Nested polymerase chain reaction for detection of Mycobacterium tuberculosis in solitary pulmonary nodules

Background: Differential diagnosis of solitary pulmonary nodules (SPNs) can be difficult in areas, such as Korea, where tuberculosis is endemic. Nested polymerase chain reaction (PCR) is a widely used method to test a very small amount of pathogen and to detect Mycobacterium tuberculosis from fine needle aspirates. Objectives: The usefulness of nested PCR for the detection of M tuberculosis from tuberculous SPN and for the differential diagnosis of SPN was evaluated. Methods: Thirty-three patients in whom a diagnosis of SPN was made based on a CT scan of the chest were enrolled in this study. Included were 17 malignant and 16 benign SPNs. Nested PCR was carried out for the detection of M tuberculosis by using TB-1, TB-2, TB-28, and TB-29C on fine needle aspirates from the nodule in all 33 cases. Results: Aspirates from malignant neoplasms, pneumonia, and sequestration were all negative on nested PCR for tuberculosis. One of the three radiologically suspected tuberculous nodules without response to anti-tuberculosis drugs (uncertain) yielded positive results on nested PCR for the detection of M tuberculosis. In contrast, 7 out of 8 (87.5%) aspirates from proven tuberculous nodules showed positive results on nested PCR. Nested PCR could be used to detect M tuberculosis in fine needle aspirates from tuberculous SPNs with good sensitivity (87.5%) and specificity (96.0%). Conclusion: Nested PCR for the detection of M tuberculosis in fine needle aspirates may be useful in the differential diagnosis of SPNs.