Diagnostic Utility of ZN, IH and PCR in Detection of Tuberculous Lymphadenopathy: A Retrospective Study from Sudan

Background: Lymph node tuberculosis (LNTB) is the leading cause of extra pulmonary tuberculosis and is the most frequently identified type in Khartoum state, Sudan. Conventional diagnosis has serious limitations for rapid detection of LNTB in clinical samples. Therefore, the aim of this study was to assess the diagnostic utility of IH and ZN, since they are the routine used methods. Methodology: Out of 718 lymphadenopathy specimens, 161/718 (22.4 %) lymph nodes tissue biopsies that were previously diagnosed by conventional histopathology as having tuberculosis were reinvestigated. The specific monoclonal anti 38KD was used to detect MTB by IHC, and IS6110 sequence for MTB was used to perform PCR. IS6110 PCR assay was performed in comparison with the histopathology diagnosis, Z. N stain and IHC. Results: ZN stain was positive in 4/161 (2.5 %) of the cases, since, PCR and IHC were positive in 135/161 (83.85 %) and 129/161 (80.12 %) of the cases respectively. Conclusions: IHC and PCR have high sensitivity in detection of lymph node associated MBT. It advisable to use these techniques before reporting the negative results.