Bronchoceles represent impacted mucoid secretions within the bronchial tree. The cause can be divided by whether they result from obstruction or not.  Obstructive causes include tumor, stricture or foreign body. Non-obstructive causes include asthma, cystic fibrosis and ABPA.

Asthmatics are predisposed to aspergillus infection and therefore, ABPA infection in an asthmatic is a classic cause for a branching bronchocele.  Where asthma is the cause, a peripheral bronchocele is more common.