Accuracy Detection of Mycobacterium Tuberculosis DNA,using Polymerase Chain Reaction by Granulomatous Lesion in Tissue Section

ABSTRACT

Objective: to correlation the relationships of histopathology presenting of granuloma with TB-PCR method and calculated the sensitivity and specificity. Materials and Methods: Descriptive retrospectively study, selected 209 patients, during 2007-2008 at King Chulalongkorn Memorial Hospital, who were clinically suspected to have tuberculosis and had a history of previously tissue sampling from various organs for light microscopic examination. Two pathologists reviewed their histopathological features independently again. The presence and absence of granulomatous formation was assessed. All of these tissues were analysed by using the positive results of TB-PCRResults: 97 cases (46%) had microscopically granulomatous formation and the other 112 cases (54%) were diagnosed as chronic inflammation without granulomas. In the former 97 patients with chronic granulomatous inflammation, 24 cases (25%) were TB-PCR positive and 73 cases (75%) were TB-PCR negative. Whereas the results of 112 patients having only chronic inflammation, 27 cases (24%) were positive for TB-PCR and the remaining 85 cases (76%) were negative. Collected data, including presence or absence of granulomas, results of TB-PCR and acid fast stain was evaluated their relationships and calculated the sensitivity and specificity of granulomatous cases (75%) were TB-PCR negative. Whereas the results of 112 patients having only chronic inflammation, 27 cases (24%) were positive and the remaining 85 cases (76%) were negative. Base on definite results of TB-PCR, granulomatous formation had a sensitivity of 47% (24/51) and a specificity of 54% (85/158). The positive predictive value for granulomas was 25% (24/97) and its negative predictive value was 76% (85/112).Conclusion: Granulomators formation is not a sensitive method for investigate Mycobacterium tuberculosis in paraffinembedded tissue, probably in small pieces of specimens or immunocompromised patients that granulomas are rarely formed.