Cystic Lung Lesions, a pediatric clinical case review and discussion

Patient Presentation
In clinic the residents were discussing a a 4-year-old female who had recurrent pneumonia. “They figured out that it wasn’t straightforward pneumonia but was a pulmonary sequestration. Surgery removed it and now she is back on the floor after a short PICU stay and is doing well. I have to say that I had to read up again about these. I always get confused with all these lung lesions because the names seem to be so similar. The diagnosis was an extralobar pulmonary sequestration. The one that sort of acts like its own little lobe of the lung with its own pleura and blood supply,” one resident remarked. “I know that this was part of embryology that was harder for me. I have to look these up too. If I remember right she shouldn’t have any long term problems right? If everything goes well with the surgery and her recovery, right?” a second resident said. “Yeah, she should be fine and hopefully this will stop the pneumonias and her being in the hospital,” commented the first resident.

Case Image

Figure 147 – CXR PA and lateral (above) shows a large round opacity in the left lower lobe posteriorly that abuts the diaphragm. Coronal T1 MRI with contrast of the chest (below) shows a uniformly enhancing mediastinal mass that extends into the retrocrural regions of the chest bilaterally and that has a feeding vessel arising from the aorta.

Discussion
Cystic lung lesions can be confusing because of terminology and overlapping presentations and radiological appearances. Cystic lung lesions in children are usually congenital and benign especially in young children. In older children oncological and genetic causes also should be considered especially if there are multifocal lesions.

Learning Point

Cysts, Emphysema and Pneumatocoeles
- Cysts are a gas-filled round parenchymal lesions with thin wall that is < 2 mm in size. Lung cysts are associated with aging especially after age 40.
- Emphysema is a “permanent enlargement of alveolar spaces with disruption of septa, and compression of surrounding parenchyma.” It is distal to the bronchiole and does not have a wall.
- Pneumatocoeles are lung spaces that occur after trauma or infection and filled with gas.
- Congenital Cystic Lung Malformations
  - While many of these lesions are found on prenatal ultrasound, they may present only years later with recurrent pneumonia or due to compression of adjacent structures. They have a rare risk of malignant transformation.
  - Incidence is about 2500-8000 live births
  - Treatment depends on presentation and patient age with monitoring, prenatal and post-natal surgical interventions. Asymptomatic lesions may be monitored and possibly surgically treated depending on the lesion type
    - Foregut Duplications and Bronchogenic Cysts
      - Pathology: Occur because of “…anomalous budding of the foregut endoderm from which the respiratory tract and upper gastrointestinal tract develop, as well as other organ systems.”
      - Location: Bronchogenic cysts are most common in the mediastinum around the tracheal bifurcation. Also seen in supra- and sub-diaphragmatic and intraparenchmal locations
      - Appearance: Unilocular without septations
      - Fluid: Mucinous but can be purulent or bloody if there is infection or hemorrhage
      - DDX: Abscess, large cyst congenital pulmonary airway malformation but both of these are multiseptated
      - Presentation: Incidental finding, superimposed infection, compression of adjacent structures causing symptoms
    - Congenital Pulmonary Airway Malformations (CPAMs)
      - Most common lower respiratory tract malformation. Size, histological appearance and blood supply have been used for classification.
      - Occur because of airway obstruction during development.
        
        Large Cyst CPAM
        
        Appearance: > 2 cm in size, may be multiloculated, usually without a systemic blood supply
        
        Fluid: Mucinous and looks like bronchioles without cartilage or glands
        
        DDX: Bronchogenic cyst, pulmonary interstitial emphysema, pneumatocoele and pleuropulmonary blastoma (cystic type)
        
        Presentation: Prenatal ultrasound finding, hydrops fetalis, compression of adjacent structures, infection
        
        Small Cyst CPAM
        
        Appearance: < 2 cm in size, usually multiple, uniform cysts, may have blood supply
        
        Fluid: Mucoid, dilated bronchiole-like structure
        
        DDX: Intralobar sequestration (ILS) and hybrid lesions
        
        Presentation: Prenatal ultrasound, neonatal respiratory distress
    - Bronchopulmonary Sequestration
      - Pathology: No connection to tracheobronchial tree and have systemic arterial supply usually from the thoracic or abdominal aorta and venous drainage is through thoracic or systemic veins.
      - Extralobar sequestrations (ELS) have their own pleural lining and lung tissue similar to an accessory lobe. Intralobar sequestrations (ILS) are “non-functioning lung segments embedded within the pleura of the lung lobe in which they arise.””
      - Location: ELS thoracic cavity or infradiaphragmatic often in the left lower thoracic area, ILS are located within the lung.
      - Appearance: ELS looks like bronchi and alveoli with large vessels. ILS looks similar to small cyst CPAM
      - Fluid: Mucoid
      - DDX: Small cyst CPAM, chronic pneumonia
      - Presentation: ELS often has other congenital anomalies, ILS is intraparenchymal lesion, compression of adjacent structures
    - Pulmonary Hyperplasia (PH) and Congenital Lobar Overinflation (CLO)
      - Pathology: PH is caused by overgrowth of pulmonary parenchymal tissue causing airway obstruction in fetal life. CLO is caused by air trapping in the pulmonary lobe
      - Appearance: PH has increased alveolar counts. CLO has alveolar distension and is often in the upper lobe
      - DDX: Small cyst CPAM, true emphysema
      - Presentation: PH prenatal diagnosis with associated fetal hydrops or polyhydramnios . Both PH and CLO can present with compression of adjacent structures causing symptoms
  - Neoplasms
    - Pleuropulmonary Blastoma (PPB)
      - Pathology: most common primary parenchymal lung tumor. Presentation age depends on type with older ages having worse prognosis. Associated with DICER1 gene.
      - Location: peripheral multiloculated cysts that may have hemorrhage in them
      - Appearance: 3 types based on cystic and solid components
      - DDX: CPAMs
      - Presentation: Prenatal diagnosis, respiratory distress, pneumothorax, abdominal mass with some types, systemic symptoms such as fever, malaise
  - Other lesions
    - Birt-Hogg-Dube syndrome
    - Ehler-Danlos syndrome
    - Langerhan cell histiocytosis
    - Lymphangioleiomyomatosis
    - Marfan syndrome
  Questions for Further Discussion
  1. What are indications for more evaluation of recurrent pneumonia?
  2. What evaluation for recurrent pneumonia would you do?
  3. What are causes of respiratory distress? A review can be found here
  
  Related Cases
  To Learn More
  To view pediatric review articles on this topic from the past year check PubMed.
  
  Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.
  
  Information prescriptions for patients can be found at MedlinePlus for these topics: Birth Defects and Respiratory Diseases.
  
  To view current news articles on this topic check Google News.
  
  To view images related to this topic check Google Images.
  
  To view videos related to this topic check YouTube Videos.
  
  Cortes-Santiago N, Deutsch GH. Pediatric Cystic Lung Lesions. Surgical Pathology Clinics. 2020;13(4):643-655. doi:10.1016/j.path.2020.07.002
  
  Hegde BN, Tsao K, Hirose S. Management of Congenital Lung Malformations. Clinics in Perinatology. 2022;49(4):907-926. doi:10.1016/j.clp.2022.08.003
  
  Valente T, Guarino S, Lassandro G, et al. Cystic lung diseases: radiological aspects. Clin Radiol. 2022;77(5):e337-e345. doi:10.1016/j.crad.2022.01.044
  
  Author
  Donna M. D’Alessandro, MD
  Professor of Pediatrics, University of Iowa
Related

Related

Discover more from Pediatric Education