title: Bacteriological methods as add on tests to fine-needle aspiration cytology in diagnosis of tuberculous lymphadenitis: can they reduce the diagnostic dilemma?
abstract: BACKGROUND
  The diagnostic accuracy of fine-needle aspiration (FNA) cytology for the diagnosis of tuberculous lymphadenitis (TBLN) is confounded by mimicking cytomorphologic disorders. The objective of this study was to determine whether supplementing FNA cytology with bacteriological methods improves the overall accuracy of TBLN diagnosis.
  
  
  METHODS
  Two hundred presumptive TBLN cases were included in the study. FNA specimens were collected and examined for cytomorphologic changes, for acid-fast bacilli (AFB) by microscopy and for mycobacterial growth on culture. Culture was done using Lowenstein-Jensen (LJ) medium and mycobacteria growth indicator tube (BACTEC MGIT 960 TB detection system). Differentiation between M. tuberculosis complex (MTBc) and non-tuberculous mycobacteria (NTM) was done by using 500 μg/ml para-nitrobenzoic acid (PNB) susceptibility testing.
  
  
  RESULTS
  Cytomorphology detected TBLN among 80% (160/200) of the presumptive cases. Culture results were available for 188 cases. Twelve samples were excluded due to contamination on both culture methods. Culture confirmed cases accounted for 78% (147/188) of which MTBc constituted 97.3% (143/147). Among presumptive cases, classified by FNA cytology as 'abscess', 11 were culture positive. Microscopy detected 31.3% (46/147) of culture confirmed mycobacterial lymphadenitis of which 11% (4/37) were diagnosed non-suggestive for tuberculosis (TB) by FNA cytology. Compared to culture (LJ & BACTEC MGIT 960) and AFB microscopy as composite gold standard, FNA cytology had a sensitivity of 88.4% and a specificity of 48.8%. The positive predictive value was 86.1% while the negative predictive value was 54.1%. The confirming power and the ROC curve area was 1.73 and 0.69, respectively.
  
  
  CONCLUSIONS
  FNA cytology showed a relatively high sensitivity but a low specificity. Combining bacteriological methods with FNA cytology in an endemic region like Ethiopia improves the overall accuracy of the diagnosis of mycobacterial lymphadenitis, which in turn may lead to better patient management.
authors.affiliation: Department of Medical Laboratory Sciences and Pathology, Jimma University, Jimma, Ethiopia. ketema.abdissa@ju.edu.et.
authors.forename: Ketema
authors.initials: K
authors.lastname: Abdissa
authors.affiliation: Department of Medical Laboratory Sciences and Pathology, Jimma University, Jimma, Ethiopia. mulualemt.tadesse@gmail.com.
authors.forename: Mulualem
authors.initials: M
authors.lastname: Tadesse
authors.affiliation: Department of Medical Laboratory Sciences and Pathology, Jimma University, Jimma, Ethiopia. mesele_bezabih@yahoo.com.
authors.forename: Mesele
authors.initials: M
authors.lastname: Bezabih
authors.affiliation: Department of Medical Laboratory Sciences and Pathology, Jimma University, Jimma, Ethiopia. alemayehub@gmail.com.
authors.forename: Alemayehu
authors.initials: A
authors.lastname: Bekele
authors.affiliation: Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium. lapers@itg.be.
authors.forename: Ludwig
authors.initials: L
authors.lastname: Apers
authors.affiliation: Mycobacteriology Unit, Department of Microbiology, Institute of Tropical Medicine, Antwerp, Belgium. lrigouts@itg.be.
authors.forename: Leen
authors.initials: L
authors.lastname: Rigouts
authors.affiliation: Department of Medical Laboratory Sciences and Pathology, Jimma University, Jimma, Ethiopia. gemeda.abebe@ju.edu.et.
authors.forename: Gemeda
authors.initials: G
authors.lastname: Abebe
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001431:Bacteriological Techniques / Q000379:methods*; D044963:Biopsy, Fine-Needle; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D003470:Culture Media; D003937:Diagnosis, Differential; D005002:Ethiopia / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D014388:Tuberculosis, Lymph Node / Q000382:microbiology* / Q000473:pathology*; D055815:Young Adult
chemical_list: D003470:Culture Media