Chest roentgenographic findings that suggest mucoid impaction include predominantly upper lobe segmental bronchial obstruction with involvement of second-order bronchi. Densities may be bilateral, elliptical, rounded or oval, with smooth margins, as noted in the present case. When branching bronchi are impacted they have a “cluster of grapes” or gloved finger appearance. When adjacent bronchi are involved, they produce a V- or Y-shaped density with the apex pointing to the hilum. Air or mucous broncho-grams may be present, and lobar as well as complete lung collapse have been described. The bilateral recurrence of well-circumscribed densities on chest roentgenograms in a patient with asthma is characteristic of ABPA with proximal bronchiectasis.
While bronchography is the diagnostic study of choice to detect proximal bronchiectasis, it is not without risk, and computed tomography of the chest has been shown to be valuable in excluding bronchiectasis, as demonstrated in this case. Response to bronchodilators without the need for steroids is consistent with the absence of a hypersensitivity reaction to Aspergillus. Recurrent mucoid impaction producing bilateral chest roentgenographic densities may occur in the absence of ABPA. The appropriate clinical presentation along with serologic studies and computed tomography permit the exclusion of ABPA, thus avoiding the need for prolonged therapy with oral corticosteroids.