From the Guidelines
The presence of a tree-in-bud pattern on a Computed Tomography (CT) scan of the lungs is a significant finding that indicates inflammation and filling of the small airways with fluid, mucus, pus, or other material, often associated with infectious bronchiolitis, particularly from bacterial infections like non-tuberculous mycobacterial infections, or other conditions such as cystic fibrosis or allergic bronchopulmonary aspergillosis 1.
Clinical Significance
The tree-in-bud pattern is a radiological finding that resembles a budding tree, with small branching structures visible at the ends of bronchioles. This pattern is commonly associated with:
- Infectious bronchiolitis, particularly from bacterial infections like non-tuberculous mycobacterial infections
- Fungal infections
- Viral bronchiolitis
- Aspiration pneumonia
- Non-infectious conditions like cystic fibrosis or allergic bronchopulmonary aspergillosis
Diagnostic Approach
When this pattern is identified, further diagnostic testing is typically needed to determine the underlying cause, which may include:
- Sputum cultures
- Bronchoscopy with bronchoalveolar lavage
- Blood tests
Treatment
Treatment depends on identifying the specific cause but often involves:
- Antibiotics for bacterial infections
- Antifungals for fungal causes
- Management of underlying conditions The pattern develops because the small airways become impacted with inflammatory material, creating the characteristic branching appearance on imaging that resembles the winter branches of a tree with buds at the tips, as described in the context of non-tuberculous mycobacterial diseases 1.
Key Considerations
- The tree-in-bud pattern can be associated with a range of conditions, and a comprehensive diagnostic approach is necessary to determine the underlying cause.
- The presence of this pattern on a CT scan can have significant implications for patient management and treatment, as highlighted in guidelines for the diagnosis and treatment of non-tuberculous mycobacterial diseases 1.
From the Research
Tree-in-Bud Pattern Significance
The tree-in-bud pattern on Computed Tomography (CT) scans of the lungs is a significant radiologic finding that can indicate various conditions. Some of the key points about this pattern include:
- The tree-in-bud pattern consists of small centrilobular nodules of soft-tissue attenuation connected to multiple branching linear structures of similar caliber that originate from a single stalk 2.
- This pattern is commonly associated with peripheral airway diseases, including infections, congenital disorders, idiopathic disorders, aspiration or inhalation of foreign substances, immunologic disorders, and connective tissue disorders 2.
- The tree-in-bud pattern can also be seen in patients with peripheral pulmonary vascular diseases, such as neoplastic pulmonary emboli 2.
- In addition to infectious causes, the tree-in-bud pattern can be caused by other factors, such as chronic abuse of inhaled cocaine 3.
- The microbiologic significance of the tree-in-bud pattern has been evaluated, and it has been found that the majority of cases have an infectious etiology, with a smaller percentage having aspiration pneumonia or other causes 4.
- The tree-in-bud pattern can be automatically detected using computer-assisted detection (CAD) methods, which can assist in the clinical and research investigation of pulmonary infections 5.
- The frequency and significance of the tree-in-bud pattern on thin-section CT have been described, and it has been found that this pattern is mostly associated with pulmonary infections that commonly involve the large airways 6.
Causes of Tree-in-Bud Pattern
Some of the causes of the tree-in-bud pattern include:
- Infections, such as bacterial, fungal, viral, or parasitic infections 2, 4, 6
- Congenital disorders 2
- Idiopathic disorders, such as obliterative bronchiolitis or panbronchiolitis 2
- Aspiration or inhalation of foreign substances 2, 3, 6
- Immunologic disorders 2
- Connective tissue disorders 2
- Peripheral pulmonary vascular diseases, such as neoplastic pulmonary emboli 2
- Chronic abuse of inhaled cocaine 3
Diagnostic Considerations
The tree-in-bud pattern on CT scans of the lungs can be useful in suggesting the appropriate diagnosis, especially when combined with additional radiologic findings, history, and clinical presentation 2, 4, 6. However, the causes of this pattern are frequently indistinguishable at radiologic evaluation, and further investigation may be necessary to determine the underlying cause 2, 4.