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

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.

The usefulness of nested PCR for the detection of M tuberculosis from tuberculous SPN and for the differential diagnosis of SPN was evaluated.

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.

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%).

Nested PCR for the detection of M tuberculosis in fine needle aspirates may be useful in the differential diagnosis of SPNs.