Fig 5. CXR on follow-up showing re-expansion of the right lung
Pulmonary pseudocysts are often a sequela of blunt trauma to the chest wall, although cases following penetrating injuries to the chest have also been described. (1) Traumatic pulmonary pseudocysts often occur within 24 hours after the injury, may be single or multiple and are usually self-limiting with an excellent prognosis.(2) Multiple pseudocysts not related to trauma have been reported in neonates with hyaline membrane disease on mechanical ventilation. (3) Pseudocysts with predominant inflammatory processes are usually multiple, small and have been described in smokers, asthmatics and in cystic fibrosis patients.(4). Some authors have lumped pseudocysts with congenital cystic lung lesions under a broader group of cystic and pseudocystic pulmonary malformations. (CPPM) (5) Most CPPM lesions disappear in utero and are generally asymptomatic but may be responsible for fetal death, early life respiratory distress, recurrent pulmonary infections, or can transform to malignant lesions.(5) It is challenging to make a distinction between cystic and pseudocystic pulmonary lesions radiologically, on chest radiography or HRCT. Definitive diagnosis of a pseudocyst is only possible histopathologically, where the absence of epithelial cells or lung tissue is diagnostic of a pseudocyst. The management of congenital pulmonary airway malformation in asymptomatic children is controversial, some adopt a wait-and- see approach while others prefer a more aggressive approach of surgical excision to avert the risk for malignant transformation. In symptomatic patients, it is prudent to excise the cyst to achieve symptom relief.
  1. Gulbahar G. Diagnosing traumatic pulmonary pseudocyst. South Med J. 2009; 102(9):881. doi : 10.1097/SMJ.0b013e3181b187d3.
  2. Kanj A, Tabaja H, Soubani AO, Kanj N. Traumatic Pulmonary Pseudocyst Mimicking a Congenital Cystic Lung Disease. Case reports in pulmonology. 2018; 2018:7269694.doi : 10.1155/2018/7269694
  3. Harris H. Pulmonary pseudocysts in the newborn infant. Pediatrics. 1977; 59(2):199-204.  doi : 10.1136/adc.58.8.612.
  4. Tomashefski JF Jr, Bruce M, Stern RC, Dearborn DG, Dahms B. Pulmonary air cysts in cystic fibrosis: relation of pathologic features to radiologic findings and history of pneumothorax. Hum Pathol 1985; 16: 253-261.doi:  10.1016/s0046-8177(85)80011-3
  5. Rodríguez-Velasco A, López-Jara-Zárate EJ, Vargas MH, Ramírez-Figueroa JL, Furuya ME. Cystic and pseudocystic pulmonary malformations in children: Clinico-pathological correlation. Ann Diagn Pathol. 2019; 39:78-85. doi : 10.1016/j.anndiagpath.2019.02.005