).
  
  
  CONCLUSIONS
  These results suggest that claudin-3 and claudin-4 are good candidates to be included as MAC markers in the panel of antibodies to distinguish MAC from RMC in effusion specimens.
authors.affiliation: Department of Pathology, Chonnam National University Medical School, Gwangju, Republic of Korea.
authors.forename: Nah Ihm
authors.initials: NI
authors.lastname: Kim
authors.forename: Ga-Eon
authors.initials: GE
authors.lastname: Kim
authors.forename: Ji Shin
authors.initials: JS
authors.lastname: Lee
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D062465:Claudin-3 / Q000378:metabolism*; D062506:Claudin-4 / Q000378:metabolism*; D003937:Diagnosis, Differential; D004848:Epithelium / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis / Q000000981:diagnostic imaging* / Q000473:pathology; D010996:Pleural Effusion / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D016066:Pleural Effusion, Malignant / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D062465:Claudin-3; D062506:Claudin-4