Figure 17b. Tuberculous broncholithiasis. (a) Chest radiograph demonstrates partial atelectasis of the right upper lobe (straight arrow) with calcified hilar lymph nodes bilaterally (curved arrows). (b) Axial CT scan demonstrates erosion of the right main bronchus (straight solid arrow) by a calcified hilar lymph node (curved arrow). A calcified precarinal lymph node is also noted (open arrow). The differential diagnosis for mediastinal lymph node calcification includes histoplasmosis, silicosis, and treated lymphoma.