The "Tree-in-Bud" Pattern

Appearance: Centrilobular branching linear structures with nodular tips (resembling a budding twig).

This pattern signifies the endobronchial spread of disease, typically reflecting bronchiolar impaction with mucus, pus, or fluid.

Key Differentials:

• Infection: Mycobacteria (TB, MAC), bacterial bronchopneumonia, viral, or fungal.

• Aspiration: Recurrent/chronic aspiration.

• Airway Disease: Cystic Fibrosis or allergic bronchopulmonary aspergillosis (ABPA).

Takeaway: It almost ALWAYS indicates an active inflammatory or infectious process, rarely malignancy.