Fig. 2

Representative CT images showing incipient TB progressing into active tuberculosis disease in a 52-year-old healthy male. a A screening CT image shows a small single incidental nodule in the right upper lobe (black arrow). b A follow-up CT image 20 months later reveals a few additional micronodules (black arrowheads) in a secondary pulmonary lobule around the small pre-existing nodule (black arrow). The patient denied any symptoms and signs and had negative sputum smear and culture tests. c The next follow-up CT image 24 months later shows the increasing size and number of the nodule (black arrow) and micronodules (black arrowheads) in the right upper lobe. The patient still denied any symptoms and signs. The sputum smear was negative, and Mycobacterium tuberculosis was confirmed on sputum culture. The patient had a 6-month standard anti-tuberculosis medication and healed without sequelae