Mucoid impaction (lung)
Mucoid impaction, also referred to as mucus plugging / mucous plugging or bronchocele formation, refers to airway filling by mucoid secretions and can be obstructive or non-obstructive. It is a common pathological finding in chest imaging.
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:
- cystic fibrosis: due to impaired ciliary movement and thick secretions
- asthma: due to increased mucus production
- allergic bronchopulmonary aspergillosis (ABPA)
- other acquired conditions
Mucoid impaction may appear as a branching tubular opacity that is distinct from the normal vascular shadows. 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:
- distal lung collapse: from collateral air drift; this has not yet developed in infants and young children, which is why the distal lung is rather hyperlucent in this population (e.g. congenital bronchial atresia, foreign body aspiration)
- distal airway dilatation
- double artery sign 9
Treatment and prognosis
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)
- 1. Martinez S, Heyneman LE, McAdams HP et-al. Mucoid impactions: finger-in-glove sign and other CT and radiographic features. Radiographics. 2008;28 (5): 1369-82. Radiographics (full text) - doi:10.1148/rg.285075212 - Pubmed citation
- 2. Felson B. Mucoid impaction (inspissated secretions) in segmental bronchial obstruction. Radiology. 1979;133 (1): 9-16. doi:10.1148/133.1.9 - Pubmed citation
- 3. Glazer HS, Anderson DJ, Sagel SS. Bronchial impaction in lobar collapse: CT demonstration and pathologic correlation. AJR Am J Roentgenol. 1989;153 (3): 485-8. doi:10.2214/ajr.153.3.485 - Pubmed citation
- 4. Morgan AD, Bogomoletz W. Mucoid impaction of the bronchi in relation to asthma an plastic bronchitis. Thorax. 1969;23 (4): 356-69. Free text at pubmed - Pubmed citation
- 5. Hamer OW, Flint J, Ryan CF et-al. Mucoid impaction secondary to mucin-producing metastatic adenocarcinoma of the cervix. Br J Radiol. 2008;81 (968): e201-3. doi:10.1259/bjr/54252155 - Pubmed citation
- 6. Hansell DM, Bankier AA, Macmahon H et-al. Fleischner Society: glossary of terms for thoracic imaging. Radiology. 2008;246 (3): 697-722. Radiology (full text) - doi:10.1148/radiol.2462070712 - Pubmed citation
- 7. Lynch TB. PET/CT in Clinical Practice. Springer. ISBN:1846284309. Read it at Google Books - Find it at Amazon
- 8. Brant WE, Helms CA. Fundamentals of diagnostic radiology. Lippincott Williams & Wilkins. (2007) ISBN:0781765188. Read it at Google Books - Find it at Amazon
- 9. Theriault M, Eddy K, Borgaonkar J, Babar J, Manos D. Diseases Involving the Central Bronchi: Multidetector CT for Detection, Characterization, and Differential Diagnosis. Radiographics: a review publication of the Radiological Society of North America, Inc. 38 (1) 2018
- 10. Sae Rom Hong, Yeo Jin Lee, Yoo Jin Hong, Jin Hur, Young Jin Kim, Byoung Wook Choi, Hye-Jeong Lee. Differentiation Between Mucus Secretion and Endoluminal Tumors in the Airway: Analysis and Comparison of CT Findings. (2014) American Journal of Roentgenology. 202 (5): 982-8. doi:10.2214/AJR.13.11392 - Pubmed