Following are true about bronchial cyst except –
Mostly mediastinal
50–70% occur in lungs
Usually multiloculated
Are infected quite often
Only 15% of bronchogenic cysts occur in lungs (pulmonary parenchyma).
Bronchogenic cysts 
Bronchogenic cyst is a congenital lung defect, which develops from abnormal lung budding of primitive foregut.
Most of the bronchogenic cyst arise in the mediastinum, where they are usually located in the mid mediastinum  near carina. 
About 15% of Bronchogenic cyst also occurs in pulmonary parenchyma.
When located in the lung they are more common in right lung and lower lobe.
They are lined by cuboidal or ciliated columnar epithelial cells and are usually filled with mucoid material. Complications of Bronchogenic cyst :-
Infection of the cyst leading to lung abscess (illediastinal bronchogenic cysts do not communicate with the bronchi but those situated within the lung may communicate with the airways leading to abscess formation).
Compression can produce either hyperinflation of the lung or atelactasis due to obstruction.
Tension pneumothorax (d/t rupture of cyst that communicates with bronchus).