A practical approach to cystic lung disease on HRCT

A lung cyst is defined as a round parenchymal lucency or area of low attenuation with a thin wall. They are not uncommon findings on high-resolution (HR) thoracic computed tomography (CT) and when identified, they require explanation. The differential diagnosis for diseases characterised by lung cysts is broad ranging from isolated chest disorders to rare multisystem diseases. This article provides a practical approach for evaluating lung cysts on HRCT, highlighting disorders in which the HRCT findings can be diagnostic as well as conditions where correlation with clinical history or biopsy is required.