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 thecytopathological diagnosis of TBLN suspected patients include the inconclusive result and lackof easily accessible diagnostic tests. In both instances, considerable consequences are observedconcerning clinical management, economical perspective, and time. The fate of TBLN suspectedpatients with an inconclusive cytopathological result will be either taking other antibiotics or beon anti-TB treatment empirically. Though both approaches are targeted towards the benefit of thepatient, they may either lead to inappropriate treatment outcome or cause the patient to suffermore from the disease. This is mainly resulted in due to lack of concrete affirmative laboratorydiagnostic tools that support the cytopathological diagnostic method.
Objective: To investigate the combined use of cytopathological diagnosis with molecular testsperformed on concentrated FNA sample in the detection of TBLN cases.
Methods: A cross sectional study was conducted at ALERT Hospital and the Lab work wasperformed at AHRI, Addis Ababa from Sept 2020 – April 2021. Using consecutive samplingtechnique, 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 usedto measure interrater variability and level of agreement. All statistical tests were consideredsignificant when having a two-sided P-value of <0.05.
Result: Out of the 96 participant, ZN, AO, Cytopathology, Xpert, RT PCR and LJ cultureprevailed 12 (12.5%), 27 (28.1%), 51 (53.1%), 43 (44.7%), 51 (53.1%), 36 (37.5%) positiveresult respectively. The sensitivity of Xpert, RT PCR, and FNAC were 91.7%, 97.2%, and97.2%, and the specificity were 83.3%, 73.3%, and 68.3% respectively. GeneXpert and RT PCRwhen combined with Cytology detected 61 (63.5%) positive and culture being gold standard, thesensitivity reached 100% while the specificity drops to 58.3%.
Conclusion: Combination of molecular test, performed on concentrated sample, withcytopathology shown increased sensitivity, particularly geneXpert with FNAC provides anelevating alternative in case detection rate of Tubercular lymphadenitis patients with improved specificity. It also providesaffirmative results and hence aid in alleviating issues withinconclusive results.
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Keywords
Tuberculous Lymphadenitis, RT PCR, Concentration technique, Cytopathology GeneXpert.