Centrilobular lung nodules refer to a HRCT chest imaging descriptor for small 5-10 mm lung nodules which are anatomically located centrally within secondary pulmonary lobules. The term is applied on the basis of location of the nodule and not its morphology, that is they may be well-defined or poorly-defined ground glass in appearance. If extremely small they are termed centrilobular micronodules.
Centrilobular nodules can be observed in a wide variety of lung pathology. In particular, pathologies that involve the bronchioles and the arterioles (i.e., bronchiolitis and vasculitis) as both are located centrally in the secondary pulmonary lobule. Specific conditions include:
When centrilobular nodules are interspersed with linear and branching densities, it is then termed a tree-in-bud pattern.
Radiographic features
CT
HRCT chest
On HRCT chest, centrilobular nodules are typically found around the small airways and spare the subpleural surfaces. They are typically at least 5-10 mm away from the pleural surfaces ref.
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