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What are centrilobular nodules and tree in bud opacities?
- Centrilobular nodules are small (less than 1 cm) focal opacities located in the centers of secondary pulmonary lobules on CT, which spare pleural and fissural surfaces and are often ill-defined. These are due to pathologies that affect the bronchioles, pulmonary arterioles, and lymphatic vessels found in the central portions of secondary pulmonary lobules.
- Although seen in various disease conditions, their presence usually indicates infectious or inflammatory small airways disease such as by hypersensitivity pneumonitis, respiratory (smoking-related) bronchiolitis, and endobronchial spread of infection.
- Tree-in-bud opacities appear as tiny centrilobular branching structures on CT, most often in the lung periphery, which resemble budding trees.
- These are due to filling of the distal bronchioles and involvement of the adjacent alveoli, most often caused by infectious bronchiolitis, bronchitis, and aspiration.
- Most research has considered nodules, tree-in-bud, patchy shadow (consolidation, ground glass), cavities, bronchiectasis and fibrous stripes to be the major CT manifestations of NTM lung diseases, and indeed similar results were found in the present study. In research on the CT characteristics of Mycobacterium abscesses-LD carried out by Han et al. and Jeong et al. the main findings were that tree-in-bud, bronchiectasis, fibrous cavities and nodules, were present, mainly in the upper lung
Sources
- Chu H, Li B, Zhao L, Huang D, Xu J, Zhang J, Gui T, Xu L, Luo L, Zhang Z, Sun X. Tree-in-bud pattern of chest CT images for diagnosis of Mycobacterium abscesses. Int J Clin Exp Med. 2015 Oct 15;8(10):18705-12. PMID: 26770485; PMCID: PMC4694385.https://pmc.ncbi.nlm.nih.gov/articles/PMC4694385/
