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Atypical pulmonary cysts: Why to care
THORACIC ONCOLOGY AND CHEST PROCEDURES NETWORK
Lung Cancer Section
Since the American College of Radiology (ACR) updated its Lung CT Screening Reporting & Data System (Lung-RADS) to include atypical pulmonary cysts in 2022, there has been little discussion among chest physicians regarding the significance of pulmonary cysts and why these changes were made.
Lung-RADS 2022 defined atypical pulmonary cysts as single, unilocular cysts with a wall thickness greater than 2 mm or any multilocular cysts. These can be uniform, asymmetric, or have a focal nodularity. This change was prompted by data derived from multiple studies. First, a finding that 3.6% of lung cancers were associated with cysts at baseline.1 This was followed by a reanalysis of the NELSON trial’s missed cancers showing 22% of those overlooked during initial screening had findings of cystic disease, reaffirming the significance of atypical pulmonary cysts.2 Though the number is low, we now know 1.1% of all cancers present as an atypical cyst, with 4.7% of them being malignant.3
Based on these studies, cysts are a baseline Lung-RADS 4A—a finding that correlates to a higher risk and needs to be followed with a short-term CT scan in 3 months vs a PET. ACR does recommend reserving PET scans for wall thickness > 8 mm. If the repeat CT scan is stable, then the Lung-RADS designation is dropped to a 3 for follow-up.
References
1. Farooqi AO, Cham M, Zhang L, et al. Lung cancer associated with cystic airspaces. AJR Am J Roentgenol. 2012;199(4):781-786.
2. Scholten ET, Horeweg N, Koning HJ, et al. Computed tomographic characteristics of interval and post screen carcinomas in lung cancer screening. Eur Radiol. 2015;25(1):81-88.
3. Mascalchi M, Attinà D, Bertelli E, et al. Lung cancer associated with cystic airspaces. J Comput Assist Tomogr. 2015;39(1):102-108.
THORACIC ONCOLOGY AND CHEST PROCEDURES NETWORK
Lung Cancer Section
Since the American College of Radiology (ACR) updated its Lung CT Screening Reporting & Data System (Lung-RADS) to include atypical pulmonary cysts in 2022, there has been little discussion among chest physicians regarding the significance of pulmonary cysts and why these changes were made.
Lung-RADS 2022 defined atypical pulmonary cysts as single, unilocular cysts with a wall thickness greater than 2 mm or any multilocular cysts. These can be uniform, asymmetric, or have a focal nodularity. This change was prompted by data derived from multiple studies. First, a finding that 3.6% of lung cancers were associated with cysts at baseline.1 This was followed by a reanalysis of the NELSON trial’s missed cancers showing 22% of those overlooked during initial screening had findings of cystic disease, reaffirming the significance of atypical pulmonary cysts.2 Though the number is low, we now know 1.1% of all cancers present as an atypical cyst, with 4.7% of them being malignant.3
Based on these studies, cysts are a baseline Lung-RADS 4A—a finding that correlates to a higher risk and needs to be followed with a short-term CT scan in 3 months vs a PET. ACR does recommend reserving PET scans for wall thickness > 8 mm. If the repeat CT scan is stable, then the Lung-RADS designation is dropped to a 3 for follow-up.
References
1. Farooqi AO, Cham M, Zhang L, et al. Lung cancer associated with cystic airspaces. AJR Am J Roentgenol. 2012;199(4):781-786.
2. Scholten ET, Horeweg N, Koning HJ, et al. Computed tomographic characteristics of interval and post screen carcinomas in lung cancer screening. Eur Radiol. 2015;25(1):81-88.
3. Mascalchi M, Attinà D, Bertelli E, et al. Lung cancer associated with cystic airspaces. J Comput Assist Tomogr. 2015;39(1):102-108.
THORACIC ONCOLOGY AND CHEST PROCEDURES NETWORK
Lung Cancer Section
Since the American College of Radiology (ACR) updated its Lung CT Screening Reporting & Data System (Lung-RADS) to include atypical pulmonary cysts in 2022, there has been little discussion among chest physicians regarding the significance of pulmonary cysts and why these changes were made.
Lung-RADS 2022 defined atypical pulmonary cysts as single, unilocular cysts with a wall thickness greater than 2 mm or any multilocular cysts. These can be uniform, asymmetric, or have a focal nodularity. This change was prompted by data derived from multiple studies. First, a finding that 3.6% of lung cancers were associated with cysts at baseline.1 This was followed by a reanalysis of the NELSON trial’s missed cancers showing 22% of those overlooked during initial screening had findings of cystic disease, reaffirming the significance of atypical pulmonary cysts.2 Though the number is low, we now know 1.1% of all cancers present as an atypical cyst, with 4.7% of them being malignant.3
Based on these studies, cysts are a baseline Lung-RADS 4A—a finding that correlates to a higher risk and needs to be followed with a short-term CT scan in 3 months vs a PET. ACR does recommend reserving PET scans for wall thickness > 8 mm. If the repeat CT scan is stable, then the Lung-RADS designation is dropped to a 3 for follow-up.
References
1. Farooqi AO, Cham M, Zhang L, et al. Lung cancer associated with cystic airspaces. AJR Am J Roentgenol. 2012;199(4):781-786.
2. Scholten ET, Horeweg N, Koning HJ, et al. Computed tomographic characteristics of interval and post screen carcinomas in lung cancer screening. Eur Radiol. 2015;25(1):81-88.
3. Mascalchi M, Attinà D, Bertelli E, et al. Lung cancer associated with cystic airspaces. J Comput Assist Tomogr. 2015;39(1):102-108.