Pulmonary cysts are round, thin-walled, low attenuation spaces/lucencies in the lung. Lung cysts usually contain air but occasionally also contain fluid or solid material 5.
In contradistinction to all other organs, the term cyst as used in the lung is a misnomer, as it usually refers to a contained focus of gas, not fluid.
Pulmonary cysts can be congenital or acquired. Multiple lung cysts in a child may be associated with an underlying process although this is rare, e.g. pleuropulmonary blastomas 1.
There are several specific types of thin-walled cystic spaces in the lungs 6,7:
- bleb: pleural/subpleural, ≤1-2 cm diameter
- bulla: pleural/subpleural, ≥1-2 cm diameter
- honeycombing: subpleural stacks of cysts, typically 3-10 mm diameter with walls 1-3 mm in thickness
- pneumatocele: usually transient cystic airspace within the lung, usually due to pneumonia or trauma
There are several mimics of pulmonary cysts:
- pulmonary cavity: surrounded by mass, nodule, or consolidation, creating wall thickness >2-4 mm 4-6
- emphysema: lucencies without wall and with central vessel
- cystic bronchiectasis: contiguous with other airways
- 1. Priest JR, Williams GM, Hill DA et-al. Pulmonary cysts in early childhood and the risk of malignancy. Pediatr. Pulmonol. 2009;44 (1): 14-30. doi:10.1002/ppul.20917 - Pubmed citation
- 2. Dähnert W. Radiology Review Manual. Lippincott Williams & Wilkins. (2011) ISBN:1609139437. Read it at Google Books - Find it at Amazon
- 3. Webb WR, Higgins CB. Thoracic Imaging, Pulmonary and Cardiovascular Radiology. Lippincott Williams & Wilkins. (2010) ISBN:1605479764. Read it at Google Books - Find it at Amazon
- 4. Gadkowski LB, Stout JE. Cavitary pulmonary disease. Clin. Microbiol. Rev. 2008;21 (2): 305-33, table of contents. doi:10.1128/CMR.00060-07 - Free text at pubmed - Pubmed citation
- 5. Cantin L, Bankier AA, Eisenberg RL. Multiple cystlike lung lesions in the adult. AJR Am J Roentgenol. 2010;194 (1): W1-W11. doi:10.2214/AJR.09.3540 - Pubmed citation
- 6. Hansell DM, Bankier AA, MacMahon H, McLoud TC, Müller NL, Remy J. Fleischner Society: glossary of terms for thoracic imaging. (2008) Radiology. 246 (3): 697-722. doi:10.1148/radiol.2462070712 - Pubmed
- 7. Ryu JH, Swensen SJ. Cystic and cavitary lung diseases: focal and diffuse. (2003) Mayo Clinic proceedings. 78 (6): 744-52. doi:10.4065/78.6.744 - Pubmed