Comparison of Polymerase Chain Reaction, Ziehl-Neelsen Staining and Histopathologic Findings in Formalin-fixed, Paraffin-Embedded Tissue Specimens for Diagnosis of Tuberculosis

Background and objective: tuberculosis is still a major health problem, involving about 1/3 of the world´s population. diagnosis is difficult when we only use ziehl-neelson staining. many cases may be missed. a more rapid and sensitive diagnostic method is necessary. pcr may be helpful. the aim of this study is to compare pcr, zieh-neelsen staining and histopathologic findings in diagnosis of tuberculosis on formalin-fixed paraffin-embedded tissues.methods: paraffin blocks of the submitted specimens of the patients clinically suspicious for tuberculosis or containing granuloma were selected. ziehl-neelsen staining & tb-pcr (is6110 element) were carried out. the results of the tests were compared by using the mcnemar test. statistical significance was accepted when the p value was less than 0.05.results: forty five specimens were included in the study, 35 had granulomas (19 with caseous necrosis). acid-fast bacilli were identified in 17 specimens (37.8%). tb-pcr was positive in 16specimens (84%) with caseating granulomas, 11 specimens (68.8%) with non-caseating granulomas & 6 specimens (60%) without granulomas. (p value = 0.59).conclusions: tb-pcr on paraffin–embedded tissue is a potentially useful approach for early, rapid and sensitive diagnosis of tuberculosis. it is especially useful when granuloma is seen in tissue section, while acid-fast stain is negative. if there was no facilities for pcr, histopathological diagnosis with clinical correlation is more reliable in comparison to afb results.