Figure 3. (a) Bronchoscopy shows widespread ulceration of the tracheobronchial mucosa and a yellow lesion with caseating material adjacent to the opening site of the right main lobe bronchus. A fistula (arrow) extending from the left main bronchus towards the right main bronchus (asterisk) is also seen. (b) Photomicrograph of the bronchial brushing material with acid-fast staining shows Mycobacterium tuberculosis bacilli (arrowheads) (Ziehl–Neelsen stain, x 100).