Among the causes of the solitary pulmonary nodule (SPN), benign causes including tuberculosis was noted on 15 to 60 percents in various studies.

Although the characteristics of chest imaging is helpful in diagnosis and percutaneous needle biopsy for pulmonary nodule has been represented high diagnostic yield in many reports, but still surgical biopsy has been needed in definite diagnosis of pulmonary nodules in many cases.

The aim of this study is to evaluate the usefulness of interferon-gamma release assay in addition to the percutaneous needle biopsy, in diagnosis of pulmonary nodules.

Among the patients who failed to diagnosis by percutaneous needle biopsy and needed to have Surgical biopsy, thirty percents of the patients were diagnosed as benign nodules and about six percents were diagnosed as tuberculosis in Seoul National University Hospital during 2007-2008.

The investigators want to know whether conducting an interferon-gamma release assay in addition to percutaneous needle biopsy is helpful in diagnosis of lung nodules.

Inclusion Criteria:

• Age> 18 years
• in patients with solitary pulmonary nodule
• who had percutaneous needle biopsy for diagnosis of lung nodule

Exclusion Criteria:

• patients who do not agree the study enrollment

Among the inpatients who got percutaneous needle biopsy for pulmonary nodule during the study periods are going to be enrolled.