The use of light-emitting diode fluorescence to diagnose mycobacterial lymphadenitis in fine-needle aspirates fromchildren
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).
CONCLUSION: LED fluorescence microscopy provides a reliable alternative to conventional methods and has many favourable attributes that would facilitate improved, decentralised diagnostic services.
Document Type: Regular Paper
Affiliations: 1: Division of Anatomical Pathology, Department of Pathology, National Health Laboratory Service, Stellenbosch University, Cape Town, South Africa 2: Department of Paediatrics and Child Health, Stellenbosch University, Cape Town, South Africa 3: Division of Molecular Biology and Human Genetics, Stellenbosch University, Cape Town, South Africa 4: Desmond Tutu TB Centre, Department of Paediatrics and Child Health, Stellenbosch University, Cape Town, South Africa
Publication date: January 1, 2011
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