CT Characteristics and Pathologic Basis of Solitary Cystic Lung Cancer

HomeRadiologyVol. 291, No. 2 PreviousNext Reviews and CommentaryFree AccessEditorialCT Characteristics and Pathologic Basis of Solitary Cystic Lung CancerPatricia J. Mergo , Carlos A. RojasPatricia J. Mergo , Carlos A. RojasAuthor AffiliationsFrom the Department of Radiology, Mayo Clinic, 4500 San Pablo Rd, Jacksonville, FL 32224.Address correspondence to P.J.M. (e-mail: [email protected]).Patricia J. Mergo Carlos A. RojasPublished Online:Mar 12 2019https://doi.org/10.1148/radiol.2019190329MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In See also the article by Tan and Gao et al in this issue.IntroductionLung cancer associated with cystic airspaces has been reported by many groups and accounts for approximately 1%–3.7% of cases of non–small cell lung cancer (1–3). Scholten and colleagues (4) showed that 22% of the missed lung cancers in a lung cancer screening program (Dutch-Belgium lung cancer screening trial) had the appearance of “bulla with wall thickening.”In this issue of Radiology, Tan and colleagues (5) publish findings in the largest cohort of patients with pathologically proven lung cancer associated with cystic airspaces. The article highlights the CT features of lung cancer associated with cystic spaces and their correlates at histopathologic examination. Furthermore, it sheds some light on the pathophysiology of cystic airspace formation in these lesions. Similarly to previously published studies, this study corroborates that adenocarcinoma is the main histopathologic diagnosis in these lesions, followed by squamous cell carcinoma. Interestingly, only 46% of the patients in this study had a history of smoking, less than the reported percentage in a prior similar study (1). No lobar predilection was found; however, a peripheral location was most commonly seen.A pulmonary cyst is defined as “a round parenchymal lucency or low-attenuating area with a well-defined interface with normal lung on chest CT” in the Fleischner Society glossary of terms (6). Pulmonary cysts are common imaging findings, reported to be present in up to 8% of patients older than 40 years of age, and their prevalence increases with age (7). Multiple pulmonary cysts can be seen in diseases such as lymphangioleiomyomatosis, Langerhans cell histiocytosis, and lymphoid interstitial pneumonia, among others. Cysts in these conditions do not pose a known risk for developing bronchogenic cancer within the cysts (3). The term “cystic airspace” attempts to unify multiple lesions with similar imaging characteristics at CT, such as cysts, bullae, blebs, cavities, and pneumatoceles.Tan and colleagues define solitary cystic lung cancer as “a special type of lung cancer that manifests as a thin-walled cystic airspace where the cyst walls are 4 mm or thinner at initial CT imaging.” They discuss the pathophysiology behind the cystic changes that can be seen in non–small cell lung cancers as the result of bronchiolar obstruction by fibrous tissue or tumor cells with a “check-valve” mechanism. As the tumor grows, it can be seen at CT as a nodule along the inner or outer wall of the cystic space or as surrounding ground-glass opacities. The fibrous tissue deposition by the tumor cells can result in local architectural distortion and irregularity of the cyst walls. With continued enlargement, the tumor can fill and replace the cystic airspaces with a solid component. With this pathophysiologic description, it is conceivable that an early non–small cell lung cancer could manifest as cyst formation because of obstruction of the small airway without a detectable solid component.It is important for the radiologist to become familiar with the imaging features that are concerning for underlying malignancy when evaluating a cystic lesion in the lung. These include nonuniform cystic walls, septations within the cyst, wall nodule, ground-glass opacities around the cyst, and irregular margin. The most common imaging feature encountered in non–small cell lung cancer with cystic spaces is nonuniform cyst walls, followed by septation of the cyst and wall nodules. The presence of these imaging findings should raise suspicion about the underlying malignancy and prompt short-term follow-up examination or tissue diagnosis on a case-by-case basis. For lesions with solid nodules larger than 8 mm, PET imaging can help in the work-up of these patients, demonstrating increased metabolic activity (1).Currently, there are no specific recommendations on how to measure or follow up cystic lesions in the lungs according to the Fleischner society guidelines (8) or Lung-RADS (9). Fintelmann and colleagues (1) evaluated the natural course of non–small cell lung cancer with cystic airspaces in 30 patients. They reported a median of 35 months for the development of wall thickening or mural nodule in a preexistent cystic air space. The calculated median doubling time of the cyst diameter was 454 days, greater than that of malignant solid nodules (10). Furthermore, the cyst diameter decreased in 23% of the lesions in association with an increase in wall thickness, suggesting that an overall increase in the lesion diameter is not a reliable method of evaluating for progression of disease in these lesions, in contrast to solid nodules.In conclusion, lung cancer with cystic airspaces is an uncommon morphologic feature of non–small cell lung cancer, likely to be seen in busy lung cancer screening programs. It is important to recognize these lesions and to identify the concerning imaging features that suggest malignancy. Future directions should include continued understanding of the behavior of these lesions through observational studies and learning how to best measure these lesions and how to evaluate for progression on longitudinal examinations. Furthermore, follow-up recommendations are needed to guide management when a lesion with cystic airspaces is encountered incidentally at chest CT or in a lung cancer screening examination.Disclosures of Conflicts of Interest: P.J.M. disclosed no relevant relationships. C.A.R. disclosed no relevant relationships.References1. Fintelmann FJ, Brinkmann JK, Jeck WR, et al. Lung cancers associated with cystic airspaces: natural history, pathologic correlation, and mutational analysis. J Thorac Imaging 2017;32(3):176–188 . Crossref, Medline, Google Scholar2. Mascalchi M, Attinà D, Bertelli E, et al. Lung cancer associated with cystic airspaces. J Comput Assist Tomogr 2015;39(1):102–108 . Crossref, Medline, Google Scholar3. Farooqi AO, Cham M, Zhang L, et al. Lung cancer associated with cystic airspaces. AJR Am J Roentgenol 2012;199(4):781–786 . Crossref, Medline, Google Scholar4. Scholten ET, Horeweg N, de Koning HJ, et al. Computed tomographic characteristics of interval and post screen carcinomas in lung cancer screening. Eur Radiol 2015;25(1):81–88 . Crossref, Medline, Google Scholar5. Tan Y, Gao J, Wu C, et al. CT characteristics and pathologic basis of solitary cystic lung cancer. Radiology 2019;291:495–501. Link, Google Scholar6. Hansell DM, Bankier AA, MacMahon H, McLoud TC, Müller NL, Remy J. Fleischner Society: glossary of terms for thoracic imaging. Radiology 2008;246(3):697–722 . Link, Google Scholar7. Araki T, Nishino M, Gao W, et al. Pulmonary cysts identified on chest CT: are they part of aging change or of clinical significance? Thorax 2015;70(12):1156–1162 . Crossref, Medline, Google Scholar8. MacMahon H, Naidich DP, Goo JM, et al. Guidelines for management of incidental pulmonary nodules detected on CT images: from the Fleischner Society 2017. Radiology 2017;284(1):228–243 . Link, Google Scholar9. American College of Radiology. Lung imaging reporting and data system (Lung-RADS) version 1.0. http://www.acr.org/Quality-Safety/Resources/LungRADS. Published 2014. Accessed January 22, 2019. Google Scholar10. Detterbeck FC, Gibson CJ. Turning gray: the natural history of lung cancer over time. J Thorac Oncol 2008;3(7):781–792 . Crossref, Medline, Google ScholarArticle HistoryReceived: Feb 12 2019Revision requested: Feb 18 2019Revision received: Feb 20 2019Accepted: Feb 21 2019Published online: Mar 12 2019Published in print: May 2019 FiguresReferencesRelatedDetailsCited ByThe Multi-slice Spiral Computed Tomography (MSCT) Features of Thin-Walled Cystic Lung Cancer with Ground Glass OpacityYejunYu2021 | Iranian Journal of Radiology, Vol. 18, No. 2Accompanying This ArticleCT Characteristics and Pathologic Basis of Solitary Cystic Lung CancerMar 12 2019RadiologyRecommended Articles CT Characteristics and Pathologic Basis of Solitary Cystic Lung CancerRadiology2019Volume: 291Issue: 2pp. 495-501Lung Cancers Associated with Cystic Airspaces: Underrecognized Features of Early DiseaseRadioGraphics2018Volume: 38Issue: 3pp. 704-717Invited Commentary: Early Lung Cancer and Cystic AirspacesRadioGraphics2018Volume: 38Issue: 3pp. 717-718Updated Fleischner Society Guidelines for Managing Incidental Pulmonary Nodules: Common Questions and Challenging ScenariosRadioGraphics2018Volume: 38Issue: 5pp. 1337-1350Practical Imaging Interpretation in Patients Suspected of Having Idiopathic Pulmonary Fibrosis: Official Recommendations from the Radiology Working Group of the Pulmonary Fibrosis FoundationRadiology: Cardiothoracic Imaging2021Volume: 3Issue: 1See More RSNA Education Exhibits Basics of Lung Cancer Related to Cysts and Enlarged Cystic Air-spaces: Survival Guide for General RadiologistDigital Posters2022Radiologic-Pathologic Correlation of Cystic Lung DiseasesDigital Posters2020Management of Solitary Pulmonary Nodules: Pushing the Limits Beyond the GuidelinesDigital Posters2019 RSNA Case Collection LymphangioleiomyomatosisRSNA Case Collection2021Granulomatous lymphocytic interstitial lung disease RSNA Case Collection2021Bleomycin induced lung toxicityRSNA Case Collection2021 Vol. 291, No. 2 Metrics Altmetric Score PDF download