A bronchocele is a segment of bronchus that is filled with mucus and completely enclosed so the mucus cannot drain out. This segment is usually dilated. It is also called bronchial mucocele. If there is no obstruction to the flow of mucus, it is called mucoid impaction of bronchus. Bronchocele results from obstruction of bronchus. Overproduction of mucus can also contribute. Obstruction could be from scarring, tumor, congenital atresia, etc.
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Bronchocele Wikipedia(Text) CC BY-SA