On plain CT scan, it was found that there was a low density nodule with a diameter of 6mm at the front end of the upper lobe of the left lung, which was round and had a clear boundary.

It can be thought that your lungs are infected with tuberculosis and left behind. The imaging examination of malignant lung masses is usually irregular and unclear. Plus the size of 6MM, the boundary is clear and round, combined with the strong PPD positive two years ago, it may be a tuberculoma. If you have symptoms such as cough, you can rule out the recurrence of tuberculosis; Don't worry too much. If we have to rule out the possibility of malignant pulmonary nodules, it is still a little difficult, because it is too small, I am afraid that puncture biopsy can't be done, and it is not in the hilum, and bronchoscopy can't be done. Other methods for detecting malignant nodules have a low diagnostic rate in theory.