Fig 5. CXR on follow-up showing re-expansion of the right lung
Discussion
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) Blunt chest trauma often results in lung contusions and lacerations, but rarely cystic lesions.(2) 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. (3)Multiple pseudocysts have also been reported in neonates with hyaline membrane disease on continuous distending pressures from mechanical ventilation. (4) A previous case reported a 7-year-old who had multiple cysts that complicated with a pneumothorax. Histology revealed inflammatory cell infiltrate in the interstitium, alveolar haemorrhage and cysts that lacked an epithelial lining.(5) Pseudocysts with predominant inflammatory processes have also been seen in smokers, asthmatics and in cystic fibrosis patients. (6). (7) In our case, previous inflammation could not be excluded, even though no inflammatory cells were observed. Moreover, post inflammatory cysts are usually multiple and small, (7) but our case had a giant single cystic lesion. Some authors have lumped pseudocysts with congenital cystic lung lesions under a broader group of cystic and pseudocystic pulmonary malformations. (CPPM) (8) 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.(8) 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. In our case, the pseudocyst was excised to relieve the compressive effects on adjacent lung tissue.
Conclusion
This case describes a rare case of a spontaneous pulmonary pseudocyst in a 2-year-old child. To the best of our knowledge, this is the first such case to be reported in literature.
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