Concordance of Cytomorphological Features of Cervical Lymphadenitis Suspected for Mycobacterium Tuberculosis on Fine Needle Aspiration Biopsy with GeneXpert for Mycobacterium Tuberculosis on Aspirated Material

Abstract

Objective: The objective of the study was to correlate different cytomorphological presentations of cervical lymphadenitis suspected for Mycobacterium Tuberculosis (MTB) on Fine Needle Aspiration Cytology (FNAC) with MTB detection by geneXpert on aspirated material.Study Design: Comparative, cross sectional study.Place and Duration of Study: Department of Histopathology, Armed Forces Institute of Pathology (AFIP), Rawalpindi, Pakistan, from January 2017 through November 2018.Methodology: Fine needle aspirates of total 100 patients with cervical lymphadenitis suspected for MTB were included in the study and the cytology was compared with geneXpert, keeping geneXpert as gold standard. After obtaining FNA aspirates from cervical lymph nodes, the smears were evaluated for various patterns of granulomatous inflammation. The aspirate was sent to the microbiology department for confirmation of presence of MTB by PCR (geneXpert), results of which were then compared. Data was analyzed using SPSS version 23. Descriptive statistics, frequencies and percentages were calculated.Results: A total of 100 samples of cervical lymphadenitis, in which MTB was suspected, were evaluated out of which 53 were males and 47 were females. The male to female ratio was 1.12:1. Mean age of population in study was 31 ± 15 years. Minimum age at presentation was 4 years and maximum age was 72 years. Maximum incidence of disease was seen in young patients between 15 and 40 years. On FNAC smears, a total of 61% (n=61) cases showed granulomas with caseous necrosis, 14% (n=14) cases showed abscess only, 10% cases (n=10) showed granulomas only, 10% (n=10) cases showed granulomas with abscess while 5% (n=5) cases showed caseous necrosis only. A total of 78 cases were positive for MTB while 22 cases were negative when compared with molecular analysis on aspirated material. Positivity for MTB by geneXpert was seen in 93% (n=57) cases with both caseous necrosis and granulomas, 80% (n=4) cases with caseous necrosis only, 80% (n=10) cases having granulomas along with neutrophilic abscess, 70% (n=7) cases showing only granulomas and 14% (n=2) cases with neutrophilic abscess only (p value<0.05). The sensitivity of FNAC was 97% and specificity was 54.Positive predictive value (PPV) was 88% and Negative predictive value (NPV) was 85%.Conclusion: MTB was detected by GeneXpert in a significant percentage of the FNAC samples included in our study. FNAC is a rapid, safe, inexpensive, easily available, minimally invasive, outpatient procedure and GeneXpert can be performed on the aspirated material for the diagnosis of cervical lymphadenitis suspected for MTB infection. This can aid the clinicians in timely initiation of Anti Tuberculous Treatment (ATT) in our country where tuberculosis is rampant and advanced diagnostic facilities are not easily accessible.