The role of DNA polymerase chain reaction, culture and histopathology in the diagnosis of cutaneous tuberculosis

Background Cutaneous tuberculosis (TB) is re-emerging as a significant problem in India due to increased incidence of human immunodeficiency virus (HIV), acquired immune deficiency syndrome (AIDS), other immunosuppressive states/ factors like drugs, and emergence of multidrug resistance (MDR-TB). Proper diagnosis is warranted as there is varied clinical presentation and similarity with many other diseases. Objective To assess the sensitivities of DNA polymerase chain reaction (PCR), culture, and histopathology for the diagnosis of cutaneous TB in clinically suspected skin lesions. Methods Clinically suspected cases of cutaneous TB were enrolled in the study. Two skin punch biopsies were taken from each patient and sent for histopathology examination and DNA PCR with culture, respectively. Results Of the total 70 cases enrolled, 49 were detected as cutaneous TB by the above tests. The sensitivities of DNA PCR, culture, and histopathology were 24.5, 16.3, and 91.8%, respectively. Conclusion DNA PCR and culture should be advised in cases of cutaneous TB with inconclusive histopathology. DNA PCR should be considered in preference over culture if facilities are available as it gives rapid results and has a higher sensitivity.