Tree-in-bud sign

A radiological sign indicating certain lung conditions

The tree-in-bud sign is a radiological pattern 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 within the small airways and is often associated with infectious and non-infectious conditions.

Radiological Appearance

On HRCT, the tree-in-bud sign appears as small, centrilobular nodules connected by linear branching opacities. These opacities represent dilated and impacted bronchioles filled with mucus, pus, or other material. The pattern is typically seen in the peripheral regions of the lung and is best visualized on thin-section CT scans.

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 or nontuberculous mycobacterial infection.
• Aspiration pneumonia: Resulting from the inhalation of foreign material into the lungs.
• Cystic fibrosis: A genetic disorder that affects the lungs and other organs.
• Primary ciliary dyskinesia: A rare genetic disorder that affects the cilia, leading to chronic respiratory tract infections.

Diagnosis

The diagnosis of conditions associated with the tree-in-bud sign involves a combination of clinical evaluation, imaging studies, and sometimes laboratory tests or biopsy. The presence of the tree-in-bud pattern on HRCT can guide clinicians towards specific diagnoses, but it must be interpreted in the context of the patient's clinical presentation and history.

Management

Treatment of the underlying cause of the tree-in-bud sign is essential. For infectious causes, appropriate antibiotic therapy is required. In cases of chronic conditions like cystic fibrosis or primary ciliary dyskinesia, management focuses on controlling symptoms and preventing complications.

Prognosis

The prognosis for patients with a tree-in-bud sign depends on the underlying condition. Infectious causes may resolve with treatment, while chronic conditions may require long-term management.

Related pages

• Bronchiolitis
• High-resolution computed tomography
• Pulmonary infection

External links

• Tree-in-bud sign on Radiopaedia

HRCT scan showing tree-in-bud pattern in a patient with primary ciliary dyskinesia.