title: The predictive value of Gen-Probe's amplified Mycobacterium tuberculosis direct test compared with culturing in paraffin-embedded lymph node tissue exhibiting granulomatous inflammation and negative acid fast stain.
abstract: OBJECTIVE
  The diagnosis of granulomatous inflammation with possible tuberculosis (TB) infection in histopathology is often difficult. There is a need for a rapid and reliable diagnostic test. Thus, we evaluated the performance of the Mycobacterium tuberculosis direct (MTD) test in specimens with granulomatous lymphadenitis and negative acid fast stains.
  
  
  METHODS
  The M. tuberculosis direct (MTD) test by Gen-Probe was performed on 45 formalin-fixed paraffin-embedded tissue samples including 34 lymph nodes. We measured the predictive values of the MTD test in specimens with granulomatous lymphadenitis and negative acid fast stains.
  
  
  RESULTS
  The overall test sensitivity was 73.9%, and specificity was 95.4%. The MTD test sensitivity and specificity for lymph node tissue were 72.7% and 91.67%, respectively. In the presence of granulomatous inflammation, the MTD test sensitivity and specificity were higher than those for all tissue samples, at 75% and 100%, respectively.
  
  
  CONCLUSIONS
  Based on this study, the MTD test should be used as a supportive test in addition to conventional histochemical or immunological staining methods when evaluating lymph node tissue with a granulomatous inflammation to deliver stronger evidence to support clinical decisions at a much earlier time than a culture would allow.
authors.affiliation: Pathology Services Division, Dhahran Health Center, Saudi Aramco Medical Services Organization, Dhahran, Saudi Arabia. Electronic address: wasim.raslan@aramco.com.
authors.forename: Wasim F
authors.initials: WF
authors.lastname: Raslan
authors.affiliation: Pathology Services Division, Dhahran Health Center, Saudi Aramco Medical Services Organization, Dhahran, Saudi Arabia.
authors.forename: Ali
authors.initials: A
authors.lastname: Rabaan
authors.affiliation: Specialty Internal Medicine Unit, Dhahran Health Center, Saudi Aramco Medical Services Organization, Dhahran, Saudi Arabia.
authors.forename: Jaffar A
authors.initials: JA
authors.lastname: Al-Tawfiq
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D010336:Pathology / Q000379:methods*; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013194:Staining and Labeling / Q000379:methods; D014388:Tuberculosis, Lymph Node / Q000175:diagnosis*
keywords: Gen-Probe; Granuloma; Molecular testing; Mycobacterium tuberculosis direct (MTD) test; Tuberculosis