Technique with Rapid Turnaround Time for Mycobacterial Tuberculosis in Granulomatous Lesions in Tissue Section
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Abstract
Introduction: Tuberculosis (TB) is devastating infectious disease. Patient usually has enlarged lymph nodes (LN). Mycobacterial culture is considered gold standard. Ziehl-Neelsen stain has low sensitivity. New test like immunohistochemistry (IHC) can confirm involvement by MTB and demonstrate antigen immunolocalization. This study attempts to study details of IHC using Anti MTB polyclonal antibody in suspected cases of TB.
Objectives: To compare immunohistochemistry study with AFB culture, ZN stain and Gene Xpert.
Methods: A cross sectional, Observational study was done where H & E slides of 76 tissue sections of granulomatous inflammation were gathered. IHC was performed using anti-MTB polyclonal antibody (Dako Envision FLEX/HRP) and interpretated based on proportion and intensity of staining in epithelioid cells, giant cells and caseous necrosis. Grading score for proportion of staining: 0-(0-4%), 1 (5-25%), 2-(25-50%), 3-(50-100%), intensity: 0-weak, 1-mild, 2-moderate, 3-strong. Total combined score was 18. IHC score ≥5 considered cut off.
Results: Out of 76 cases majority were LN. Out of 76 cases, 63 (82.9%) showed IHC positivity for MTB with 94.6% sensitivity and 30.6% specificity.
Conclusions: IHC has potential to reveal any mycobacterial antigen. Intact cell wall is not prerequisite. It can aid to diagnose granulomatous inflammation of mycobacterial etiology as it requires less time than culture.