Active Tuberculous Endobronchitis: Computed Tomography Findings and Implications

Abstract

Objective: To describe the pattern of bronchostenosis revealed by computed tomography and virtual bronchoscopy in patients with active tuberculous endobronchitis and associated pulmonary manifestations. Methods: This retrospective study was conducted in Hong Kong, which is an endemic region for tuberculosis, where tuberculous endobronchitis remains a noteworthy clinical entity, with reported frequency of 10 to 40% in patients with active pulmonary tuberculosis. Medical records of a series of 18 patients with active endobronchial tuberculosis (without acquired immunodeficiency syndrome), having acid-fast bacilli in sputum smears, underwent computed tomography and virtual bronchoscopy in two regional hospitals between January 2007 and October 2009 were reviewed. The location, morphology, length, and percentage of luminal bronchostenotic narrowing were evaluated by such imaging and compared with fibre-optic bronchoscopy findings. Associated parenchymal manifestations, namely tree-in-bud nodules, cavitary lesions, segmental atelectasis and enlarged mediastinal lymph nodes, were assessed. Results: Involvement of tuberculous endobronchitis at a single major lobar bronchus with contiguous spread along ipsilateral bronchial tree was observed in most patients (n = 16, 89%). A mural cause of bronchostenosis remained the most frequent finding (n = 12, 67%), with irregular circumferential thickening predominating (n = 8, 44%). Regarding associated parenchymal manifestations, tree-in-bud nodules occurred in all patients (n = 18, 100%); cavitary lesions (n = 9, 50%) and segmental atelectasis (n = 7, 39%) were less frequent. Mediastinal lymph node enlargement was a rare finding (n = 3, 17%). Fibre-optic bronchoscopy performed during the same admission showed confirmatory results in all available cases (n = 14). Conclusion: Centripetal spread of tuberculous endobronchitis from distal small airways to proximal central airway was observed in the majority of our patients. This could correlate with probable pathogenic mechanisms including the submucosal lymphatic spread of tuberculous bacilli and the implantation of bacilli by infected sputum along the bronchial tree. Relative left-sided predominance of bronchial involvement was observed, possibly related to intrinsic anatomical difference in lymphatic drainage between left-and right-sided bronchi. Irregular circumferential and eccentric mural thickening was the most common morphological pattern of bronchostenosis with mural thickening. Mediastinal lymph node enlargement was rare.