A 46-year-old diabetic man has three weeks of productive cough with evening fever. HRCT chest shows clustered centrilobular nodules in the apicoposterior segment of the right upper lobe, each connected to a branching linear opacity, resembling a budding tree, with associated cavitation of an adjacent consolidation. This 'tree-in-bud' pattern most specifically indicates:
- A Endobronchial spread of active infection ✓
- B Haematogenous miliary dissemination
- C Lymphangitic carcinomatosis
- D Cryptogenic organising pneumonia
Correct answer: A. Endobronchial spread of active infection
Explanation
Tree-in-bud represents impacted, dilated bronchioles filled with pus, mucus or caseous material, with their feeding bronchioles forming the branches. Centrilobular location with cavitation and upper lobe predominance points to endobronchial spread of post-primary tuberculosis. Miliary nodules are diffuse, random and discrete without branching connections, and lymphangitic carcinomatosis follows septal lines rather than bronchiolar impaction, killing both tempting distractors.
Reference: Grainger and Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.