Mucoid impaction (inspissated secretions) in segmental bronchial obstruction.

Localized persistent mucoid impaction as seen on the chest radiograph is a fairly common roentgen finding that always implies segmental bronchial obstruction. Collateral ventilation apparently permits air to enter the lung distal to the obstruction, outlining bronchi distended with trapped mucus or other secretions. This mucoid impaction sign has been seen in a variety of obstructing conditions, including primary and metastatic carcinoma of the lung, bronchial adenoma, tuberculous bronchostenosis, bronchial adenoma, tuberculous bronchostenosis, broncholithiasis, bronchial atresia, sequestration, pulmonary bronchogenic cyst, and foreign body. The roentgen appearance of the impacted mucus is variable, depending to a considerable degree on its orientation in relation to the direction of the x-ray beam. The presence of unexplained localized mucoid impaction is an indication for immediate study to demonstrate or exclude an obstructing bronchial lesion.