Combined Use of Cytopathological diagnosis with molecular tests performed on concentrated Fine Needle Aspirate samples to improve the lab diagnosis for Tuberculous lymphadenitis suspected patients
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Date
2021-09
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Addis Abeba University
Abstract
Background: Tuberculosis lymphadenitis (TBLN) is a granulomatous infection of lymph nodes
and the most frequent form of extra pulmonary Tuberculosis in Ethiopia. Issues arising in the
cytopathological diagnosis of TBLN suspected patients include the inconclusive result and lack
of easily accessible diagnostic tests. In both instances, considerable consequences are observed
concerning clinical management, economical perspective, and time. The fate of TBLN suspected
patients with an inconclusive cytopathological result will be either taking other antibiotics or be
on anti-TB treatment empirically. Though both approaches are targeted towards the benefit of the
patient, they may either lead to inappropriate treatment outcome or cause the patient to suffer
more from the disease. This is mainly resulted in due to lack of concrete affirmative laboratory
diagnostic tools that support the cytopathological diagnostic method.
Objective: To investigate the combined use of cytopathological diagnosis with molecular tests
performed on concentrated FNA sample in the detection of TBLN cases.
Methods: A cross sectional study was conducted at ALERT Hospital and the Lab work was
performed at AHRI, Addis Ababa from Sept 2020 – April 2021. Using consecutive sampling
technique, 96 participants suspected of having TBLN were enrolled in this study. The sensitivity,
specificity, positive and negative predictive values including their 95% confidence intervals (CI)
was calculated by using the culture results as the "gold standard". Cohen’s Kappa value was used
to measure interrater variability and level of agreement. All statistical tests were considered
significant when having a two-sided P-value of <0.05.
Result: Out of the 96 participant, ZN, AO, Cytopathology, Xpert, RT PCR and LJ culture
prevailed 12 (12.5%), 27 (28.1%), 51 (53.1%), 43 (44.7%), 51 (53.1%), 36 (37.5%) positive
result respectively. The sensitivity of Xpert, RT PCR, and FNAC were 91.7%, 97.2%, and
97.2%, and the specificity were 83.3%, 73.3%, and 68.3% respectively. GeneXpert and RT PCR
when combined with Cytology detected 61 (63.5%) positive and culture being gold standard, the
sensitivity reached 100% while the specificity drops to 58.3%.
Conclusion: Combination of molecular test, performed on concentrated sample, with
cytopathology shown increased sensitivity, particularly geneXpert with FNAC provides an
elevating alternative in case detection rate of Tubercular lymphadenitis patients with improved specificity. It also provides affirmative results and hence aid in alleviating issues with
inconclusive results.
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Keywords
Tuberculous Lymphadenitis, RT PCR, Concentration technique, Cytopathology GeneXpert.