Tree-in-bud pattern – Pulmonary TB

Clinical History

A 53-year-old African male was referred to our institution with non-resectable oesophageal squamous cell carcinoma - diagnosed 3 months before - for radiotherapy. He developed onset symptoms of dysphagia and weight-loss when endoscopic procedure with biopsy confirmed the diagnosis. Laboratory tests revealed anaemia (Hg=9, 6g/L), low albumin and elevated PCR.

Imaging Findings

CT-scout-view showed opacity of the right upper lobe associated with bronchiectasis resembling necrotic pneumonia. No pleural effusion or large lymph node involvement was depicted.
CT/HRCT (high-resolution-CT) showed extensive bronchiectasis along with parenchymal disruption in the right upper lobe. The remaining pulmonary parenchyma demonstrated scattered tree-in-bud pattern with lower lobe predominance and without pleural effusion. The patient had an oesophageal lesion below the carina extending longitudinally 6 cm. There are no criteria for invasion of the aorta or the bronchial tree. Lymph node involvement at the carina level were noted.
Patient underwent bronchoscopy and cough sputum sample was sent to bacteriological analysis with subsequent confirmation of positive Koch's bacilus specimen on direct examination.

Discussion

The World Health Organization (WHO) estimates that 2 billion people have latent TB and that globally in 2009 it killed 1.7 million people. Active pulmonary TB may present as asymptomatic, mild to progressive dry cough or cough with bloody sputum often accompanied by fever, weight loss, and night sweats. A definitive diagnosis based on bacteriological culture remains challenging because M. tuberculosis is a slow-growing microorganism [1, 2, 4].
Primary tuberculosis can manifest as four main entities: parenchymal disease, lymphadenopathy, miliary disease and pleural effusion. The earliest finding in parenchymal disease is patchy, poorly-defined consolidation, particularly in the apical and posterior segments of the upper lobes. Furthermore, bilateral disease can be seen in one third to two thirds of cases [1].
Postprimary tuberculosis usually refers to both reinfection and reactivation of tuberculosis. Primary tuberculosis is usually self-limiting, whereas postprimary tuberculosis is progressive. Cavitation is the hallmark, resulting in hematogenous dissemination and spread throughout the lungs. The cavities are usually multiple and occur within consolidation areas, typically with thick, irregular walls, which become smoother and thinner after successful treatment [2].
Lymphadenopathy and pneumothoraces are less often seen as in this case lymph node involvement was more related with the oesophageal tumour [1].
Our patient presented without pleural effusion or lymphadenopathy. CT showed predominantly airway disease with endobronchial spread of infection, namely tree-in-bud opacities. These findings usually noted in the lung periphery resemble a branching-tree with buds at the tips of the branches, in this case highly suggestive of active tuberculosis [3]. Although there was clinical uncertainty of previous TB-infection, the patient might have previously contacted with M. tuberculosis and subsequently resolved the infection, or hosted the microorganism without typical healing fibrosis or calcification but with pulmonary parenchymal distortion of the right upper lobe that predisposed the extensive bronchiectasis.
Primary and postprimary tuberculosis somehow overlap; the distinguishing features of postprimary tuberculosis include a predilection for the upper lobes, cavitation and absence of lymphadenopathy.
Normal radiographic findings may be seen in up to 15% of patients with proved tuberculosis or show only mild or nonspecific findings in patients with active disease.
CT provides accurate diagnosis in pulmonary TB in 91% of patients and correctly excludes it in 76% of patients [4]. CT/HRCT are particularly helpful in the detection of small foci of cavitation, tree-in-bud pattern and in pleural evaluation, namely tuberculous effusion, empyema, and bronchopleural fistula.

Differential Diagnosis List

Final Diagnosis

Pulmonary tuberculosis

URL:	https://eurorad.org/case/9825
DOI:	10.1594/EURORAD/CASE.9825
ISSN:	1563-4086