CT evaluation of airway foreign bodies in children: emphasis on the delayed diagnosis and differentiation from airway mucus plugs.

Purpose: To review clinical and CT findings of airway foreign bodies (FBs) among children, with an emphasis on delayed diagnosis and differentiation from mucus plugs (MPs).

Methods: The CT findings and medical records of 27 patients (M:F = 17:10; mean age, 18.2 months) confirmed for FB (n = 20) and MP (n = 7) were reviewed. These findings were correlated with the bronchoscopic results and clinical outcomes.

Results: CT revealed air-trapping (70 %), atelectasis (35 %), pneumonia (25 %), and pneumomediastinum (5 %). Three patients with FB in the carina did not show air-trapping. The densities of the FBs ranged from 17 to 123 Hounsfield units (HU) (n = 17). Eight out of 20 patients (33 %) had a delayed diagnosis of FB. The CT of eight patients revealed air-trapping (n = 2), air-trapping with pneumonia or atelectasis (n = 3), and atelectasis only (n = 1). The airway MPs had a low density (0-5 HU) and were associated with atelectasis (29 %), atelectasis with pneumonia (43 %), and pneumonia (14 %).

Conclusion: Air-trapping of the ipsilateral lung may not be a reliable finding among patients with an FB located in the carina and with a small-calibered FB. The absence of air-trapping, the difference in the HU, and the shape of the endobronchial lesion are helpful findings in the differential diagnosis of an MP.