Malformations and anomalies

When the lung bud fails to separate normally from the oesophagus through the tracheo-oesophageal septum, it results in an oesophageal atresia that can take different forms. This atresia can be combined with a tracheo-oesophageal fistula.
If there is insufficient production of surfactant, surface tension in the alveoli remains high. The alveoli cannot stay unfolded and so collapse again. This is a respiratory defect (respiratory distress syndrome, RDS) which can be fatal. The histology shows numerous collapsed or incompletely unfolded alveoli. In some cases, the bronchi and alveoli are lined with eosinophilic hyaline material (hyaline membrane disease).
Other observed anomalies are ectopic pulmonary tissues, incorrect division of the lung buds that can lead to an anomalous bronchial tree, and congenital lung cysts.