000 Cysts in the Lung

    • TCV Definition: Lung Cyst

      • Etymology
        Derived from the Greek word “kystis,” meaning bladder or sac.
      • AKA
        Pulmonary cyst
      • Definition
        • What is it?
          A lung cyst is a gas-filled space within the lung parenchyma, characterized by a thin, perceptible wall typically less than 2-4 mm in thickness. These cysts can vary in size and distribution and are associated with a wide range of underlying conditions.
        • Caused by
          • Most common causes
            • Smoking-related diseases
              • Pulmonary Langerhans cell histiocytosis (PLCH): A frequent cause in smokers, typically with upper lobe predominance and cysts of varying wall thickness.
              • Emphysema-related bullae: Large, thin-walled air-filled spaces caused by parenchymal destruction in smokers.
            • Congenital disorders
              • Congenital pulmonary airway malformation (CPAM): Seen in pediatric populations but may persist into adulthood.
              • Bronchogenic cysts: Often incidental findings with well-defined, thin-walled cysts.
            • Cystic lung diseases
              • Lymphangioleiomyomatosis (LAM): Primarily affects women of childbearing age, characterized by diffuse cystic changes.
              • Birt-Hogg-Dubé syndrome: Associated with basal-predominant cysts and genetic mutations in the folliculin gene.
          • Other causes include
            • Infectious causes
              • Pneumocystis jirovecii pneumonia (PJP): Common in immunocompromised patients, producing thin-walled cysts.
              • Tuberculosis: Can produce thin-walled cavities resembling cysts.
              • Post-viral pneumonias: Rarely associated with cyst formation.
            • Inflammatory causes
              • Pulmonary Langerhans cell histiocytosis (PLCH): Smoking-related, with irregular, thick- and thin-walled cysts predominantly in the upper lobes.
              • Lymphoid interstitial pneumonia (LIP): Associated with lower lobe predominance and bronchovascular bundles.
              • Sarcoidosis: Late-stage disease may cause cyst formation.
            • Neoplastic causes
              • Cystic adenocarcinoma of the lung: Malignant transformation presenting with cystic components.
              • Metastatic disease: Rarely associated with thin-walled cystic changes.
            • Other causes
              • Trauma: Pneumatoceles following blunt trauma or infection.
              • Drug-induced lung injury: Medications like methotrexate or amiodarone.
        • Resulting in
          • Single cyst: Typically focal pathology such as neoplasm, trauma, or localized infection.
          • Multiple cysts: Indicative of diffuse lung disease (e.g., LAM, PLCH) or systemic involvement.
          • Potential complications: Include pneumothorax, secondary infection, and, rarely, malignant transformation.

      Lymphangioleiomyomatosis (LAM),

      • LAM 
        Ashley Davidoff MD TheCommonvein.net
    • Langerhans cell histiocytosis (PLCH),
    • Pulmonary Langerhans Cell Histiocytosis
      Thiin Walled Bizarre Shaped Upper Lobe Cysts
      Ashley Davidoff MD TheCommonVein.net
      • Langerhans Cell HistiocytosisCT scan shows multiple small cysts sometimes irregular in shape predominantly in the upper lobes. The cysts are round and air filled large and are between 5mm-8mm
    • Birt-Hogg-Dubé syndrome (BHD), and
    • Lymphoid interstitial pneumonia (LIP), although the differential diagnosis can at times expand to encompass other extremely rare etiologies
    • Amyloidosis
    • Light Chain Deposition Disease
    • Neurofibromatosis
  • Less Common
    •  Sjögren syndrome
    •  light chain deposition disease
    •  Ehlers Danlos syndrome type IV
    •  fire-eater’s lung (pneumatoceles)
    •  lymphomatoid granulomatosis
    • neurofibromatosis
    • congenital pulmonary airway (cystic adenomatoid) malformation,
    • smoking related small airways injury [
    • Proteus syndrom
      • Look Alikes
        • Emphysema
          • No wall
          • Central soft tissue elements
        • Blebs
        • Bullae
          •  >1 cm in diameter, bounded by a
          • thin wall (<1 mm)
          • background emphysema
        • Bronchiectasis
          • continuity with airways
        • Honeycombing
          • enlarged airspaces
            • .3 -1.0cms (up to 2.5cms)
          • thick fibrous walls
          • End stage fibrotic disease
          • subpleural
          • stacked
        • Pneumatoceles
          • thin-walled parenchymal cyst
          • Infection
            • bacterial pneumonia eg children
            • PCP  Pneumocystis jirovecii,
            • coccidioidomycosis,
            • hyperimmunoglobulinemia E syndrome,
            • staphylococcal pneumonia
          • Chest Trauma
  • LAM

    • LAM and LYMPHANGIOLEIOMYOMAS in the ABDOMEN
      38-year-old patient with progressive dyspnea and cough
      CXR (scout for CT) shows hyperinflated lungs with increased lung volumes with bilateral and extensive thin-walled cysts surrounded by very little normal lung parenchyma. The cysts are round and thin-walled except for air filled large irregular pocket in the right apex (image 27628/29) . Some of the cysts do not have walls at all and others have an irregular configuration.
      In the abdomen multiple low density lymphangioleiomyomas are present that are due to lymphatic obstruction.
      Ashley Davidoff MD TheCommonVein.net

Upper

The presence of micronodules or cysts excludes a confident diagnosis of UIP.45 On HRCT, micronodules are discrete, round, soft-tissue densities of <3 mm.7 Cysts are low attenuation areas that tend to be round and thin-walled (<2 mm). Cysts in the lung often contain air but may also contain fluid or solid material.7

 

  1.  A Stepwise Diagnostic Approach to Cystic Lung Diseases for Radiologists.

    Lee KC, Kang EY, Yong HS, et al. Korean Journal of Radiology. 2019;20(9):1368-1380. doi:10.3348/kjr.2019.0057.

  2. Cystic and Cavitary Lung Diseases: Focal and Diffuse.

    Ryu JH, Swensen SJ. Mayo Clinic Proceedings. 2003;78(6):744-52.

  3. Cystic Lung Diseases: Algorithmic Approach.

    Raoof S, Bondalapati P, Vydyula R, et al. Chest. 2016;150(4):945-965. doi:10.1016/j.chest.2016.04.026.

  4. Isolated Cystic Lung Disease: An Algorithmic Approach to Distinguishing Birt-Hogg-Dubé Syndrome, Lymphangioleiomyomatosis, and Lymphocytic Interstitial Pneumonia.  Escalon JG, Richards JC, Koelsch T, Downey GP, Lynch DA.  AJR. American Journal of Roentgenology. 2019;212(6):1260-1264.

  5. CT Findings of Pulmonary Cysts.

    Arango-Díaz A, Martínez-de-Alegría-Alonso A, Baleato-González S, et al.  Clinical Radiology. 2021;76(7):548.e1-548.e12.

  6. Cystic Lung Diseases: Radiological Aspects.

    Valente T, Guarino S, Lassandro G, et al.  Clinical Radiology. 2022;77(5):e337-e345.

  7.   Differentiation Between Lymphangioleiomyomatosis and Birt-Hogg-Dubé Syndrome: Analysis of Pulmonary Cysts on CT Images.

    Park HJ, Chae EJ, Do KH, Lee SM, Song JW.

    AJR. American Journal of Roentgenology. 2019;212(4):766-772.

  8. Multiple Cystic Lung Disease.

    Ferreira Francisco FA, Soares Souza A, Zanetti G, Marchiori E. European Respiratory Review : An Official Journal of the European Respiratory Society. 2015;24(138):552-64.

  9. Diagnosis of Cystic Lung Diseases: A Position Statement From the UK Cystic Lung Disease Rare Disease Collaborative Network.

    Johnson SR, Shaw DE, Avoseh M, et al.  Thorax. 2024;79(4):366-377. doi:10.1136/thorax-2022-219738.

  10. High-Resolution Computed Tomography of Cystic Lung Disease.

    Kusmirek JE, Meyer CA.

    Seminars in Respiratory and Critical Care Medicine. 2022;43(6):792-808. .

  11. Lymphangioleiomyomatosis and Other Cystic Lung Diseases.

    Koslow M, Lynch DA, Cool CD, Groshong SD, Downey GP.  Immunology and Allergy Clinics of North America. 2023;43(2):359-377.

  12. Ultra-Rare Cystic Disease.

    Elia D, Torre O, Cassandro R, Caminati A, Harari S.  European Respiratory Review : An Official Journal of the European Respiratory Society. 2020;29(157):190163.