title: The diagnostic value of Ki-67 and repp86 in distinguishing between benign and malignant mesothelial proliferations.
abstract: BACKGROUND
  The differentiation of benign mesothelial proliferations from malignant mesotheliomas may be difficult, especially when evaluating small specimens from pleural biopsies.
  
  
  OBJECTIVE
  To explore the potential value of 2 proliferative cell markers, Ki-67 and restrictedly expressed proliferation-associated protein 86 kDa (repp86), in distinguishing between malignant mesothelioma (MM) and benign reactive mesothelial hyperplasia (MH).
  
  
  METHODS
  Thirty-six cases of MM from 26 men and 10 women with a mean age of 62.9 years (range, 36-80 years) and 22 cases of benign reactive MH from 14 male and 8 female patients with a mean age of 51.5 years (range, 15- 88 years) were included in this study. The proliferative status of the lesions was assessed by immunohistochemistry using monoclonal antibodies to Ki-S2 (repp86) and Ki-S5 (Ki-67). The labeling indices were quantified.
  
  
  RESULTS
  The mean labeling indexes for Ki-67 in MM and benign reactive MH were 24.6% (range, 1%-66%) and 6.23% (range, 0%-25%), respectively. The mean labeling indexes for repp86 in MM and benign reactive MH were 26.3% (range, 0%-50%) and 3.26% (range, 0%- 21%), respectively. The average proliferative cell count was significantly higher in MM compared with benign reactive MH (P < .001). Furthermore, both markers showed a significant correlation in their expression in MM and benign reactive MH (r = 77.5, P < .001). Sensitivities of 88% and 92% and specificities of 92% and 94% were obtained at a cutoff point of 9% for Ki-67 and repp86, respectively.
  
  
  CONCLUSIONS
  Used in combination, Ki-67 and repp86 appear to be useful markers in differentiating MM from benign reactive MH.
authors.affiliation: National Research Institute of Tuberculosis and Lung Disease, Department of Pathology, Shahid Beheshti University of Medical Sciences, Tehran, Iran. mtaheri@nritld.ac.ir
authors.forename: Zohreh Mohammad
authors.initials: ZM
authors.lastname: Taheri
authors.forename: Mehdi
authors.initials: M
authors.lastname: Mehrafza
authors.forename: Forozan
authors.initials: F
authors.lastname: Mohammadi
authors.forename: Maliheh
authors.initials: M
authors.lastname: Khoddami
authors.forename: Moslem
authors.initials: M
authors.lastname: Bahadori
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Masjedi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000276:immunology; D015415:Biomarkers / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D049109:Cell Proliferation; D003937:Diagnosis, Differential; D004720:Endonucleases; D004848:Epithelium / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D019394:Ki-67 Antigen / Q000276:immunology / Q000378:metabolism*; D008297:Male; D008654:Mesothelioma / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D018301:Neoplasms, Mesothelial / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins / Q000276:immunology / Q000378:metabolism*; D012680:Sensitivity and Specificity
chemical_list: D000911:Antibodies, Monoclonal; D015415:Biomarkers; D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D009687:Nuclear Proteins; D004720:Endonucleases; C095221:SND1 protein, human