The onset of EBTB may be acute, insidious, or delayed.
Awareness of the entity and consideration of EBTB as differential diagnosis in confusing cases might be helpful for clinicians in planning further strategy for definitive diagnosis.
Bacteriologic confirmation should be the first step for confirmation of diagnosis of EBTB. Freshly expectorated sputum is considered the best sample for microscopy.
In view of low positivity rate of acid fast bacilli detection by sputum microscopy in EBTB, other diagnostic methods may be beneficial to reach a diagnosis of tuberculosis in confusing scenario.
The dominant pattern in EBTB is usually restrictive (47%), followed by normal pulmonary function, mixed pattern, and obstructive pattern .
On the basis of bronchoscopic findings EBTB is usually classified into seven subtypes with specific appearance: (i) actively caseating--swollen hyperemic bronchial mucosa covered with whitish cheese-like material, (ii) edematous-hyperemic--extensive mucosal swelling with surrounding hyperemia, (iii) fibrostenotic--marked narrowing of the bronchial lumen with fibrosis, (iv) tumorous--endobronchial mass with surface covered by caseous material and nearly totally occluding the bronchial lumen (Figure 3), (v) granular--appearance like scattered grains of boiled rice, (vi) ulcerative--ulcerated bronchial mucosa, and (vii) nonspecific bronchitis--only mild mucosal swelling and/or hyperemia .
This classification of EBTB is closely related to the extent of disease progression.
The highest positivity for acid fast bacilli (AFB) as well as mycobacterial culture in bronchial lavage fluid has been reported in the granular type of EBTB (75%) and the least in fibrostenotic stage indicating significance of microbiologic methods restricted for early lesions.
Tumorous EBTB can also develop by erosion of an intrathoracic tuberculous lymph node into the bronchus.
The prognosis of actively caseating type and edematous-hyperemic type EBTB is worst, resulting in fibrostenosis in two-thirds of patients.
All subtypes of EBTB are situated between the extreme ends of healing and bronchostenosis and can transform into other subtypes during treatment.