How to diagnose the causes of tree-in-bud pattern in the lungs

In general, the cause of tree-in-bud sign in the lungs can be diagnosed through methods such as imaging features, clinical symptoms, medical history, laboratory tests, and response to treatment. The specific analysis is as follows:

1. Imaging Features

If CT shows a tree-in-bud pattern accompanied by centrilobular nodules, it is often indicative of bronchiolitis, where airway inflammation leads to secretions obstructing the distal airways. If associated with bronchiectasis, cystic fibrosis may be the underlying cause, as structural airway abnormalities predispose to recurrent infections. When accompanied by extensive consolidation, pneumonia is commonly suspected, with inflammatory exudation involving lung tissue.

2. Clinical Symptoms

When accompanied by cough, sputum production, and fever, infectious diseases such as bacterial pneumonia are more likely, as pathogens trigger an inflammatory response. Wheezing and chest tightness may suggest asthma complicated by bronchiolitis, with airway spasm superimposed on inflammation. Hemoptysis raises concern for pulmonary tuberculosis, where tuberculous lesions invade blood vessels causing bleeding.

3. Medical History

A long history of smoking may indicate chronic obstructive pulmonary disease (COPD) complicated by bronchiolitis, as harmful substances in tobacco damage the airways. A history of dust exposure is commonly associated with pneumoconiosis, where dust deposition causes chronic lung inflammation. A prior history of tuberculosis warrants vigilance for recurrence, as reactivation of old lesions can lead to the appearance of tree-in-bud signs.

4. Laboratory Tests

Elevated white blood cell count in complete blood count typically indicates bacterial infection, reflecting the body's immune response against pathogens. Identification of Mycobacterium tuberculosis in sputum culture confirms the diagnosis of pulmonary tuberculosis, providing direct microbiological evidence. Abnormal immune markers may suggest autoimmune diseases affecting the lungs, where immune dysregulation leads to pulmonary damage.

5. Response to Treatment

Improvement of symptoms and reduction of tree-in-bud signs after antibiotic use usually indicates bacterial infection, as antimicrobial agents suppress pathogen growth. Improvement following anti-tuberculosis therapy confirms active pulmonary tuberculosis, with targeted drugs controlling the infection. Symptom relief after administration of bronchodilators suggests an airway-spasm-related condition, as these medications alleviate airway obstruction.

In addition, diagnosing the underlying cause of tree-in-bud sign may also involve pulmonary function tests and bronchoscopy. If symptoms persist or worsen, timely and comprehensive evaluations should be performed to identify the exact etiology and prevent treatment delays.