Radiographic Findings

The admission AP portable chest radiograph demonstrates patchy and confluent, ill-defined densities in the right lower and left mid and lower lungs. Because these densities have ill-defined margins, are "soft" in appearance, and coalesce, the findings are consistent with airspace disease [1]. Other findings of airspace filling include visualization of bronchi surrounded by non-aerated lung, referred to as the "air bronchogram," and "acinar shadows," which appear as ill-defined densities, 4 to 10 mm in diameter. These shadows are often appreciated at the edge of confluent opacity [2].

Seven days later the chest radiograph shows almost complete opacification of the lungs, consistent with severe airspace disease. There is some sparing of the right upper lobe and left apex.

Differential diagnosis: The radiographic findings of airspace disease can be seen with filling of the airspace with liquid and/or cells, or when air is absorbed and not replaced, as in atelectasis [2]. Common causes of radiographic airspace disease are alveolar pulmonary edema of various causes and ARDS, airspace pneumonias, atelectasis, and pulmonary hemorrhage [1]. Tumors such as bronchioloalveolar cell carcinoma and lymphoma can fill the airspace resulting in radiographic airspace disease. Pulmonary alveolar proteinosis, eosinophilic pneumonia, mineral oil aspiration, cryptogenic organizing pneumonia, acute interstitial pneumonia, radiation pneumonitis, drug reactions, hypersensitivity pneumonitis, (and very uncommonly sarcoidosis, DIP, and UIP) can cause an airspace filling pattern [3,4].

References:

1. Armstrong P. Basic patterns in lung disease. In P Armstrong, A Wilson, P Dee, D Hansell (eds): Imaging of Diseases of the Chest, 2nd ed. St. Louis, Mosby-Year Book, 1996, pp 66-77.

2. Fraser R, Pare J, Fraser R, Pare P. Synopsis of Diseases of the Chest, 2nd ed. Philadelphia, W.B. Saunders Company, 1994, pp 166-169.

3. Reed JC. Chest Radiology: Plain Film Patterns and Differential Diagnoses, 4th ed. St. Louis, Mosby-Year Book, 1997, pp 228-229.

4. Webb W, Müller N, Naidich D. High-resolution CT of the Lung, 2nd ed. Philadelphia, Lippincott-Raven Publishers, 1996, pp 76-78.

Clinical summary Image 1

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