title: The use of light-emitting diode fluorescence to diagnose mycobacterial lymphadenitis in fine-needle aspirates from children.
abstract: BACKGROUND
  Fine-needle aspiration biopsy (FNAB) is a simple, safe and effective method for investigating suspected mycobacterial lymphadenitis in children. Fluorescence microscopy can provide rapid mycobacterial confirmation. Light-emitting diodes (LEDs) provide a cheap and robust excitation light source, making fluorescence microscopy feasible in resource-limited settings.
  
  
  OBJECTIVE
  To compare the diagnostic performance of LED fluorescence microscopy on Papanicolaou (PAP) stained smears with the conventional mercury vapour lamp (MVL).
  
  
  METHODS
  FNAB smears routinely collected from palpable lymph nodes in children with suspected mycobacterial disease were PAP-stained and evaluated by two independent microscopists using different excitatory light sources (MVL and LED). Mycobacterial culture results provided the reference standard. A manually rechargeable battery-powered LED power source was evaluated in a random subset.
  
  
  RESULTS
  We evaluated 182 FNAB smears from 121 children (median age 31 months, interquartile range 10-67). Mycobacterial cultures were positive in 84 of 121 (69%) children. The mean sensitivity with LED (mains-powered), LED (rechargeable battery-powered) and MVL was respectively 48.2%, 50.0% and 51.8% (specificity 78.4%, 86.7% and 78.4%). Inter-observer variation was similar for LED and MVL (κ = 0.5).
  
  
  CONCLUSIONS
  LED fluorescence microscopy provides a reliable alternative to conventional methods and has many favourable attributes that would facilitate improved, decentralised diagnostic services.
authors.affiliation: Division of Anatomical Pathology, Department of Pathology, National Health Laboratory Service, Stellenbosch University, Cape Town, South Africa. avw@sun.ac.za
authors.forename: A C
authors.initials: AC
authors.lastname: van Wyk
authors.forename: B J
authors.initials: BJ
authors.lastname: Marais
authors.forename: R M
authors.initials: RM
authors.lastname: Warren
authors.forename: S S
authors.initials: SS
authors.lastname: van Wyk
authors.forename: C A
authors.initials: CA
authors.lastname: Wright
mesh_terms: D000293:Adolescent; D044963:Biopsy, Fine-Needle; D002648:Child; D002675:Child, Preschool; D011211:Electric Power Supplies; D004867:Equipment Design; D005260:Female; D017048:Health Care Costs; D006801:Humans; D007223:Infant; D008198:Lymph Nodes / Q000382:microbiology*; D008199:Lymphadenitis / Q000175:diagnosis* / Q000382:microbiology; D008297:Male; D008856:Microscopy, Fluorescence / Q000191:economics / Q000295:instrumentation; D009161:Mycobacterium / Q000302:isolation & purification*; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013019:South Africa; D013194:Staining and Labeling; D014388:Tuberculosis, Lymph Node / Q000175:diagnosis* / Q000382:microbiology