Mucoid impaction (lung)

Last revised by Henry Knipe on 22 Aug 2023

Mucoid impaction, also referred to as mucous plugging, refers to airway filling by retained secretions. When the bronchi become dilated due to mucoid impaction, the term bronchocele can be used 6.

Mucoid impaction may result from either obstructive or non-obstructive causes, although the latter does eventually obstruct the bronchi as well:

Non-obstructive causes are infectious or inflammatory in nature:

Mucoid impaction may appear as a branching tubular opacity that is distinct from the normal vascular shadows. This classic feature is the finger-in-glove sign and is also seen on CT. It can sometimes prove difficult to diagnose on plain radiography.

The appearance on CT can be variable, depending on where the mucous plugging occurs (i.e. central or peripheral airways).

Mucous plugs appear as fluid density material often located dependently within the bronchus, sometimes with internal gas.

The classic feature seen when plugged mucus extends along large branching airways is the finger-in-glove sign.

Several key additional features can also occur:

Prolonged mucous plugging can lead to bronchial dilatation and bronchiectasis.

  • endobronchial blood or blood clot appears similar to mucous plugging on CT

  • in some situations, there can be overlap between some endobronchial tumors per se (rather than with associated mucoid impaction)

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Cases and figures

  • Case 1
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  • Case 2: in left lower lobe bronchi
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  • Case 3: in right lower lobe on plain film
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  • Case 4: ABPA
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  • Case 5
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  • Case 6
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  • Case 7
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  • Case 8
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  • Case 9
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