Tree in bud sign

Radiological sign indicating certain lung conditions

Tree-in-bud sign
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Synonyms	N/A
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Specialty	N/A
Symptoms
Complications
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Causes	Infection, bronchiolitis, aspiration
Risks
Diagnosis	Computed tomography (CT) scan
Differential diagnosis
Prevention	N/A
Treatment
Medication	N/A
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The tree-in-bud sign is a radiological finding seen on high-resolution computed tomography (HRCT) scans of the lungs. It is characterized by small centrilobular nodules and branching linear structures that resemble a budding tree. This sign is indicative of certain pathological processes affecting the small airways and is often associated with infectious and inflammatory conditions.

Pathophysiology

The tree-in-bud sign represents the presence of material, such as mucus, pus, or fluid, within the small airways, particularly the bronchioles. This material causes the bronchioles to become dilated and filled, leading to the characteristic appearance on CT scans. The branching pattern is due to the involvement of the terminal bronchioles and the surrounding alveolar ducts.

Causes

The tree-in-bud sign can be caused by a variety of conditions, including:

• Infectious bronchiolitis: Often due to bacterial infections such as tuberculosis, nontuberculous mycobacterial infection, or bacterial pneumonia.
• Aspiration pneumonia: Occurs when foreign material, such as food or gastric contents, is inhaled into the lungs.
• Cystic fibrosis: A genetic disorder that leads to the production of thick, sticky mucus that can block the airways.
• Bronchiectasis: A condition characterized by permanent dilation of the bronchi, often due to chronic infection or inflammation.

Diagnosis

The tree-in-bud sign is primarily diagnosed through imaging studies, particularly high-resolution CT scans of the chest. On the CT scan, the sign appears as small, centrilobular nodules with a branching pattern, typically in the peripheral regions of the lung.

Clinical Significance

The presence of a tree-in-bud sign on a CT scan can help narrow down the differential diagnosis for a patient presenting with respiratory symptoms. It suggests the presence of small airway disease and can guide further diagnostic testing and management.

Management

Management of conditions associated with the tree-in-bud sign depends on the underlying cause. For infectious causes, appropriate antibiotic or antiviral therapy is indicated. In cases of aspiration, addressing the underlying risk factors and providing supportive care is essential.

Also see

• Bronchiolitis
• Pulmonary tuberculosis
• Aspiration pneumonia
• Cystic fibrosis
• Bronchiectasis