Endobronchial Tuberculosis

Case history: A 67-year-old female with a history of long standing goiter presented with a short onset history of cough and breathlessness. She did not have any fever or hemoptysis. The chest X-ray was unremarkable.

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Figure 1: Contrast enhanced CT of the chest (Fig 1) revealed irregular concentric wall thickening and luminal narrowing of the distal left main bronchus till the lobar bifurcation. Multiple, clustered subcentimetric mediastinal nodes were also present.

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Figure 2: The entire left lung was hyperlucent, consistent with air trapping, but no parenchymal infiltrates were seen (Fig 2). There was no associated pleural pathology. An incidental multinodular goiter with early retrosternal extension was also noted.

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Figure 3: Since CT findings were highly suspicious for bronchial malignanacy, bronchocopy and bronchoscopic biopsy was performed. Bronchoscopy (Fig 3) revealed severe narrowing of the distal left main bronchus with associated mucosal nodularity.

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Figure 4: Brochoscopic biopsy (Fig 4) demonstrated presence of granulomas containing multiple epitheloid cells and central caseous necrosis. (Hematoxylin and eosin, 10x magnification.)

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Figure 5: The patient was started on antituberculous treatment with four drugs. A review CT chest performed after 2 months (Fig 5) showed significant resolution of the bronchial wall thickening with normalization of the lumen. The lucency of the left lung had also become normal. The mediastinal nodes were persisting.

Diagnosis: Endobronchial tuberculosis

Discussion: Endobronchial tuberculosis (EBTB) is defined as tuberculous infection of the tracheobronchial tree with microbial and/or histopathological evidence. EBTB may occur through one or more of numerous proposed routes: implantation from an adjacent parenchymal focus; intrabronchial rupture of a node; infected sputum; lymphatic or hematogenous spread. EBTB is a highly infectious and the diagnosis is often missed or delayed due to absent or minimal X-ray findings and a low pick up rate from sputum or bronchial lavage fluid.

CT findings in EBTB are varied. There may be isolated segmental bronchial narrowing with concentric wall thickening as in the above case (41- 43%); complete endobronchial obstruction (32%) and extrinsic obstruction from adjacent adenopathy (23 - 50%). Air trapping in a segment or lobe may draw attention to the bronchial abnormality which could otherwise have been overlooked. The presence of associated linear and branching opacities (tree in bud” appearance) is typical of peripheral endobronchial spread of tuberculosis. The tree in bud appearance is a result of dilation and luminal impaction of the peripheral bronchioles with mucus, pus, or fluid along with wall thickening and peribronchiolar inflammation. In the absence of these tree in bud opacities, isolated bronchial wall thickening with luminal narrowing/occlusion may be mistaken for bronchial carcinoma. Other conditions which may mimic EBTB are non specific inflammation, sarcoidosis, endobronchial actinomycosis. Endobronchial Kaposi's sarcoma is also a possibility in AIDS patients.

The aim of this case study is to highlight an uncommon cause of bronchial wall thickening and emphasise that all cases of bronchial wall thickening are not carcinomas. A high index of suspicion, timely CT scan and bronchoscopic biopsy can result in early diagnosis and treatment of EBTB. CT is the modality of choice for diagnosis, assessment of extent of bronchial involvement, guidance for bronchoscopic biopsies and evaluation of delayed complications like bronchial stenosis, bronchiectasis or broncholiths.

References:
1. Kashyap S, Mohapatra PR and Saini V. Review Article- Endobronchial Tuberculosis. Indian J Chest Dis Allied Sci 2003; 45 : 247-256
2. Gupta PP, Agarwal D, Gupta KB, Sood S. CT evaluation in diagnosis of endobronchial tuberculosis. Lung India 2006; 23:126-12992.
3. Tetikkurt C. Current perspectives on endobronchial tuberculosis. Pneumon 2008; 21(3):239 –245
4. Qingliang X and Jianxin W. Investigation of endobronchial tuberculosis - diagnoses in 22 cases. European Journal of Medical Research 2010; 15:309-313.

Arti Chaturvedi, MD
Senior Consultant, Department of Radiodiagnosis
Fortis International Hospital, Noida, India