Tree-in-Bud Pattern of Pulmonary Tuberculosis on Thin-Section CT: Pathological Implications

Area of Science:

• Pulmonary Medicine
• Radiology
• Pathology

Background:

• The "tree-in-bud pattern" on thin-section lung CT scans is characterized by centrilobular branching structures resembling a budding tree.
• Understanding the pathological basis of this imaging finding is crucial for accurate diagnosis.

Purpose of the Study:

• To investigate the pathological basis of the tree-in-bud lesion observed in lung imaging.
• To correlate radiological findings with pathological specimens in cases of pulmonary tuberculosis.

Main Methods:

• Review of pathological specimens from bronchograms of normal lungs.
• Examination of contract radiographs of post-mortem lungs with active pulmonary tuberculosis.
• Radiological and pathological correlation to define the components of the tree-in-bud pattern.

Main Results:

• The "tree" component corresponds to the intralobular inflammatory bronchiole.
• The "bud" component represents inflammatory material filling alveolar ducts, which are larger than the bronchioles.
• Clusters of micronodules observed in tuberculosis radiographs were identified as clusters of tree-in-bud lesions within secondary pulmonary lobules.
• No evidence of lung parenchymal lymphatic involvement was found in the studied specimens.

Conclusions:

• The tree-in-bud pattern is pathologically defined by inflammation of bronchioles and alveolar ducts.
• This pattern is a key radiological manifestation in pulmonary tuberculosis.
• The study clarifies the anatomical structures corresponding to the tree-in-bud imaging finding.